BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1A-1C are schematic illustrations of one embodiment of the device described herein, where the device is shown alone (FIGS. 1A-1B) and mated with a microfluidic device (FIG. 1C);
FIGS. 1D and 1E are schematic illustrations of the spiral well used in some embodiments of the device;
FIGS. 2A-2C are schematic illustrations of a single channel of one embodiment of the device described herein, showing the positions of two pistons in the channel before release of a fluid therefrom (FIG. 2A), during release of a fluid (FIG. 2B), and after release of a fluid (FIG. 2C);
FIGS. 3A-3B are schematic illustrations of a single channel of one embodiment of the device described herein, showing the positions of a single piston in the channel with respect to a channel aperture;
FIGS. 4A-4D are schematic illustrations of a ratchet component for actuating movement of pistons in a channel of one embodiment of the device;
FIGS. 5A-5D are schematic illustrations of an embodiment for actuating movement of pistons in a channel of one embodiment of the device, where a sliding bar is positioned in the fluid handling device;
FIGS. 6A-6D are schematic illustrations of another embodiment for actuating movement of pistons in a channel of one embodiment of the device, where a movable rod is positioned in the fluid handling device;
FIGS. 7A-7D are schematic illustrations of another embodiment for initiating movement of pistons in a channel the fluid handling device;
FIG. 8 shows a method of using the fluid handling device, where a fluid in a channel is moved to an adjacent channel for mixing, prior to introduction of the fluid into a microfluidic device;
FIGS. 9A-9B show another embodiment of the fluid handling device for mixing fluids; and
FIGS. 10A-10C show an embodiment of a device for dispensing one or more fluids.
DETAILED DESCRIPTION
I. Definitions
The term “microfluidic” as used herein refers to structures or devices through which one or more fluids are capable of being passed or directed and at least one fluid channel having a cross-sectional dimension of less than about 1000 microns (1 millimeter).
“Channel”, as used herein, means a feature on or in a microfluidic device substrate that can at least partially confine and direct the flow of a fluid. Preferably a channel has an aspect ratio (length to average cross sectional dimension) of at least 2:1, more typically at least 3:1, 5:1, or 10:1. The feature can be a groove or other indentation of any cross-sectional shape (curved, square or rectangular) and can be covered or uncovered. A channel generally will include characteristics that facilitate control over fluid transport, e.g., structural characteristics (an elongated indentation) and/or physical or chemical characteristics (hydrophobicity vs. hydrophilicity) or other characteristics that can exert a force (e.g., a containing force) on a fluid. The channel may be of any size, for example, having a largest dimension perpendicular to fluid flow of less than about 5 or 2 millimeters, or less than about 1 millimeter, or less than about 500 microns, less than about 200 microns, less than about 100 microns, or less than about 50 or 25 microns. Larger channels, tubes, etc. can be used in the device for a variety of purposes, e.g., to store fluids in bulk or to direct fluid flow to a certain region of the device or of a microfluidic device. The dimensions of the channel may also be chosen, for example, to allow a certain volumetric or linear flow rate of fluid in the channel. Of course, the number of channels and the shape of the channels can be varied by any method known to those of ordinary skill in the art.
“Integral”, as used herein, means that the portions are joined in such a way that they cannot be separated from each other without cutting or breaking the components from each other.
The term “plug” refers to matter in the shape of a cylinder and having the diameter of the inside of the channel. A plug can be a solid object in the channel, or a volume of fluid that occupies a space in the channel, the space being defined by pistons in the channel.
In the claims, as well as in the specification, all transitional phrases such as “comprising”, “including”, “having”, “containing”, “involving”, “composed of”, “made of”, “formed of” and the like are to be understood to be open-ended, i.e. to mean including but not limited to. The transitional phrases “consisting of” and “consisting essentially of” are understood to be closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures, section 2111.03.
II. Device
In a first aspect, a device that interfaces with, or is an integral part of, a microfluidic device for introduction of a fluid from the device to the microfluidic device is provided. In another aspect, a device capable of delivering one or more discrete plugs of fluid is described, the device optionally capable of mating with a microfluidic device. These various aspects will now be discussed.
