INTEGRATED FLUIDIC FLOW NETWORK FOR FLUID MANAGEMENT

Abstract

An apparatus and method is presented for the management of fluid flow utilizing different adjacent wettability regions to form a fluidic network structure on a substrate. The fluidic network structure may include liquid-absorptive fluidic channels, where the fluid can flow within these channels and be removed from the substrate. Fluid can be moved by gravitational force, compression force, capillary force and surface tension force.

Description

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

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BACKGROUND

1. Technical Field

The technology of this disclosure pertains generally to fluid management, and more particularly to the management of fluid flow utilizing different adjacent wettability regions to form a fluidic network structure on a substrate.

2. Background Discussion

Perspiration is the primary means of thermoregulation for the human body during which sweat (mainly composed of water) is secreted on the skin and evaporation of the fluid removes the heat from the surface underneath. Without efficient sweat removal during intensive activity, accumulated sweat can drastically increase the humidity level surrounding the skin, resulting in a very uncomfortable feeling. Activewear which uses highly-wicking fabric has been the current standard solution for removing sweat from the body. These wicking-based fabrics utilize the capillary action of the fibers to absorb moisture. They depend on evaporation to dissipate the moisture and dry the fabric. However, serious problems exist in this wicking-evaporation moisture removal mode. For example, after being completely hydrated, the weight of the saturated fabric will increase and the wicking process will cease. This saturated fabric can result in an uncomfortable feeling on skin. The gas permeability of the fabric will also decrease as the moisture blocks the air channel between the fibers of fabric.

The current sports apparels are composed of liquid-absorptive fabric throughout the whole garment, with interconnected hydrophilic regions for absorbing perspiration. Once a portion of the garment touches perspiration, it quickly absorbs the moisture and spreads it over a large area of the garment. Due to the capillary-wicking principle, the moisture will be transported from the wet area to the dry area of the shirt until the whole garment is saturated. This mechanism works satisfactorily with small amounts of perspiration but performs poorly when the wearer perspires heavily. When the wearer rapidly perspires, the whole garment becomes equally wet, heavy, sticky and uncomfortable, even on the regions of the body where the garment barely touches the skin. The saturated fabric then blocks the vapor transport route from the skin to the environment and inhibits the evaporative cooling on the body's surface. Moreover, the regions of the body that rarely touch the fabric can experience an unpleasant chill due to the evaporation of the moisture on the saturated shirt that is in contact with the skin.

One cause for the aforementioned problems is that when designing these typical garment structures, the fact that the human body has various sweat rates on different sections of the body is overlooked. The dryness of the fabric over the area where sweat is slowly secreted or infrequently touches the garment (e.g. chest, abdomen and lower back) is sacrificed in order to absorb the sweat from heavy perspiration regions (e.g. head, neck, and upper back). For example, the front panel of a shirt is often quickly saturated by the perspiration running down from the head and neck regions, instead of the chest and abdomen regions where the fabric mainly covers. Similarly, the lower region of shirt's back panel, though infrequently in contact with the skin, is often saturated by the sweat running down from the head/neck and upper back region where sweat is generated more quickly and skin is more closely compressed with the garment. These fabrics do not manage moisture in a way that is comfortable for the human body.

Newly developed high-tech fabrics, including NanoTex® and wicking window, try to solve this problem by modifying the inner surface layer of the fabric. For example, the NanoTex® invention modifies the inner surface layer (the surface in contact with a moisture producing surface or skin) of the fabric to be less hydrophilic than the outside. As a result, the moisture will tend to be transferred to the outside surface layer of the fabric and evaporate. The wicking window fabric utilizes a similar idea. The inner surface layer of the fabric is modified to form a discontinuous hydrophobic pattern. Consequently, the wet area inner surface layer the fabric is reduced and more moisture is transferred to the outside of the fabric to be absorbed. However, critical problems still exist in these fabrics. There is reduced gas permeability and a huge increase in weight when the fabric absorbs the liquid.

Another example fabric utilizes a 3D knitting structure (X-bionic®) to create a curved structure of the fabric to reduce the contact area of the fabric and improve the gas flow. However, the total area of the fabric is increased because of the curving. The increased area results in an additional increase in the weight change when the fabric becomes wet compared with normal fabric.

Another example is Dri-release® fabric which utilizes a blend of hydrophilic and hydrophobic fibers to resolve the common problem of natural fibers. However, the final outcome is still a hydrophilic fiber that does not enable the transport or removal of fluids when made into fabrics.

BRIEF SUMMARY

An apparatus and method are described that utilize different wettability regions to form a fluidic network structure for fluid management. According to one embodiment of the described technology, the fluidic network structure includes fluidic channels that are formed by the different wettability regions within a substrate. These fluidic channel networks can be designed like a siphon system within the substrate and can utilize primarily gravitational force to transport and remove moisture, instead of by capillary absorption. In some situations, the surface tension force or compression force exerted by the fabric on the moisture will facilitate fluid transport.

In one aspect of the presently described technology, the substrate includes different wettability regions that are liquid-absorptive and form a wettability gradient. When fluid contacts the substrate, the fluid moves along the gradient from the less liquid-absorptive regions to the more liquid-absorptive regions.

In another aspect of the present technology, the substrate includes fluidic channels that are formed by adjacent liquid-absorptive and liquid-repellent regions. Fluid movement into the liquid-absorptive fluidic channels can be facilitated by compression force generated by the liquid-repellent regions.

Further aspects of the technology described herein will be brought out in the following portions of the specification, wherein the detailed description is for the purpose of fully disclosing preferred embodiments of the technology without placing limitations thereon.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

The technology described herein will be more fully understood by reference to the following drawings which are for illustrative purposes only:

FIG. 1A is a schematic front view of a liquid-absorptive region forming a channel within a liquid-repellant region of a substrate, according to an embodiment of the present description.

FIG. 1B is a schematic side sectional view of the material in FIG. 1A in contact with skin.

FIG. 2A is a front view of examples of liquid-absorptive regions forming channels in different shapes.

FIG. 2B is a front view of a liquid-absorptive region that extends the entire length of the substrate.

FIG. 2C is a front view of two fluidic channels on a substrate where the majority of the area is still liquid-absorptive.

FIG. 2D through FIG. 2F are front view diagrams of examples of fluidic channel networks.

FIG. 3A is a front view of a fluidic network configured to collect moisture from a wide area and carry it to a center dripping point.

FIG. 3B is a front view of a fluidic network configured to collect moisture from a wide area and carry it to side dripping points.

FIG. 4A and FIG. 4B are diagrams of examples of how fluidic channels may be formed into shapes, specifically into heart shapes, according to an embodiment of the present description.

FIG. 5A through FIG. 5C are diagrams of different dripping point shapes, according to embodiments of the present description.

FIG. 6A is a front view of a liquid-absorptive channel where the bottom of the channel is covered by a liquid-repellent layer.

FIG. 6B is a side sectional view of the material in FIG. 6A.

FIG. 6C is a front view of a liquid-absorptive channel where the bottom of the channel is exposed, as it would be on the outer surface layer of the substrate.

FIG. 6D is a side sectional view of the material in FIG. 6C in contact with the skin showing fluid flow paths.

FIG. 7A through FIG. 7C are diagrams that illustrate an embodiment in which the inner surface layer (layer in contact with a moisture producing surface) of the material (FIG. 7A) has more liquid-repellent region area coverage than the outer layer of the material (FIG. 7C). FIG. 7B is a cross-sectional view of the fluidic channel design of FIG. 7A.

FIG. 8A is a front view of the inner surface layer of a material with liquid-absorptive circles that penetrate through the substrate and connect to the material's outer layer fluidic channel network.

FIG. 8B is a diagram of the cross-section view of the fluidic channel design of FIG. 8A.

FIG. 8C is a front view of the outer layer's fluidic channel network of the material shown in FIG. 8A and FIG. 8B.

FIG. 9A is a front view of the inner surface layer of a material with liquid-absorptive circles that penetrate through the substrate and connect to the material's outer layer fluidic channel network. In this embodiment, the shape of the channel is abstract instead of rectangular.

FIG. 9B is a diagram of the cross-sectional view of the fluidic channel design of FIG. 9A.

FIG. 9C is a front view of the outer layer's fluidic channel network of the material shown in FIG. 9A and FIG. 9B.

FIG. 10A is a front view of the inner surface layer of a material with liquid-absorptive circles that penetrate through the substrate and connect to the material's outer layer fluidic channel network.

FIG. 10B is a cross-sectional view of the fluidic channel design of FIG. 10A.

FIG. 10C is a diagram of the outer surface layer's fluidic channel network of the material shown in FIG. 10A and FIG. 10B, where the liquid-absorptive channels on the outer surface layer of the substrate have regions that are narrower than the liquid-absorptive regions that connect to the inner surface layer.

FIG. 11A through FIG. 11C are diagrams of an embodiment of the present description in which the outer surface layer of the fluidic channel network pattern is completely covered by a liquid-repellent coating. FIG. 11A shows the inner surface layer, FIG. 11B is a cross-sectional view of the fluidic channel design of FIG. 11A and FIG. 11C shows the outer surface layer.

FIG. 12 is a front sectional view of an embodiment of a fluidic network structure configured to manage the moisture produced by the condensation process.

FIG. 13 is a perspective view of an embodiment of a liquid-absorptive fluidic channel that is sandwiched between an inner and outer liquid-repellent layer.

FIG. 14 is a front view that shows different configurations of a fluidic channel.

FIG. 15A through FIG. 15C are diagrams of one embodiment of the present description where the thickness of the material at the liquid-absorptive regions on the inner surface layer can be larger and extend outward further than the rest of the material. FIG. 15A is a front view that shows the inner surface layer, FIG. 15B shows a cross-sectional view of the material of FIG. 15A and FIG. 15C shows the outer surface layer of the material.

FIG. 16A through FIG. 16C are diagrams of an embodiment of the present description with liquid-repellent supporting structures. FIG. 16A is a front view showing the inner surface layer of the material, FIG. 16B shows a cross-sectional view of the material of FIG. 16A and FIG. 16C shows the outer surface layer of the material.

FIG. 17A is a cross-sectional view of an embodiment of the present description where the liquid-repellent supporting structures are positioned on the outside of the substrate material to enable the addition of a dry layer for separation between the liquid-absorptive channel and the additional layers of clothes people may put on the outside of the fluidic channels.

FIG. 17B is a front view of the outer surface layer of the embodiment shown in FIG. 17A.

FIG. 18A through FIG. 18D are diagrams showing how multiple layers of material can also be combined to form the fluidic network structure or provide additional functions to the basic fluidic network structure. FIG. 18A is a front view of the inner surface layer of the material (substrate with the fluidic network structure). FIG. 18B is a side cross-sectional view of the material shown in FIG. 18A. FIG. 18C is a side cross-sectional view of a slightly different alternative for the embodiment of FIG. 18A where the partially liquid-repellant region can be replaced or enhanced by a film made of completely liquid-repellant material which can be closely attached to the back of the fabric using adhesive to prevent the fluidic flow from touching the skin. FIG. 18D is a front view of the outer surface layer of the material, according to an embodiment of the present description.

FIG. 19 is a front view of an embodiment of the present description where a region of the fluidic channel network is connected to a patch of absorptive material that can collect moisture and prevent it from dripping off of the material.

FIG. 20 is a front view of an embodiment of the present description where the dripping point of a liquid-absorptive channel is a moving structure that can switch the dripping point to a moisture absorptive collection region.

FIG. 21A is a diagram of a liquid-absorptive channel configured to utilize surface tension-driven flow, with an increasing width from one end to the other, according to an embodiment of the present description.

FIG. 21B is a diagram illustrating the direction of the fluid flow for the fluidic channel embodiment shown in FIG. 21A.

FIG. 22A is a diagram of a substrate with a liquid-absorptive region surrounded by a less liquid-absorptive region to form a liquid-absorptive gradient.

FIG. 22B is a diagram illustrating the direction of the fluid flow for the fluidic channel embodiment shown in FIG. 22A.

FIG. 23A and FIG. 23B are images of a small piece of fabric with the integrated fluidic network structure. FIG. 23B shows the inner surface layer of the fabric. FIG. 23B shows the outside surface layer of the fabric with a droplet at the dripping point.

FIG. 24 is a schematic diagram of an example of how the fluidic network structure can be constructed by printing a liquid-repellent coating pattern onto a liquid-absorptive substrate using a screen roller.

FIG. 25A is a top view that shows how the material's outer surface layer channel pattern is printed using a screen roller, which penetrates the substrate completely to form the fluidic channel structure.

FIG. 25B is a side view of a close-up of the material after printing the outer layer channel pattern.

FIG. 26A is a diagram that shows how the material's inner surface layer channel pattern is printed using a screen roller which penetrates the substrate half way to form the fluidic channel structure.

FIG. 26B is a diagram of a close-up of the material after printing the inner surface layer channel pattern.

FIG. 27A is a diagram of the outer layer of a knitted fluidic channel structure according to an embodiment of the present description.

FIG. 27B is a diagram of the inner surface layer of a knitted fluidic channel structure according to an embodiment of the present description.

FIG. 27C and FIG. 27D are diagrams of close-up top views of the knitted fluidic channel structure according to an embodiment of the present description.

FIG. 28A through FIG. 28C are graphs that show how channel length, width and textile porosity, respectively, can influence the flow rate of the fluidic network system.

FIG. 29 is a graph that shows how the shape of the dripping point can influence the flow rate of a particular fluidic channel network.

FIG. 30A is a front view of the fluidic channel pattern used on the outer surface layer of the fabric sample that was compared to a fabric sample with no fluidic channel networks for fluid management.

FIG. 30B is a front view of the fluidic channel pattern used on the inner surface layer of the fabric sample that was compared to a fabric sample with no fluidic channel networks for fluid management.

FIG. 31 is an image comparing a conventional moisture-wicking polyester fabric sample and a fabric sample with fluidic channel patterns after approximately 10 seconds of water flowing down the fabric samples.

FIG. 32A is a diagram of a condensation control material with a fluidic channel network according to an embodiment of the present description.

FIG. 32B is an image of a condensation control material with a fluidic channel network collecting moisture according to an embodiment of the present description.

FIG. 33A and FIG. 33B show images of the font and back, respectively, of a shirt fabricated with fluidic channel networks that are repeated throughout the garment.

FIG. 34A and FIG. 34B depict front and back schematic views of shirts that illustrate how the fluidic channels on a shirt may be arranged so that the formation and dripping of the droplets become unobvious.

FIG. 35A is a diagram of the front side of a shirt with one liquid-absorptive region that begins at the collar and extends to the bottom of the shirt and two liquid-absorptive regions on either side of the shirt that begin at the shoulders and extend down to just below the middle of the shirt, all of which are separated by liquid-repellent regions.

FIG. 35B is a diagram of the back side of a shirt with an upper liquid-absorptive region and a middle liquid-absorptive region.

FIG. 36A is a diagram of the front side of a shirt with a middle liquid-absorptive region which extend from the collar to the bottom of the shirt and two side liquid-absorptive regions.

FIG. 36B is a diagram of the back side of a shirt with two main liquid-absorptive regions.

FIG. 37A is a diagram of the front side of a shirt with the same channel design as the shirt in FIG. 36A with the addition of fluidic channels on the sleeves of the shirt.

FIG. 37B is a diagram of the back side of a shirt with the same channel design as the shirt in FIG. 36A with the addition of fluidic channels on the sleeves of the shirt.

FIG. 37C is a diagram of the side view of a shirt with the same channel design as the shirt in FIG. 36A with the addition of fluidic channels on the sleeves of the shirt.

FIG. 38A and FIG. 38B are diagrams of the front and back, respectively, of a shirt with a bottom liquid-absorptive panel and two side liquid-absorptive panels.

FIG. 38C is an image of the shirt described in FIG. 38A with the liquid-absorptive panel on the bottom shown collecting the sweat from the wearer after exercise.

FIG. 38D is an image of the shirt described in FIG. 38A and FIG. 38B where the side panels are shown collecting the sweat from the wearer after exercise.

FIG. 39A and FIG. 39B show a diagram of the front and back, respectively, of a shirt with a liquid-absorptive region which covers both the collar and chest area and extends to the side dripping points of the shirt while the abdomen region is kept liquid-repellent.

FIG. 40 is a diagram of an example fluidic channel network in the shape of a tree patterned on the front outer surface layer of a shirt.

FIG. 41A is a diagram of the front side of a shirt that has three regions of liquid-absorptive channels separated by liquid-repellent regions.

FIG. 41B is a diagram of the back side of a shirt that has four regions of liquid-absorptive channels separated by liquid-repellent regions.

FIG. 42A is a diagram of an example fluidic network structure as applied to the waistband of a pair of shorts.

FIG. 42B is an image of an example fluidic network structure as applied to the waistband of the front of a pair of shorts.

FIG. 42C is an image of an example fluidic network structure as applied to the waistband of the side of a pair of shorts.

FIG. 43 is a diagram of an example fluidic network structure as applied to the waistband and upper area of a pair of shorts.

FIG. 44 is a diagram illustrating another fluidic channel network configuration where fluid-absorptive channels cover the shorts to transport the sweat to the sides of the shorts and drip it away via the dripping points.

FIG. 45 is a diagram of one embodiment of a sock with a fluidic network structure that has fluidic channels that carry the sweat running down the leg to the sides of the sock and drip it away via dripping points.

FIG. 46A shows a front view of one embodiment of a headband with a fluidic network structure.

FIG. 46B through FIG. 46D are images of the embodiment shown in FIG. 46A.

FIG. 47 is a diagram of one embodiment of a cycling garment with a fluidic network structure.

FIG. 48A is a perspective view of one embodiment of a four cornered tent with a fluidic network structure.

FIG. 48B is a perspective view of one embodiment of a cylindrical tent with a fluidic network structure.

DETAILED DESCRIPTION

Wettability is a characterization of the interaction between the surface of a material and a liquid. Based on the wettability differences within a single material, when liquid contacts the material's surface, it will either be absorbed or repelled by the material's surface. This can be summarized as two states of wettability: liquid-absorptive and liquid-repellent. The liquid wettability of a material's surface is related to the contact angle of the material's fiber for a certain liquid, α, geometry of the porous structure, characterized by the average pore radius, r (note that for a fabric structure, the pore radius can be estimated as the distance between two adjacent fiber peaks) and the property (surface tension, γ and liquid pressure, P_L) of the liquid on it. Either absorption or repellency of the liquid can be roughly determined by a critical value, S, which is called the value of wettability:

$\begin{array}{cc}S=P_L+\frac{2\gamma \cos \alpha }{R}& \left(\mathrm{Eq}.1\right)\end{array}$

If S>0, the liquid will be absorbed by the fabric. If S<0, the liquid will be repelled by the fabric. The larger the number, the more liquid-absorptive the material. Equation 1 provides a way to generally and quantitatively compare the wettability of two surfaces. From the above relationship, it is shown that the wettability is indeed a combination of these parameters and is different depending upon a given condition.

It should be noted that the definition of wettability is much broader and more accurate than the conventional definitions of a “hydrophilic” and “hydrophobic” material. Usually, a material with a contact angle of water smaller than 90° is called hydrophilic and above 90° is called hydrophobic. This phenomenon can be understood from the equation above: when a is smaller than 90°, cos α is larger than zero and S is usually larger than zero (unless the liquid pressure P_L is much lower than zero), which means a liquid will be absorbed into the material. However, even when the contact angle is above 90° (hydrophobic) and the right hand side of the equation is negative, a small amount of pressurized water or a micro tiny water droplet with a large P_L is still likely to be absorbed by the material.

For example, the failure of water repellency has been observed when a high-speed pressurized water stream is used to impact a liquid-repellent surface, where the material holds the water and becomes “liquid-absorptive.” Therefore, “liquid-repellent” and “liquid-absorptive” will be consistently used herein to describe the overall wettability of the material structure.

It should be noted that the wettability of the material should not be viewed as a fixed structure or contact angle of the material, but as a specific character of the material's structure under a given range of liquid properties and conditions. For example, a liquid-repellent region for sweat control might become a liquid-absorptive region for condensation collection since the liquid pressure is larger in the latter condition.

Referring more specifically to the drawings, for illustrative purposes, embodiments of the apparatus and method for managing fluid flow using materials with liquid-absorptive and liquid-repellent (or less liquid-absorptive) regions that form a fluidic network structure are described herein and depicted generally in FIG. 1A through FIG. 48B. It will be appreciated that a structure depicted in multiple figures throughout the description is given the same reference number. It will also be appreciated that the methods may vary as to the specific steps and sequence without departing from the basic concepts as disclosed herein. The method steps are merely exemplary of the order that these steps may occur. The steps may occur in any order that is desired, such that it still performs the goals of the claimed technology.

FIG. 1A is a schematic diagram of one embodiment 100 of a liquid-absorptive region 102 forming a channel 118 within a liquid-repellent region 104 of a substrate 106. The wetting contrast between these two regions will form a virtual channel 118 to confine the liquid flow inside the liquid-absorptive region 102, while the liquid-repellent region 104 remains dry. Many fluidic channels 118 can be formed on a particular substrate 106 to form fluidic network structure designs (siphon networks). For the most efficient fluid removal, the orientation of the liquid-absorptive channels 118 within the fluidic network design should not be completely horizontal when being used. The bottom lowest gravitational region of the channel 118 is called a dripping point 108. The dripping point 108 is generally where the liquid-absorptive region 102 and adjacent liquid-repellent region 104 meet at the lowest gravitational point of a channel 118. The fluid flowing down along the length, L, of the channel 118 will accumulate at the dripping point 108 until the fluid forms a droplet 116 that grows big enough to fall away from the material. The width, W, of the channel may vary according a particular application.