FIGS. 1A-1B are plan views of a device designed to interface with a microfluidic device and introduce a fluid into the microfluidic device. With initial reference to FIG. 1A, device 10 is formed on a (preferably planar) substrate 12. A channel 14 is formed in or on the substrate, the channel extending between an inlet port 16 and an outlet port 18. In this embodiment, the inlet and outlet ports are disposed at first and second ends, 20, 22, respectively, of the substrate, however, it will be appreciated that the inlet and/or outlet ports need not be terminally positioned.
The channel 14 contains one or more pistons, such as pistons 24, 26, 28, 30. The pistons are preferably fluid impervious plugs disposed in the channel and sized for sealing engagement with the channel. In one embodiment, the pistons are formed of an elastomeric material, such as a fluoroelastomer (Viton®), butadienes such as polychloroprene (Neoprene®), silicone rubber, and the like. Preferably, the material from which the piston is formed is solvent resistant. In another embodiment, the pistons are a plug of, for example, an oil or a wax.
The device embodiment illustrated in FIG. 1A has four pistons in channel 14, where the pistons are in a spaced apart to define a volume between adjacent pistons. For example, a space 32 is defined by neighboring pistons 24, 26; space 34 is defined by neighboring pistons 26, 28; and space 36 is established by pistons 28, 30. Piston 24 has a first end 38 and a second end 40. Piston 26 has a first end 42 and a second end 44. Space 32 is defined by the gap between second end 40 of piston 24 and first end 42 of piston 26. It will be appreciated that as few as two pistons can be positioned in the channel, or considerably more pistons can be used, depending on the channel length and application. In one embodiment, a device comprising two pistons per channel is contemplated. In other embodiments, a device comprising three, preferably four, and still more preferably five, pistons per channel is contemplated.
Spaces or gaps 32, 34, 36, in various embodiments, contain a fluid, which intends a liquid or a gas. In a preferred embodiment, the fluid is a liquid. Spaces 32, 34, 36 can comprise the same or different fluids, depending on the application. In one embodiment, the fluid contained in the space between two neighboring pistons has a volume of in the range of between about 1-50 μL, more preferably of between about 1-30 μL, and still more preferably of between about 1-20 μL. In a preferred embodiment, a sample volume in the range of between about 1-5 μL is contained in a spaced between neighboring pistons, for introduction into a microfluidic device or for dispensing from the fluid handling device an amount of preferably at least about 70%, more preferably at least about 80%, still more preferably at least about 90% of the sample volume.
An exit port 48, shown in phantom in FIG. 1A, and visible in FIG. 1B, which shows the opposing side of device 10, provides communication with the interior of channel 14 and the external surroundings. Exit port 48 is disposed at any position along channel 14 between the inlet and outlet ports. In use, the pistons in the channel are moved from a first position to a second position, and in some embodiments to subsequent positions. For example, piston 24 is moved, typically in concert with the other pistons in the channel, past exit port 48. When second end 40 of piston 24 passes over exit port 48, fluid contained in space 32 flows through exit port 48. As seen in FIG. 1C, a microfluidic device 50 is aligned with device 10 to accept fluid contained in space 32 through an aperture in the microfluidic device (not visible). Alignment members 52, 54 can be provided to ensure that exit port 48 is correctly aligned with an aperture in the microfluidic device, for introduction of fluid from device 10 into, for example, a sample well or channel of microfluidic device 50. For example, device 50 includes a microfluidic channel 56.
It will be appreciated that the fluid handling device can be a unit separate and discrete from the microfluidic device, as illustrated in FIGS. 1A-1C, or can be integral with a microfluidic device. An device wherein the microfluidic channels, wells, reaction chambers, etc. are on the same substrate or on an integrally formed substrate with the channel(s) of the sample handling device is contemplated.