As shown in FIG. 1B, when the material (the substrate with a fluidic network structure) is in contact with human skin 110 for example, the moisture 112 on the skin 110 in contact with the liquid-absorptive region 102 of the material will be quickly absorbed and will wet the channel region. Moisture 112 in contact with the channel 118 will be continuously sucked into the channel 118 due to a siphon-like principle where the gravitational force keeps the moisture moving downward 114. This results in a majority of the channel 118 remaining unsaturated. The moisture 112 will be drawn into the unsaturated part of the channel 118 due to the pressure difference.

As a result of this self-sustaining process, the excessive moisture 112 that has not evaporated will gradually accumulate at the bottom dripping point 108 of the channel 118. Droplets 116 can form at the dripping point 108 and will be initially pinned at the dripping point region due to the hysteresis which results from the large contact angle difference between liquid-absorptive and liquid-repellent regions. The droplets 116 will keep growing bigger as more moisture is collected. Droplets will detach and drip off from the surface of the material as gravitational force becomes larger than the hysteresis force.

The flow along the channel 118 direction comprises two parts: one is the free surface flow on the surface of the material and the other is the flow inside of the channel pattern. The flow rate on the outer surface layer, Q_s, and the inner surface layer (the layer in contact with a moisture producing surface) flow rate, Q_i, of the liquid-absorptive pattern can be characterized by equations 2, 3 and 4 below:

$\begin{array}{cc}{Q}_i~\frac{\mathrm{kWT}}{\mu L}\Delta P& \left(\mathrm{Eq}.2\right)\\ Q_s~\frac{H^3}{\mu }\frac{\Delta P}{L}& \left(\mathrm{Eq}.3\right)\\ \frac{\Delta P}{L}~\rho g\cos \theta & \left(\mathrm{Eq}.4\right)\end{array}$

where k is the permeability of the fabric to fluid, L, W and T are the length, width and thickness, respectively, of the liquid-absorptive region, ΔP is the hydrostatic pressure, H is the thickness of the surface fluid film, μ is the viscosity of the fluid and θ is the angle between the channel's orientation and the vertical (gravitational) direction (the range is 0 to 90 degrees which is completely horizontal). This angle can vary with different orientations of the material during motion and should always be calculated with reference to the present direction of gravitational force.

The moisture that is not directly underneath the liquid-absorptive pattern can be partly pushed towards the fluidic channel by squeezing from the liquid-repellent region 104. This “pushing” transport is significant if the material is in close and compressed contact with a moisture producing surface, such as human skin for example. This can be seen when the fluidic network structure is applied to apparel and is stretched against skin during motion or worn as a compression garment. During this process, the majority of the moisture 112 is removed by the fluidic network (see FIG. 2D through FIG. 2F) and dripping of the excess moisture, while the liquid-repellent area remains dry and forms a barrier to block the fluid from flowing underneath.

The moisture-removal enabled by the fluidic network structure on apparel can maintain the necessary amount of moisture 112 on the skin 110 for cooling by evaporation and allows the vapor to freely pass through the dry area (liquid-repellant region 104) of the material 106. The fluidic channel structure itself keeps removing the excessive moisture only. This structure provides a combined cooling effect of the wet fabric pattern itself and the evaporation cooling on skin.

Although sweat on skin is used as an example to explain the moisture transport process of many embodiments of the material, it should be noted that the structure can be applied to a broad range of moisture management applications. This includes removal of moisture on different surfaces, removal of condensation, spill control, fuel cell electrodes, etc. The moisture can be water, bio-fluid (sweat, urine, blood, etc.), oil, organic solvents and many others. In addition, the terms “hydrophilic” and “hydrophobic,” are general descriptions of a material's affinity for liquid. Use of these terms does not limit the structure to water-related applications. One can derive the appropriate structure and material for each situation based on the theory of liquid wettability on fabric aforementioned.

Referring now to FIG. 2A, the shape of the liquid-absorptive region 102 (or channel) can be rectangular, triangular, circular, polygon, etc. and is not limited. The shape can be tilted and have various angles, θ. The liquid-absorptive region 102 can also extend through the entire length of the material, as shown in FIG. 2B. Multiple channels 118 can be in contact to form a fluidic channel network to transport the moisture over an area to the dripping point 108. Three examples of fluidic channel networks are shown in FIG. 2D, FIG. 2E and FIG. 2F. The location of the channels 118 on the substrate can be arbitrary. The channel patterns can also be repeated to cover the whole substrate.

The width of the liquid-absorptive channel pattern can vary depending on the application of the fluid management system. The length of the liquid-absorptive region 102 or network pattern can be very short or as long as the length of the material (see FIG. 2B). The ratio of the liquid-absorptive area to the liquid-repellent area is not limited. FIG. 2C illustrates two fluidic channels 118 on a material where the majority of the area is still liquid-absorptive 102.

In one embodiment, shown in FIG. 3A, a fluidic network of channels 118 may be constructed to collect a wide area of moisture 112 to a center dripping point 108. Alternatively, the channels 118 can be constructed so that all of the excess moisture can be divided to the two side dripping points 108 and drip away, as shown in FIG. 3B.

In another embodiment shown in FIG. 4A, the fluidic channels 118 can be constructed to be curved lines that form an esthetic pattern, such as a heart shape. Alternatively, different lengths of channels 118 can be positioned into a patterned shape, as shown in FIG. 4B.

In yet another embodiment, the liquid-absorptive channel pattern can be colored with a different dye on a fabric so that it stands out as a decoration on a garment whether the pattern is wet or dry.

The shape of the dripping point 108 can affect the dripping rate of the fluidic channel network. The dripping point 108 can have a different geometry than the channel, which can accelerate or slow the dripping process of the fluidic channel network and can also affect the overall fluid removal rate of the fluidic channel network siphoning system. For example, a narrow dripping point (in relation to the channel width) will accelerate the droplet dripping rate of the channel. FIG. 5A through FIG. 5C show examples of different dripping point 108 shapes. The dripping point shown in FIG. 5A creates a higher droplet dripping rate than those shown in FIG. 5B or FIG. 5C.

Though the channel 118 should be liquid-absorptive, the thickness of that liquid-absorptive region 102 can be non-uniform throughout the substrate. In other words, part of the liquid-absorptive region 102 can be modified to be less liquid-absorptive or liquid-repellent to further reduce wetness of the fabric and promote fluid management.

In one embodiment 600 shown in FIG. 6A through FIG. 6D, the bottom region 602 of the liquid-absorptive region 102 can be covered by a liquid-repellent layer 604. FIG. 6A shows the inner surface layer of the material that would be in contact with the fluid producing surface, in this example, human skin. FIG. 6B shows a cross-section view of the material and illustrates how the bottom region 602 of the liquid-absorptive region 102 (channel) can be covered by a liquid-repellent layer 604. FIG. 6C shows the outer surface of the material. FIG. 6D shows how this design can facilitate the accumulated droplet 116 drip at the bottom of the fluidic channel on the outer layer of the material instead of flowing backward to the gap between the skin and the inner layer of the material. In this embodiment, the length of the liquid-repellant pattern is long enough so that the hydrostatic pressure of the liquid inner layer of the material is higher than the Laplace pressure of the outside dripping droplet ΔP₂.

FIG. 7A through FIG. 7C are diagrams that illustrate an embodiment 700 in which the inner surface layer of the material 106, shown in FIG. 7A, has more liquid-repellent region 104 area coverage than the outer surface layer of the material, shown in FIG. 7C. The inner surface layer (in contact with the liquid-producing surface) of the material has a discontinuous liquid-absorptive region 102 in a pattern 702 made up of small circles (or any other shape). These liquid-absorptive regions 102 on the inner surface of the material are connected through liquid-absorptive paths 704 to the outer layer liquid-absorptive channels 118 of the material, as shown in the cross-section view in FIG. 7B. The liquid-absorptive regions 102 forming the pattern 702 on the inner surface layer of the material serve as small inlets that suck moisture to the outer siphon networks (liquid-absorptive channels 118). The moisture removal rate of this structure from an inner surface layer to an outer layer is strongly limited by the size of the inlet, which serves as a channel connecting the inner and the outer surface layers of the material 106. The larger the size of the inlet, the quicker the flow rate.

The inner surface layer pattern of the material can be as simple as circles or the pattern can be complex. The size of the pattern can be varied. The inner surface layer liquid-absorptive pattern can be larger or smaller than the outer layer pattern size.

In the embodiment 800 shown in FIG. 8A through FIG. 8C, the inner layer of the material, shown in FIG. 8A, has 5 mm liquid-absorptive circles 802 with a 5 mm space between each circle 802. The uniformly distributed liquid-absorptive pattern ensures an efficient capture of moisture. The liquid-absorptive circles penetrate through the material substrate and connect to the outer layer of the material which has a fluidic channel network design that connects the entire liquid-absorptive circle pattern on the inner layer of the material. The channel design uses a minimum number of channels 118 to connect all of the liquid-absorptive circles so that the overall wet area on the material is minimized. The outside layer channel patterns are also designed so that they can be repeated over the entire material substrate. FIG. 8B shows a cross-sectional view of the design. FIG. 8C shows the outer surface of the material. The outer layer channels 118 are mainly vertical (5.5 mm in width and 5 mm apart) with two 45 degree tilted channels that connect the lines and merge them into one dripping point 108 at the bottom of the main channel.

The embodiment 900 in FIG. 9A through FIG. 9C is a variation of the embodiment shown in FIG. 8A through FIG. 8C. In this embodiment 900, the liquid-absorptive channels 118 are an irregular shape instead of rectangular and the liquid-absorptive paths are smaller at the inner surface layer (FIG. 9A) and get larger as they go through the thickness of the material to the outer layer to the fluidic channels 118.

In the embodiment 1000 shown in FIG. 10A through FIG. 10C, the liquid-absorptive channels 118 on the outer layer of the material 106 (FIG. 10C) have narrow regions 1004 that are narrower than the liquid-absorptive regions that connect to the inner surface layer 1002. This design can further reduce the wet area of the entire material while maintaining a similar transport rate through the liquid-absorptive regions that connect to the inner surface layer 1002. FIG. 10A shows the liquid-absorptive regions that connect to the outer layer 1002 patterned on the inner surface of the material 106. FIG. 10B shows a cross-section view of the embodiment 1000.

Alternatively, a large portion of the fluidic channel on the inner surface layer of the material can be covered by a liquid-repellent coating. This region of the channel can serve as a rapid transport channel for the moisture and can prevent any possible liquid leaking back to the inner surface layer of the material. This design can also prevent the adhesion of the hydrophilic channel area to the skin and prevent the disruption of fluid flow due to the capillary pressure. In addition, the design can also help reduce the unpleasant feeling when a large amount of fluid is flowing on perspiring skin, such as when the material is used as an exercise garment for example. The fluidic channel provides freedom for the design as well as more control of the direction of the fluid movement.

Similarly, the diagrams in FIG. 11A through FIG. 11C show an embodiment 1100 in which the outer surface layer (FIG. 11C) of the fluidic channel network pattern is completely covered by a liquid-repellent coating, as shown in the cross-sectional view in FIG. 11B. The inner surface layer of the pattern can remain constant from the top of the material to the dripping point 108 as shown here or can resemble any of the embodiments previously shown or any other patterns suited for a particular need. This provides a region where moisture can contact the channel 118 and flow inside the material but is not visible from the outside of the material, as shown in FIG. 11C. This embodiment can be particularly useful when made into a compression garment, which will generate contact pressure that pushes the moisture towards the liquid-absorptive region 102 patterns. The accumulated moisture can be kept or transported away by the liquid-absorptive channel 118 structure. Furthermore, this embodiment solves the problem of having to wear a completely uncomfortable, liquid-repellent fabric when sweating. It provides a fabric design that removes sweat and cools the body, while maintaining its liquid repellency and dustproof characteristic on the outside of its surface.

This embodiment can also be useful in reducing and managing condensation on the surface of the material. The design 1200 shown in FIG. 12 demonstrates one possible embodiment of a fluidic network structure for controlling the moisture 1202 produced by the condensation process. The pattern controls the larger sized droplets that are able to stay on the material because of the gap, D, between the liquid-absorptive channels. Any droplet that grows to a size larger than D will be transported away by the liquid-absorptive fluidic channel and finally collected at the bottom dripping point 108.

In an alternative embodiment 1300 shown in FIG. 13, a completely sealed or closed liquid-absorptive channel 118 can be formed within a material using a sandwich structure where two liquid-repellent regions 104 are on the inside and outside of the material and there is a liquid-absorptive region 102 in the middle of the material. This type of structure may be helpful in ensuring a particular direction of fluid flow within the fabric. Moreover, this design can be used to eliminate the flow channel 118 appearance on the outside of the material, fabric, garment, etc. Generally, when colored fabrics become wet, they look darker. In this embodiment 1300, the channels 118 of the siphon network will become more or less invisible. This closed channel structure helps eliminate possible visualization of the channel structure. This structure can be part of a full channel pattern. The water picked up by side channels (not shown) can be fed into this channel and drip away at the bottom of this structure.

The channel structure can also be separated by a middle layer liquid-repellent barrier that separates the fluid flow. In other words, a fluidic “diode” structure can be incorporated into the fluidic networks to eliminate any reverse wicking flow between adjacent dry and wet collection channels. In the variations shown in FIG. 14, three vertical channels 118 are all separated from the main transporting channel 118′ by a liquid-repellant gap 1402 of distance d. When the moisture is moving down from one of the vertical channels 118, it will be accumulated at the boundary where the liquid-absorbent and liquid-repellant regions meet. Once the liquid collects enough to overcome the liquid-repellant gap 1402, it will flow down to the transporting channel 118′ and be transported away. On the contrary, when the transporting channel 118′ is wet, the moisture will not move into the dry vertical channels 118 due to the liquid-repellant gap 1402. This structure may be used to separate liquid-absorptive regions within one network or between networks. The shape of the gap can be triangular, rectangular, or any other shape to fit a particular purpose. The position can be within the transporting channel, above the transporting channel or at the edge of the transporting channel and is not limited.

In one embodiment 1500, the thickness of the material at the liquid-absorptive regions on the inner surface 1502 can be larger and protrude outward further than the rest of the substrate material 106, as shown in FIG. 15A through FIG. 15C. This additional thickness or supporting structure can promote the stability of the liquid-repellent region 104 and improve its robustness against friction and compression during motion. FIG. 15A shows the inner surface layer, FIG. 15B shows a cross-section view and FIG. 15C shows the outer surface layer of the material.

Alternatively, there can be supporting structures 104′ of the liquid-repellant region 104 on the inner surface layer of the material 106, as shown in the embodiment 1600 in FIG. 16A through FIG. 16C. FIG. 16A shows the inner surface layer of the material, FIG. 16B shows a cross-section view of the material and FIG. 16C shows the outer surface layer of the material. This additional thickness of the liquid-repellent region can enhance the robustness of the dry regions on the inside of the fabric. It also helps reduce the areas of the wet regions that are in direct contact with the skin on the inside of the fabric.

Referring now to FIG. 17A and FIG. 17B, the supporting structures 104′ can also be positioned on the outer surface layer of the substrate 106 to enable the addition of a dry layer 1702 for separation between the liquid-absorptive channel 118 and the additional layers of clothes people may put on the outside of the fluidic channels, for example. This embodiment 1700 can be varied slightly so that the bottom portion of material is patterned with liquid-absorptive channels 118 and adhered to another layer of strong liquid-repellent material (a water repellant dry layer 1702) to provide both outside water repellency (required for a garment such as outdoor rain gear) and inner layer quick moisture removal capacity that is not limited by humidity or temperature. This structure achieves a “one-directional” moisture transport scheme. Alternatively, there can be supporting structures 104′ on both the inner and outer surface layers of the material (not shown).

It should be appreciated that the density and/or porosity of the material can be different at different regions of the material for any of the embodiments described herein.

Multiple layers of material can also be combined to form the fluidic network structure or provide additional functions to the basic fluidic network structure. In the embodiment 1800 shown in FIG. 18A through FIG. 18C, two layers of material substrate are combine. A first layer of liquid-repellant material 1802 with circle patterns 1804 can be bonded using adhesive 1806 or other bonding methods to a second layer of liquid-repellant material 1808 with the outer liquid-absorptive channel 118 patterns to form the fluidic network structure. FIG. 18A shows the inner surface layer of the material with the liquid-absorptive circle patterns 1804. FIG. 18B shows a cross-section view. In a slightly different design, shown in the cross-section view in FIG. 18C, the partially liquid-repellant region can be replaced or enhanced by a film made of completely liquid-repellant material 1810, such as fabric, rubber, plastic, polymer, metal, etc. The material can be closely attached to the back of the fabric using adhesive 1806 and prevents the fluidic flow from touching the skin. The thickness of this material is not limited. This film 1810 can be useful in resisting high fluidic pressure and can provide a barrier between the moisture flow and the skin, in cases where the material will be worn as a garment. FIG. 18D shows the outer surface layer with the fluidic channels.

FIG. 19 shows an embodiment 1900 where a region of the fluidic channel network is connected to a region of absorptive material 1902 that can collect moisture (e.g. wicking fibers, cotton, superabsorbent polymers, etc.) and prevent it from dripping off of the material. These absorptive materials will facilitate transport along the system of liquid-absorptive channels 118 on the material and lock the moisture inside so that it will not drip off of the material. This embodiment is useful in situations where people do not want the moisture to fall onto the ground (e.g. when playing indoor basketball, badminton, etc.) or when a high flow-rate transport is required.

The dripping point 108 of a liquid-absorptive channel 118 can also be a moving structure as shown in the embodiment 2000 in FIG. 20. This structure can serve as a “switch” where the dripping point of a liquid-absorptive channel can switch the dripping point to a moisture absorptive collection region. By fixing this structure to the panel of an absorptive region 2002 on the material, all of the transported moisture can be collected. By fixing this point away from the panel of absorptive material 2002, the moisture can be dripped away. In one embodiment, this structure can be an additional liquid-absorptive strip affixed to the fluidic channel and can have a reversible fixture at the tip, such as Velcro, for easy removal and attachment.

The shape of the liquid-absorptive channel 118 can be specifically designed to utilize surface tension-driven flow. The liquid-absorptive channel 118 may have an increasing width from one end to the other end and can have a triangular shape, for example, as shown in FIG. 21A. The channel can be any shape that is necessary for a given purpose, however. Referring to FIG. 21B, when a liquid droplet 116 contacts this region, it will move spontaneously toward the larger width end due to the unbalanced surface tension force at the front and back of the droplet 116.

FIG. 22A and FIG. 22B illustrate an alternative embodiment 2200 where the material comprises liquid-absorptive regions 2202 that are surrounded by less liquid-absorptive regions 2204 to form a liquid-absorptive gradient as opposed to a clear liquid-absorptive liquid-repellant interface. When water contacts the material, water will move in the direction 2206 from the less liquid-absorptive region to the more liquid-absorptive region due to the wettability gradient as shown is FIG. 22B. This structure does not require liquid-repellent liquid-absorptive contrast but a liquid-absorptive gradient. In other words, the fluid will tend to fill the regions that are more liquid-absorptive. This produces a unidirectional wicking of fluid in the substrate plane along the more liquid-absorptive region. As a result, the moisture will be non-uniformly distributed on the surface of the fabric, creating a relatively dry region on the less liquid-absorptive areas. This liquid-absorptive region can also be constructed to follow the gravity direction so that the gravity force will help the moisture to first wick through the more liquid-absorptive patterns on the material.

FIG. 23A and FIG. 23B are images of a small piece of fabric with the integrated fluidic network structure shown schematically in FIG. 8A through FIG. 8C. FIG. 23B shows the inner layer of the fabric. FIG. 23B shows the outer layer of the fabric with a droplet 116 at the dripping point 108.

The invention may be better understood with reference to the accompanying examples of how to create the fluidic network structure, which are intended for purposes of illustration only and should not be construed as in any sense limiting the scope of the presently described technology as defined in the claims appended hereto.

The fluidic network structure can be constructed by printing a liquid-repellent coating 2400 pattern 2402 onto a liquid-absorptive material 2404 using a screen roller 2406, as shown in FIG. 24. There are currently several different methods of textile printing available, including flatbed printing, rotary printing, inkjet printing, etc. Any liquid-absorptive material, including but not limited to cotton, treated polyester, nylon, silk, bamboo fibers in woven, knitted or non-woven structure, may be used as the material substrate 106. Any of the durable liquid-repellent agents, such as fluorochemicals, silicones, waxes or other similar materials, may be used to create a liquid-absorptive channel or fluidic network structure.

Some printing methods use various thickeners to keep the ink from migrating and to maintain a clear or well-defined print. In printing in general, there are a number of variables which can be controlled. Some variables such as print paste viscosity, amount of print paste applied, roller/wiper pressure, speeds, mesh size of the screen, etc., can be used to control the depth of penetration of the print paste. One way to control depth of ink penetration is to adjust the printing parameters so that the print paste can completely penetrate through the fabric without merging together. A fluidic network structure can be formed on the material substrate as defined by a print screen.

A two-step printing process can be utilized to easily create a material with internal liquid-absorptive patterns. FIG. 25A shows how the material's outer layer channel pattern is printed using a screen roller 2500 which penetrates the material substrate 106 completely to form the fluidic channel 118 structure. A close-up view is shown in FIG. 25B. For the material's inner surface layer, a screen roller with the inner surface layer pattern 2600 can be used to print again on the same side of the material substrate 106, as shown in FIG. 26A and close-up in FIG. 26B. By adjusting the printing parameters, the inner layer pattern can be only half-penetrated through the substrate so that the other side of the substrate still maintains the channel pattern. This penetration needs to be well-controlled so that the wicking behavior of the outside channel is not affected or does not become less liquid-absorptive. Two screens can be aligned in the printing process so that the inner surface layer inlet pattern lies right on top of the channel pattern. Such alignment is similar to the multi-color printing process. Similar to printing multiple colors with precise registration, the liquid-repellent patterns can be aligned very accurately.

Alternatively, the fluidic channel structure can be created by printing on one side of the material substrate, controlling the penetration thickness to more than half of the material substrate, and then printing again on the other side of the material substrate with more than half penetration. In this way, a similar fluidic channel structure can be created but the method requires rotation of the fabric during printing. For a more dense and random pattern for the inner layer design, the two screens need not be aligned during the subsequent printing process. There will always be part of the liquid-repellent pattern that lies on top of the channel pattern.

The printing process can also be used to construct the embodiment 2200 illustrated in FIG. 22A and FIG. 22B. The structure can be created by making certain regions of the material less liquid-absorptive but not completely liquid-repellent.

In another embodiment, a fluidic channel pattern can be formed on fabric with an inkjet printer. The advantage of inkjet printing is the ability to control the amounts of ink as well as the penetration power digitally, which is more accurate than other printing methods. The inkjet printer is also more flexible with regard to the printing substrate. This process works on raw fabric as well as completed shirts. Similar to the screen printing method, the fabric can be printed in two ways. In one embodiment, the fabric is printed on the front side first and then on the back side of the fabric. Alignment of the front and back pattern is not necessary if the backside patterns are dense enough to overlap the front pattern. The amount of ink injected through inkjet printing is controlled by the printing resolution, inject pressure from the head, and the distance between the inkjet head and the substrate. If too much ink is injected onto the fabric, the ink will merge together and will not achieve a good image. However, if insufficient ink is injected onto the fabric, the water repellency of the liquid-repellent region will decrease due to the incomplete coverage of the ink. Therefore, it is important to control the amount of ink used for each print.

Maintaining good resolution as well as good repellency can be achieved using a repeated printing method. Since the liquid-repellent coating is not strong without heat treatment, a certain amount of ink can be used to print the pattern, followed by a second print once the previous printing has almost dried. If necessary, repeated printing can be used. Since inkjet printing allows control of many parameters, the accuracy of this printing method can be very good.

Another method for improving the pattern resolution while maintaining a good soaking of the fibers is to use a “stroke+fill” mode. At first, a pattern is printed with only the boundaries of the pattern, and then the fabric is baked to cure the printed boundaries. After the boundaries are completely cured, another pattern that fills the empty space inside the boundary of the pattern is printed so that the pattern is completely filled. Since the hydrophobic coating defines and limits the spreading of the ink, more ink can be used on the fabric without worrying about the merging issue.

Yet another method for improving the printing process is by combining the inkjet printing with a screen printing method. The screen printing technique can apply a very large compression pressure when printing and the inkjet printing technique can provide a much better control on the printing penetration. The fabric can first be printed to form a half way penetrated pattern and then the fabric can go through a screen printing process to form the through pattern.

Another method for constructing the fluidic network structure is by stitching separate fabric pieces together into a whole garment. Specific shapes of the liquid-absorptive regions and liquid-repellent regions are predefined and cut from liquid-absorptive and liquid-repellent fabrics, followed by stitching them together at the boundaries with hydrophilic or hydrophobic threads to form a garment.

Another method is to combine knitting with a printing process. The knitting process is utilized to create the half-penetrated liquid-repellent structures and liquid-absorptive structures and the printing is utilized to create the through penetrated liquid-repellent structures.

The fabric may also be created by knitting liquid-repellant and liquid-absorptive fibers together. One embodiment of the knitted fluidic channel structure 2700 is shown in FIG. 27A through FIG. 27D. The liquid-repellant fibers 2702 can be inherently liquid-repellant or achieved by modification of liquid-absorptive fibers 2704. The liquid-repellant fibers 2702 can be arranged to form the liquid-repellent region on the fabric and knitted with the liquid-absorptive fibers 2704 to form the liquid-absorptive region and channels.

FIG. 27A shows the outer layer of the knitted material and the inner surface layer is shown in FIG. 27B. FIG. 27C shows the detailed arrangement of the knitted rib structure on the front and back side of the fabric composed of liquid-repellant fiber 2702 and liquid-absorptive fiber 2704. FIG. 27D shows how the liquid-repellant fibers 2702 and the liquid-absorptive fibers 2704 may be knitted together.

The material can be created by knitting liquid-repellent fibers to form different pore sizes at the liquid-repellent and liquid-absorptive regions. The pore size at the liquid-repellent region will be smaller than at the liquid-absorptive region, which indicates a wettability difference according to Eq. 1. As a result, under high-pressures, liquid will be pushed to the liquid-absorptive regions with larger pores and will become wet and absorptive, while the liquid-repellent region stays dry.

Knitting can also be used to construct the embodiment 2200 described in FIG. 22A and FIG. 22B. The material can be constructed utilizing liquid-absorptive fibers such as natural cotton fibers and less liquid-absorptive fibers such as pure synthetic fibers such as polyester or nylon. The structure can be achieved using a simple knitting process with controlled positioning of the two types of yarns into the designed pattern. Alternatively, the fluidic structure can be created by knitting liquid-absorptive fibers to form different pore sizes at the liquid-absorptive and less liquid-absorptive regions. The pore size of the less liquid-absorptive regions will be larger than the liquid-absorptive region.

A bonding process may also be utilized to form the fluidic network structure. A liquid-absorptive material can be cut into the shape of the channel pattern and adhered to a liquid-repellant material substrate 106 containing holes that allow the moisture to contact the liquid-absorptive channel pattern. Bonding can be achieved through techniques including thermoplastic powders, fibers or films.

A stitching process may be utilized to form the fluidic network structure on a liquid-repellant material substrate. Liquid-absorptive threads can be stitched or embroidered on a liquid-repellant material substrate to form the fluidic channels. Alternatively, liquid-repellant threads can be tightly stitched on a liquid-absorptive material substrate to define the fluidic channels.

Examples and Results

The examples disclosed herein are for illustrative purposes and are not intended to be limiting in any way.

A fabric with an integrated fluidic channel network for force-driven flow through porous material is described. The driving force of fluid management comes from the hydrostatic pressure of a liquid droplet placed in a higher position. FIG. 28A through FIG. 28C are graphs that show how channel length, width and textile porosity (“white” fabric has the largest pore size while “grey” fabric has the smallest pore size) can influence the flow rate of the fluidic system. Similarly, FIG. 29 is a graph that shows how the shape of the dripping point can influence the flow rate of a particular fluidic channel network.

Three different types of knitted fabric materials were compared to demonstrate the different influences on the stability of hydrostatic pressure of the liquid-repellent regions. Two samples of each type of fabric (A,B,C) were cut and treated with a liquid-repellent coating using an inkjet printer (Freejet 500, Omniprint) loaded with commercial fluoropolymer coating (Aqua Armor, Trek 7). Two different print settings were used to achieve approximately 50% and 100% penetration of the coating solution in the fabric. The hydrostatic pressure of each sample was measured by a lab-built setup. As shown in Table 1, for the same type of fabric A and B (single-knit jersey), the larger the pore size, the lower the hydrostatic pressure it can withstand before leaking. This implies that the fabric with larger pores is more likely to become wet when in contact with moisture, which is predicted by the wettability model. The hydrostatic pressures of half-penetrated samples also follow the trend of the fully-penetrated printing samples but possess a lower value. The interlock structure of fabric C had a similar pore size as fabric A and achieved a higher hydrostatic pressure for both print coating penetrations. This may be attributed to the less-stretchy and more stable construction of fabric C using a 100% polyester interlock structure. This characterization process was shown to be useful when selecting the appropriate substrate structure for constructing the liquid-repellent region in various applications (e.g. sweat removal, condensation, etc.).

Two fabric samples with the same structure (interlock structure, liquid-absorptive polyester, 175 gm⁻²) were prepared for comparison of fluid management utilizing fluidic channels versus moisture wicking finishes. One of the fabric samples was patterned with a fluidic network channel design as shown in FIG. 30A and FIG. 30B. The inner layer pattern, shown in FIG. 30B, penetrated about half of the fabric's thickness.

In one demonstration, a 6 cm×9 cm piece of the fluidic network fabric 3102 and a 6 cm×9 cm piece of the conventional moisture-wicking polyester 3104 were both fixed on plastic boards as shown in the image 3100 in FIG. 31. A syringe pump 3110 was used to feed water at a rate of 50 mL/h using two thin tubes 3114. As the water was pumped, the two fabrics presented very different behaviors. The conventional moisture-wicking polyester became wet and spread the moisture over the entire surface of the fabric. The fabric with the fluidic channel patterns quickly conducted the water from the inner surface layer (the back of the fabric) to the outer dripping point where droplets were formed on the outer surface of the fabric after approximately 10 seconds.

After 2 minutes, the conventional moisture-wicking polyester 3104 became completely saturated and kept all of the water inside of the fabric. The moisture can be identified by the darker color on the fabric square. Conversely, the fabric with the fluidic network 3102 contained the moisture in its fluidic channels 3106. As the moisture collected within the fluidic channels 3106 and flowed down the length of the channels to the dripping point 3108, droplets 3112 continuously dripped off of the fabric and formed a small puddle at the bottom of the plastic board (not shown), demonstrating the fluid management of the fluidic network structure.

A more quantitative measurement was also conducted to compare different characteristics of the two fabric samples when wetted by water completely, including weight pickup ratio, vapor permeability when saturated, wet area ratio of the fabric both inside and outside as well as the drying time. As can be seen from Table 2, for each characteristic parameter, the fabric with the fluidic pattern demonstrated greater advantages over the conventional moisture-wicking (Control) scheme. It should be noted that this data corresponds to the specific fluidic channel design as shown in FIG. 30A through FIG. 31 and other designs may possess different values.

A condensation 3208 control fabric was constructed following the design 3200 shown in FIG. 32A. The fluidic channel network was designed to facilitate the removal of all droplets larger than 3 mm. Liquid-absorptive polyester fabric pattern strips 3202 were cut by a laser engraver (VLS, Universal Laser) and bonded to a liquid-repellent substrate fabric 3204 (woven hydrophobic polyester) by instant glue.

The fabric sample was placed vertically on a plastic board 3206 and a water vapor flow was generated utilizing a humidifier (model no. 7144, Air-o-Swiss) on the “high” power setting as shown in the image 3208 shown in FIG. 32B. After 6 minutes, the vapor was stopped and the weight and drying time of the sample material were recorded. An original liquid-repellant polyester fabric with the same shape was prepared as a control for comparison.

The results are shown in Table 3. The fabric with the fluidic channels contained 25% less water than the control fabric at the conclusion of the experiment.

Moreover, fewer droplets and smaller droplets (higher surface-to-volume ratio) on the sample resulted in a much quicker drying time (110 min compared with 210 min). During the experiment, it was observed that all of the excess droplets rolled off at the dripping point of the fluidic pattern on the sample fabric. However on the control fabric sample, the droplets grew to a bigger size (˜4 mm) and ran off of the fabric at random locations. These results demonstrate the effectiveness of the fluidic channel structure in managing condensation.

Published research on the sweat rate mapping of the human body during exercise indicates that the sweat rate at different regions of the body varies dramatically. The sweat rate on the forehead can be 1710 gm⁻²h⁻¹ which is about 3 times that of the sweat rate on the middle chest region (546 gm⁻²h⁻¹). This non-uniformity suggests that the fabric over the body surface should be at different moisture levels during exercise. However, conventional sportswear, constructed with moisture-wicking fabric, absorbs all of the sweat generated on different areas of the body (including the sweat from head) and then wicks the moisture to adjacent dry areas. This can result in most areas of the shirt becoming uniformly saturated even though several areas (including side chest, waist, lower belly, etc.) have slower sweat rates and should remain drier if only absorbing the sweat underneath of that particular region.

For example, the chest area of a wearer's sportswear can become saturated and sticky very quickly during exercise. However, this area of the shirt is mainly soaked by sweat generated on the head which flows down along the neck to the collar of the shirt and spreads over the chest area of the shirt. Accordingly, FIG. 33A and FIG. 33B show images of the front 3300 and back 3302 of a shirt fabricated with fluidic channel networks 3304 that are repeated throughout the garment.

Since each pattern is separated by a liquid-repellent barrier and the removal capacity of each unit is independent, the regions with a lower sweat rate 3306 will be kept much drier. The shirt is able to remove the sweat that is generated on the torso by dripping the sweat away at the dripping point 3308 of each fluidic channel network 3304. Such a fabric structure can be applied to shirts, shorts, pants, tank-tops, sports bras, underwear, etc.

The geometry and arrangement of the fluidic channel networks can be positioned to fit the mapping of the sweat rate regions of the body to provide comfort during exercise. The positioning involves the appropriate arrangement of these networks related to the physiological character and comfort of the human body and can even be customized to suit a particular wearer. Further aspects of the presented technology will be brought out in the following examples of several categories of apparel, wherein the descriptions are for the purpose of fully disclosing preferred embodiments of the technology for applying the fluidic network structure to apparel without placing limitations thereon. Although the fluidic channel and dripping point geometries can vary greatly, the following examples are for the purpose of illustrating the positioning of the fluidic channels and dripping points for different applications. Therefore, the channel and dripping points in the following figures have been simplified.

FIG. 34A and FIG. 34B illustrate how the fluidic channels 3400 on a shirt may be arranged so that the formation and dripping of the droplets become unobvious. This embodiment may be useful for someone who finds multiple droplets rolling down the outer surface of their garment embarrassing or uncomfortable. In this design, the fluidic channels 3400 are specifically arranged to remove the sweat from the body and drip it away at the bottom of the shirt. The fluidic channels 3400 are extended vertically to cover most of the shirt. The bottom transporting channels 3402 are connected with the vertical fluidic channels and carry the moisture to the two dripping points 3404 at the bottom of the shirt where the moisture can be released and dripped away. The wind flow generated when the wearer is moving may facilitate the release of the droplets as well.

The arrangement of the fluidic channels can be designed to specifically remove the sweat generated on different sections of the human body. In doing so, a garment with a fluidic network structure can remove the moisture from one location utilizing a minimum area of the garment which maintains comfort for the wearer over a long period of time (e.g. during an exercise session or sports match). Since the liquid-repellent regions are completely dry, the permeability of this region remains higher which is beneficial for the evaporative cooling effect on the skin. In addition, the temperature of the liquid-repellent fabric remains higher which is beneficial for reducing the unpleasant chill that can be experienced during and after a workout. According to one test, the temperature of the dry fabric measured 7° C. warmer than a soaked fabric.

Referring to FIG. 35A, the front side of the shirt 3500 in this example has three main separated liquid-absorptive regions (the detailed fluidic channel structure inside the region is not limited to the simplified design shown here and can be any design that works best for a given wearer or application). The middle region 3502 begins at the collar area and extends to the bottom of the front side of the shirt. The left and right side regions 3504, 3506 begin at the shoulders of the shirt and cover the chest area of the human body. These three regions are separated from each other by liquid-repellent regions 3508 that extend throughout the fabric thickness. The center region 3502 of the garment is for collecting and conducting the sweat running down from the head and neck to the bottom of the shirt without spreading it out to the chest or abdomen area. The other two regions 3504, 3506 are for transporting the sweat generated on the chest area to the dripping points 3518, 3520 on the sides of the garment. The abdomen region 3508 of the shirt remains mostly liquid-repellent since it is infrequently in contact with the torso in many postures during sports activities.

Referring to FIG. 35B, the back side of this example 3500 has an upper liquid-absorptive region 3510 and a middle liquid-absorptive region 3512. The upper region 3510 is connected with the collar region on the front side and extends down and across to the sides of the shirt. The middle region 3512 is located below region 3510 and covers the middle region of the back and also wraps around the side of the shirt. The two liquid-absorptive regions 3510, 3512 are separated by a liquid-repellent region 3514 that penetrates through the fabric. The upper liquid-absorptive region 3510 collects the sweat mainly from the head and neck areas and the middle region 3512 removes the sweat from the upper back area of the body and channels the sweat to the sides of the shirt. The lower portion of the garment that covers the lower back/waist area is left completely liquid-repellent since this section of the shirt infrequently touches the skin during many workouts.

FIG. 36A and FIG. 36B illustrate another embodiment 3600 of a detailed liquid-absorptive channel 3602 configuration on a shirt following the general region arrangement shown in the previous embodiment 3500. The back of each channel can be partially liquid-repellent according to the previous descriptions. The arrows indicate the direction of the fluid flow as well as the location of the dripping points 3612, 3614, 3616, 3618, 3630, 3632.

Referring to FIG. 36A, the front side of the shirt in this embodiment 3600 has three main liquid-absorptive regions. The left and right liquid-absorptive channel chest regions 3606, 3608 are separated from the main liquid-absorptive channel 3610 by a liquid-repellent region 3620, 3622. The main liquid-absorptive channel 3610 runs vertically down the front side of the shirt and carries fluid from the head and neck region 3604 to the two bottom dripping points 3612, 3614. The left liquid-absorptive channel chest region 3606 and the right liquid-absorptive channel chest region 3608 carry fluid from the chest to the dripping points 3616, 3618 on the side of the shirt. The abdomen regions of the front 3620, 3622 and back 3624 of the shirt remain mostly liquid-repellent since these regions are infrequently in contact with the torso in many postures during sports activities.

Referring to FIG. 36B, the back of the shirt has two main separated liquid-absorptive regions 3626, 3628. The liquid-absorptive head/neck channel region 3626 carries fluid from the head and neck to the side dripping points 3630, 3632.

In the embodiment 3700 shown in FIG. 37A through FIG. 37C, the sleeves 3706 of the shirt are incorporated into the fluidic network design shown in FIG. 36A and FIG. 36B. FIG. 37C shows a side view of the shirt embodiment 3700 with the liquid-absorptive channels 3702 running along the shoulder and down the upper arm area of the shirt. Fluid is carried from the head and neck across the shoulder and down to the dripping point 3704 on the end of the sleeve.

In some situations, it may be advantageous to keep the fluid from dripping off of the garment and onto a surface, for example in a basketball, badminton or racquetball game. For these situations, the dripping points at the end of the liquid-absorptive channel networks can be connected to a liquid-absorptive panel which can hold the fluid (e.g. sweat), which can be removed to a desired location or held in the panels to evaporate. FIG. 38A and FIG. 38B show a diagram of the front and back, respectively, of a shirt with a bottom liquid-absorptive panel 3802 and two side liquid-absorptive panels 3804, 3806 and a liquid-absorptive channel network design that is identical to the example 3600 previously described in FIG. 36A and FIG. 36B. As these panels are on the sides of the shirt, the wearer remains comfortable during sports activity.

FIG. 38C is an image of the shirt described in FIG. 38A with the liquid-absorptive panel on the bottom 3802 shown collecting the sweat (dark color) from the wearer after exercise instead of dripping the sweat away. FIG. 38D is an image of the shirt described in FIG. 38A and FIG. 38B where the side panels are shown collecting the sweat from the wearer after exercise instead of dripping the sweat away. In both images, the majority of the shirt is shown as dry, except for the liquid-absorptive channels 3808 and side panel 3806.

In an alternative to the example described in FIG. 38A through FIG. 38D, the liquid-absorptive side panels 3804, 3806 can be constructed as a material that is different than the rest of the shirt. Also, the liquid-absorptive side panels 3804, 3806 and bottom liquid-absorptive panel 3802 can be made detachable and replaced with a dry panel when they become saturated with fluid.

In another configuration of the previously described embodiment 3800, the absorbent panels can be reversible where they can be switched between a panel with dripping points connected to the channel network and the liquid-absorptive (non-dripping) panel. The wearer can choose the appropriate mode of sweat management according to different needs of the activities.

The embodiment 3900 shown in FIG. 39A and FIG. 39B, has a front side that has a liquid-absorptive region 3902 which covers both the collar and chest area and extends to the side dripping points 3906, 3908 of the shirt while the abdomen region 3904 is kept liquid-repellent. The back side, shown in FIG. 39B, has the same liquid-absorptive region 3902 covering both the collar and upper back area while the lower back area 3904 remains liquid-repellent.

FIG. 40 shows a diagram 4000 of a fluidic channel network in the shape of a tree pattern on a shirt following the simplified channel region arrangement depicted in FIG. 39A. The crown region of the tree shape consists of several randomly distributed short fluidic channels 4002 which carry fluid from the head, neck and chest regions down to the trunk 4004 of the tree shape. The fluid then travels through the root shaped fluidic channels 4006 and off of the shirt at the dripping points 4008.

In another embodiment 4100, the front panel of the shirt has three regions of liquid-absorptive channels separated by liquid-repellent regions as seen in FIG. 41A. This design can be useful when the garment is being worn as a compression garment that fits tightly against the body. The top liquid-absorptive channel region 4102 is connected with the collar region of the shirt and carries fluid to the underarm area dripping points 4104, 4106. The center liquid-absorptive region 4108 covers the chest area and carries fluid to the mid-abdomen side dripping points of the shirt 4110, 4112. The bottom-abdomen liquid-absorptive region 4114 covers the abdomen area and carries fluid to the lower portion of the shirt to drip off the bottom.

The back panel of the shirt, shown in FIG. 41B, has 4 liquid-absorptive regions separated by a liquid-repellent region. The top liquid-absorptive region 4116 carries fluid from the collar and shoulder regions of the shirt to the upper side dripping points 4118, 4120 of the garment. The left 4122 and right 4124 center liquid-absorptive regions cover the upper back and carry fluid to the lower sides of the shirt to the dripping points 4126, 4128. The gap between these two regions is the liquid-repellent region 4130 and keeps the middle regions dry with maximum gas permeability for a cooling effect on the spine. The bottom liquid-absorptive region 4132 covers the lower back and waste area and carries fluid to the bottom of the shirt.

In another embodiment, the garment configuration may incorporate liquid-absorptive regions that transport sweat away from temperature sensitive areas on the body to reduce the post-chill feel after exercise. Temperature sensitive areas are those regions that are more sensitive to temperature changes, including the spine, the front of the chest, below the breasts, the armpits, etc. The dryness of these areas after exercise will reduce the unpleasant chill that wet fabric can cause after exercise. This garment configuration can require less liquid-absorptive regions which can reduce big temperature drops on these areas after exercise due to the evaporation cooling effect of the fabric. Alternatively, more liquid-absorptive regions can be arranged over temperature sensitive areas to provide a stronger cooling feel over these regions during exercise.

In another embodiment, the fluidic network structure may follow the geometry or profile of the human body. The convex regions of the human body (e.g. chest, shoulder, and belly) can be covered with liquid-absorptive channels while the concave regions (e.g. lower back) of the human body can be left liquid-repellent or can also be covered with the liquid-absorptive channels. The gender of the wearer can also affect the apparel design. The different body structure between males and females can result in different regions being utilized for transporting and removing sweat.

In another embodiment, the number of liquid-absorptive channels on a garment can be customized according to a specific wearer's body areas and perspiration rates. For the body regions where the wearer perspires slowly, more liquid-repellent areas can be arranged in order to leave a limited amount of sweat to evaporate off of their skin for cooling. For a wearer with a high perspiration rate, more liquid-absorptive channels can be placed in a manner to use the fluidic transport mechanism (gravity, compression or surface tension forces) to remove the larger volume of sweat more quickly.

In another embodiment, a garment with a fluidic network structure can be utilized for pre-cooling a wearer before an activity or just cooling a wearer in warm temperatures. The garment can be immersed in water before the wearer puts it on to provide a longer cooling effect for the wearer. Since the wet area of the garment can be limited, there is only a small increase in the weight of the garment. Moreover, the chilling feel of the garment can be controlled by adjusting the ratio of the wet area to the dry area of the garment.

The position, number of liquid-absorptive channels, direction of the fluid flow, and liquid-repellant regions are not limited to the examples in the present description. The configuration of the fluidic network structure can depend on how tight the garment is, the wearer's posture during a particular activity, a desired esthetic, etc. Additionally, the front and back sides of a shirt, etc. can be separated and the garment can be constructed to have only the front or the back side modified for moisture management.

FIG. 42A shows a diagram of an example fluidic network structure as applied to a pair of shorts 4200. On the waist area of the short, fluidic channels 4202 can be constructed so that the sweat flowing down from the upper body during movement can be collected by the channels 4202 on the waistband and transported to the sides of the short. The sweat can then flow down to the edge of the fluidic channel structure and drip away at the dripping points 4204, 4206. FIG. 42B is an image of the front of the shorts shown in FIG. 42A. FIG. 42C is an image of the side of the shorts shown in FIG. 42A. The rest of the shorts 4108 can be left completely liquid-repellent as the wearer may have underwear on underneath the shorts. Without the fluidic channels on the waistband, a large amount of sweat may soak the shorts, including the wearer's underwear.

FIG. 43A shows a diagram illustrating another version 4300 of the fluidic channel configuration as applied to a pair of shorts where the fluidic channels 4302 extend to the sides of the leg region.

FIG. 44 is a diagram illustrating another fluidic channel network configuration on a pair of shorts 4400 where fluid-absorptive channels 4402 cover the shorts to transport the sweat to the sides of the shorts and drip it away via the dripping points 4404, 4406. The circles 4408 are an example of what the fluidic inlets might look like on the inner layer of the shorts.

FIG. 45 shows a diagram of one embodiment 4500 of a sock with a liquid-absorptive fluidic network structure that has fluidic channels 4502 that carry the sweat running down the leg to the sides of the sock and drip it away via dripping points 4504, 4506. The socks and shoes of a wearer can become saturated during exercise not only because of the sweat generated by foot itself, but also from the sweat running down the legs into the shoes. Incorporating a fluidic channel into socks can largely reduce the body sweat running into the shoes, making the feet uncomfortable.

FIG. 46A shows a diagram of one embodiment 4600 of a headband with a liquid-absorptive fluidic network. The headband comprises liquid-absorptive channels 4602 and liquid-repellent areas 4604. The liquid-absorptive channels 4602 are arranged in a pattern that carries the sweat generated on the forehead to the two dripping points 4606, 4608 on the sides of the face. The liquid-absorptive channels 4602 will prevent the sweat from running into eyes and burning. Following the gravity-driven flow principles, the liquid-absorptive channels 4602 will continuously remove the sweat to provide a cool and comfortable feel for the wearer and will prevent the wearer from having to wipe their forehead. FIG. 46B through FIG. 46D are images of the embodiment 4600 shown in FIG. 46A. This headband is composed of the same fabric for activewear and is much thinner and lighter compared to the conventional terrycloth materials. It can be utilized as a standard sweatband for both sports and industry applications. Such a sweat directing structure can be integrated inside of a cap, helmet or other similar apparel.

When designing a fluidic network material for use with an exercise garment, the human posture during a particular exercise should be carefully observed in order to provide the right fluidic channel configuration. For example, the arrangement of the fluidic channels 4702 on a cycling garment 4700 should be very different from a running shirt, as the upper body of the bicycle rider will be nearly horizontal instead of vertical most of the time, as shown in FIG. 47. The fluidic channels 4702 on the back and front of the garment are mainly vertical when the athlete stays in the riding posture. The dripping point 4704 is at the bottom of the pants to ensure gravitational-force driven dripping.

FIG. 48A and FIG. 48B show diagrams of one embodiment 4800 of a tent with a liquid-absorptive fluidic network on the interior. The fluidic network structure is helpful for managing condensation that can be a problem existing in current tent designs. When a camper stays in the tent for a prolonged period of time, the water vapor generated from the camper's breath can condense on the inside surface of the tent. The moisture can accumulate up to 1 L per 24 hours. With appropriate fluid management using liquid-absorptive channels 4802, the condensed moisture won't slide randomly down from the roof of the tent to form puddles of water around the floor of the tent. Instead, the moisture can be channeled to a desired location or absorbed with a liquid-absorptive pad and taken away from the tent. The fluidic network is also useful as applied to tents to help keep the tent dry before the tent is packed away. This avoids excess moisture and mold from growing in the packed tent.

In FIG. 48A, the fluidic network structure is arranged from the top 4804 of the roof to the bottom 4806 of the tent. For simplicity of illustration, only one section of the fluidic pattern is shown, however, the fluidic network would cover the four sections of the tent. The fluidic network structure can reduce the volume of water that accumulates on the roof, according to the principles previously described. In FIG. 48B, the tent has longer extended half-cylindrical fluid-absorptive channels 4802 and the interior fluidic network arrangement is different. The short “ribs” 4808 of the channels are symmetric around the top of the roof and the long transporting channels 4810 are on the sidewalls 4812 with an angle towards the bottom end of the tent where the moisture can be collected.

From the description herein, it will be appreciated that that the present disclosure encompasses multiple embodiments which include, but are not limited to, the following:

1. An apparatus for managing fluid, the apparatus comprising: a substrate having a first region with a first wettability and having a second region with a second wettability; wherein the second region is adjacent to the first region; wherein the second wettability is greater than the first wettability; wherein the second region forms a fluidic channel having a fluid flow direction; and wherein the fluidic channel is configured such that fluid moves along the fluidic channel by a force applied in the flow direction in response to fluid contacting the fluidic channel.

2. The apparatus of any preceding embodiment, wherein the force applied is one or more of gravitational force, compression force, capillary force or surface tension force.

3. The apparatus of any preceding embodiment, further comprising: a dripping point coupled to the fluidic channel; wherein the dripping point is positioned near the lowest gravitational point of the fluidic channel; wherein the substrate is configured such that fluid collects at the dripping point and drips off of the substrate; and wherein the dripping point is configured to slow down or speed up a rate at which the fluid drips off of the substrate.

4. The apparatus of any preceding embodiment, wherein the fluidic channel is interrupted by a liquid-repellent gap configured for unidirectional fluid flow.

5. The apparatus of any preceding embodiment: wherein the first wettability is liquid-repellent, creating a liquid-repellent region; and wherein the second wettability is liquid-absorptive, creating a liquid-absorptive region.

6. The apparatus of any preceding embodiment, wherein the fluid contacting the fluidic channel is facilitated by a compression force generated by the liquid-repellent region being in close contact with a fluid producing surface.

7. The apparatus of any preceding embodiment, wherein the substrate comprises multiple contact angles within the liquid-absorptive region, creating a wettability gradient.

8. The apparatus of any preceding embodiment, wherein the substrate comprises multiple contact angles within the liquid-repellent region, creating a wettability gradient.

9. The apparatus of any preceding embodiment, wherein a plurality of fluidic channels are configured to manage condensation.

10. The apparatus of any preceding embodiment, further comprising: a third region in the substrate having a third wettability; wherein the third wettability is liquid-absorptive; wherein the third region is positioned near the lowest gravitational point of the fluidic channel; and wherein the third region is configured to collect fluid and prevent it from dripping off of the substrate.

11. The apparatus of any preceding embodiment, wherein the third region is configured to be removable.

12. The apparatus of any preceding embodiment, wherein the substrate further comprises: a first surface layer and a second surface layer; wherein the first surface layer comprises one or more fluidic channels; and a thickness of the substrate in between the first and second surface layers; wherein the fluidic channel penetrates the thickness of the substrate at one or more locations on the second surface layer; and wherein the fluidic channel is configured such that fluid moves from the second surface layer to the first surface layer along the fluidic channel.

13. The apparatus of any preceding embodiment, further comprising: a dripping point coupled to the fluidic channel; wherein the dripping point is positioned near the lowest gravitational point of the fluidic channel; wherein the substrate is configured such that fluid collects at the dripping point and drips off of the substrate; and wherein the dripping point is configured such that the dripping point is positioned only on the second surface layer, preventing fluid from contacting the first surface layer as it drips off of the substrate.

14. The apparatus of any preceding embodiment, wherein a portion of the channel that penetrates the thickness of the substrate is smaller at the second surface layer and gets larger as it reaches the first surface layer.

15. The apparatus of any preceding embodiment, wherein a layer of liquid-repellant material is positioned on top of the first surface layer such that the fluidic channels are invisible when wet or dry.

16. The apparatus of any preceding embodiment, wherein the fluidic channel extends past the second surface layer to form a support structure.

17. The apparatus of any preceding embodiment, wherein the fluidic channel is a component of a garment.

18. The apparatus of any preceding embodiment, wherein a plurality of fluidic channels form a design on the garment.

19. The apparatus of any preceding embodiment, wherein a plurality of fluidic channels are configured in the garment to manage perspiration on a human body.

20. The apparatus of any preceding embodiment: wherein the garment is a shirt; wherein a first plurality of fluidic channels forms a neck region in the shirt configured to transport perspiration away from a person's neck to the bottom of the shirt where the perspiration drips off of the shirt; wherein a second plurality of fluidic channels forms one or more chest regions in the shirt configured to transport perspiration from a person's chest to one or more sides of the shirt where the perspiration drips off of the shirt; and wherein a third plurality of fluidic channels forms one or more back regions in the shirt configured to transport perspiration from a person's chest to one or more sides of the shirt where the perspiration drips off of the shirt.

21. The apparatus of any preceding embodiment, wherein a fourth plurality of fluidic channels forms one or more sleeve regions in the shirt configured to transport perspiration from a person's head and neck to the bottom of the sleeve where the perspiration drips off of the shirt.

22. An apparatus for managing fluid, the apparatus comprising: a substrate having a first liquid-absorptive region with a first wettability and having a second liquid-absorptive region with a second wettability; wherein the second liquid-absorptive region is adjacent to the first liquid-absorptive region; wherein the second wettability is greater than the first wettability; wherein the first and second liquid-absorptive regions form a wettability gradient for fluidic flow; and wherein when fluid contacts the substrate, the fluid moves along the gradient from the first liquid-absorptive region to the second liquid-absorptive region.

23. The apparatus of any preceding embodiment, wherein the substrate comprises multiple contact angles within the second liquid-absorptive region, creating a wettability gradient.

24. The apparatus of any preceding embodiment, wherein the substrate comprises multiple contact angles within the first liquid-absorptive region, creating a wettability gradient.

25. The apparatus of any preceding embodiment, wherein the fluidic flow in the second liquid-absorptive region is affected by one or more of gravitational force, compression force, capillary force or surface tension force.

26. An apparatus for managing fluid, the apparatus comprising: (a)

a plurality of fluidic channels; (b) each of the fluidic channels comprising: (i) a substrate having a first region with a first wettability and having a second region with a second wettability; (ii) wherein the second region is adjacent to the first region; (iii) wherein the second wettability is greater than the first wettability; (iv) wherein the second region forms the fluidic channel having a fluid flow direction; (v) wherein the fluidic channel is configured such that fluid moves along the fluidic channel by a force applied in the flow direction in response to fluid contacting the fluidic channel; and (c) wherein the plurality of fluidic channels is arranged in a fluidic network structure.

27. A method for managing fluid, the method comprising: creating a first region with a first wettability in a substrate; and creating a second region with a second wettability in the substrate; wherein the second wettability is greater than the first wettability; and wherein the second region forms a fluidic channel having a fluid flow direction; and configuring the fluidic channel such that fluid moves along the fluidic channel by a force applied in the flow direction in response to fluid contacting the fluidic channel.

28. The method of any preceding embodiment, wherein the force applied is one or more of gravitational force, compression force, capillary force or surface tension force.

29. The method of any preceding embodiment, wherein the first region and the second region are created using a printing process.

30. The method of any preceding embodiment, wherein the first region and the second region are created using a knitting process.

Although the description herein contains many details, these should not be construed as limiting the scope of the disclosure but as merely providing illustrations of some of the presently preferred embodiments. Therefore, it will be appreciated that the scope of the disclosure fully encompasses other embodiments which may become obvious to those skilled in the art.

In the claims, reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” All structural, chemical, and functional equivalents to the elements of the disclosed embodiments that are known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the present claims. Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed as a “means plus function” element unless the element is expressly recited using the phrase “means for”. No claim element herein is to be construed as a “step plus function” element unless the element is expressly recited using the phrase “step for”.

	TABLE 1
						Pressure	Pressure
					Pore Size	(100%	(~50%
			Weight	Thickness	(estimated)	penetration)	penetration)
	Structure	Composition	(g/m2)	(mm)	(μm)	(Pa)	(Pa)
A	Single-knit	92% polyester	168	0.508	98.4	740	250
	Jersey	8% spandex
B	Single-knit	92% polyester	187	0.772	40	>1000	650
	Jersey	8% spandex
C	Interlock	100%	175	0.574	104	990	400
		polyester

	TABLE 2
	Fabric patterned		Improvement
	with fluidic		(Patterned-
	channels	Control	control)/control
Wet pickup ratio	50%	188%	73% lighter when
(WPU %)			wet
Vapor Permeability	1680	1340	25% more
when saturated			permeable when
(g · m−2day−1)†			wet
Wet area ratio	43%	100%	57% more dry
(outside)			area
Wet area	8%	100%	92% more dry
ratio(inner)			area
Drying time(min)‡	60	210	70% Faster
†Experiment was conducted in 23° C. and 40% humidity
‡Experiment was conducted in 25° C. and 37% humidity

	TABLE 3
		Water
		Weight		Drying
	Weight (g)	Increase	Weight increase	time
Sample	Before	After	(g)	percent (%)	(min)†
Patterned	0.57	1.32 ± 0.20	0.75	132.28 ± 35.58	110
Original	0.35	1.36 ± 0.13	1.01	288.57 ± 37.42	210

Claims

1. An apparatus for managing fluid, the apparatus comprising: a substrate having a first region with a first wettability and having a second region with a second wettability;wherein the second region is adjacent to the first region;wherein the second wettability is greater than the first wettability;wherein the second region forms a fluidic channel having a fluid flow direction; andwherein the fluidic channel is configured such that fluid moves along the fluidic channel by a force applied in the flow direction in response to fluid contacting the fluidic channel.

2. The apparatus of claim 1, wherein the force applied is one or more of gravitational force, compression force, capillary force or surface tension force.

3. The apparatus of claim 1, further comprising: a dripping point coupled to the fluidic channel;wherein the dripping point is positioned near the lowest gravitational point of the fluidic channel;wherein the substrate is configured such that fluid collects at the dripping point and drips off of the substrate; andwherein the dripping point is configured to slow down or speed up a rate at which the fluid drips off of the substrate.

4. The apparatus of claim 1, wherein the fluidic channel is interrupted by a liquid-repellent gap configured for unidirectional fluid flow.

5. The apparatus of claim 1: wherein the first wettability is liquid-repellent, creating a liquid-repellent region; andwherein the second wettability is liquid-absorptive, creating a liquid-absorptive region.

6. The apparatus of claim 5, wherein the fluid contacting the fluidic channel is facilitated by a compression force generated by the liquid-repellent region being in close contact with a fluid producing surface.

7. The apparatus of claim 5, wherein the substrate comprises multiple contact angles within the liquid-absorptive region, creating a wettability gradient.

8. The apparatus of claim 5, wherein the substrate comprises multiple contact angles within the liquid-repellent region, creating a wettability gradient.

9. The apparatus of claim 5, wherein a plurality of fluidic channels are configured to manage condensation.

10. The apparatus of claim 1, further comprising: a third region in the substrate having a third wettability;wherein the third wettability is liquid-absorptive;wherein the third region is positioned near the lowest gravitational point of the fluidic channel; andwherein the third region is configured to collect fluid and prevent it from dripping off of the substrate.

11. The apparatus of claim 10, wherein the third region is configured to be removable.

12. The apparatus of claim 1, wherein the substrate further comprises: a first surface layer and a second surface layer;wherein the first surface layer comprises one or more fluidic channels; anda thickness of the substrate in between the first and second surface layers;wherein the fluidic channel penetrates the thickness of the substrate at one or more locations on the second surface layer; andwherein the fluidic channel is configured such that fluid moves from the second surface layer to the first surface layer along the fluidic channel.

13. The apparatus of claim 12, further comprising: a dripping point coupled to the fluidic channel;wherein the dripping point is positioned near the lowest gravitational point of the fluidic channel;wherein the substrate is configured such that fluid collects at the dripping point and drips off of the substrate; andwherein the dripping point is configured such that the dripping point is positioned only on the second surface layer, preventing fluid from contacting the first surface layer as it drips off of the substrate.

14. The apparatus of claim 12, wherein a portion of the channel that penetrates the thickness of the substrate is smaller at the second surface layer and gets larger as it reaches the first surface layer.

15. The apparatus of claim 12, wherein a layer of liquid-repellant material is positioned on top of the first surface layer such that the fluidic channels are invisible when wet or dry.

16. The apparatus of claim 12, wherein the fluidic channel extends past the second surface layer to form a support structure.

17. The apparatus of claim 1, wherein the fluidic channel is a component of a garment.

18. The apparatus of claim 17, wherein a plurality of fluidic channels form a design on the garment.

19. The apparatus of claim 17, wherein a plurality of fluidic channels are configured in the garment to manage perspiration on a human body.

20. The apparatus of claim 19: wherein the garment is a shirt;wherein a first plurality of fluidic channels forms a neck region in the shirt configured to transport perspiration away from a person's neck to the bottom of the shirt where the perspiration drips off of the shirt;wherein a second plurality of fluidic channels forms one or more chest regions in the shirt configured to transport perspiration from a person's chest to one or more sides of the shirt where the perspiration drips off of the shirt; andwherein a third plurality of fluidic channels forms one or more back regions in the shirt configured to transport perspiration from a person's chest to one or more sides of the shirt where the perspiration drips off of the shirt.

21. The apparatus of claim 20, wherein a fourth plurality of fluidic channels forms one or more sleeve regions in the shirt configured to transport perspiration from a person's head and neck to the bottom of the sleeve where the perspiration drips off of the shirt.

22. An apparatus for managing fluid, the apparatus comprising: a substrate having a first liquid-absorptive region with a first wettability and having a second liquid-absorptive region with a second wettability;wherein the second liquid-absorptive region is adjacent to the first liquid-absorptive region;wherein the second wettability is greater than the first wettability;wherein the first and second liquid-absorptive regions form a wettability gradient for fluidic flow; andwherein when fluid contacts the substrate, the fluid moves along the gradient from the first liquid-absorptive region to the second liquid-absorptive region.

23. The apparatus of claim 22, wherein the substrate comprises multiple contact angles within the second liquid-absorptive region, creating a wettability gradient.

24. The apparatus of claim 22, wherein the substrate comprises multiple contact angles within the first liquid-absorptive region, creating a wettability gradient.

25. The apparatus of claim 22, wherein the fluidic flow in the second liquid-absorptive region is affected by one or more of gravitational force, compression force, capillary force or surface tension force.

26. An apparatus for managing fluid, the apparatus comprising: (a) a plurality of fluidic channels;(b) each of the fluidic channels comprising: a substrate having a first region with a first wettability and having a second region with a second wettability;(ii) wherein the second region is adjacent to the first region;(iii) wherein the second wettability is greater than the first wettability;(iv) wherein the second region forms the fluidic channel having a fluid flow direction;(v) wherein the fluidic channel is configured such that fluid moves along the fluidic channel by a force applied in the flow direction in response to fluid contacting the fluidic channel; and(c) wherein the plurality of fluidic channels is arranged in a fluidic network structure.

27. A method for managing fluid, the method comprising: creating a first region with a first wettability in a substrate; andcreating a second region with a second wettability in the substrate;wherein the second wettability is greater than the first wettability; andwherein the second region forms a fluidic channel having a fluid flow direction; andconfiguring the fluidic channel such that fluid moves along the fluidic channel by a force applied in the flow direction in response to fluid contacting the fluidic channel.

28. The method of claim 27, wherein the force applied is one or more of gravitational force, compression force, capillary force or surface tension force.

29. The method of claim 27, wherein the first region and the second region are created using a printing process.

30. The method of claim 27, wherein the first region and the second region are created using a knitting process.