Conventional fluidic devices use circular or elongate read wells to contain fluid, e.g., for reading with an optical device. Unfortunately, due to the aspect change from small channels to large circular or elongate areas, air bubbles in the fluidic system tend to become entrapped, reduces the volume of the sample in the well and causing errors in the measurement of volume. In some embodiments, the microfluidic device 50 incorporates spiral read wells 57 to avoid the formation of air bubble in the wells. The spiral wells are first shown in FIG. 1C. FIGS. 1D and 1E shown an enlarged view of a spiral well 57 (FIG. 1E) compared to a conventional well 58, which tend to accumulate air bubbles 59 (FIG. 1D).
As mentioned above, pistons disposed in a channel are capable of movement from an initial position to one or more subsequent positions. In one embodiment, as a result of piston movement, one or more of the pistons serve as a valve, as illustrated in FIGS. 2A-2C. FIG. 2A shows a channel 60 containing pistons 62, 64. Pistons 62, 64 are in a spaced apart relationship to define a space 66 between neighboring piston ends, i.e., end 62a of piston 62 and end 64a of piston 64. An exit port 68 is disposed along the length of channel 60 to provide fluid communication between the channel interior and the environment exterior to the channel. Piston 62, in its first position, obstructs exit port 68, as seen in FIG. 2A. In this position, piston 62 acts as a valve in its “off” position. Applying force in the direction indicated by the arrow 70 causes the movement of pistons 62, 64, to a second position where piston 62 no longer obstructs exit port 68 (FIG. 2B). That is, piston 62 in its capacity as a valve has moved to its “on” position. In this position, fluid contained in space 66 can travel through exit port 66, in the direction indicated by arrow 72. Continued movement of the pistons in the direction of arrow 70 achieves movement of the pistons to a subsequent position, in this case to a third position, as illustrated in FIG. 2C. Piston 64 is positioned to obstruct exit port 68, i.e., the piston acts as a valve in an “off” position, so that fluid from the environment external to the channel does not enter the channel. Release of fluid contained in space 66 results in a reduction in the space defined by pistons ends 62a, 64a, as illustrated in FIG. 2C.
The pistons illustrated in FIGS. 2A-2C include a central portion having a smaller outer diameter than the piston ends. It will be appreciated that the shape of the pistons can vary and is not critical to the device described herein. A skilled artisan can envision alternative shapes that achieve the function of the pistons required for operation of the device.
In some embodiments, movement of the pistons in a channel requires greater force than expelling fluid out an exit port, and, e.g., into a channel of a microfluidic device. Thus, the force applied by an actuating member to move a first piston from a first position to a second position exceeds the force needed to expel fluid from between a first piston and a second piston. In this manner, in some embodiments, a first piston functions as a valve, moving from a first piston (i.e., an “off” position, where the piston obstructs fluid flow through an exit port), to an “on” position (i.e., where fluid flow through a port is permitted). Once the first piston is moved from its “off” position to its “on” position, subsequent force applied by an actuating member, causes fluid to flow out the exit port as a second, neighboring piston moves toward the first position, which remains substantially stationary in the channel. Only when fluid has flowed from the exit port and the second piston has contacted the first piston will the first piston again move in response to force applied to the actuating member.
With continuing reference to FIG. 1A, device 10, in some embodiments, can include a waste channel 80. Waste channel 80 as depicted in FIG. 1A is parallel to channel 14, however different orientations of the two channels is possible and is contemplated. Waste channel 80 has an inlet port 82 and an outlet port 84. Inlet port 82 is visible in the device orientation shown in FIG. 1B. When the device is mated and aligned with a microfluidic device, as shown in FIG. 1C, inlet port 82 is aligned to receive fluid from the microfluidic device.
In one embodiment, the waste channel is coated with or contains an absorbent material, to absorb or immobilize fluid waste in the waste channel. Absorbent materials are well known in the art and include moisture-wicking fabrics, dried hydrogels prepared from, for example, polyvinyl alchol, sodium polyacrylate, acrylate copolymers with hydrophilic moieties, cross-linked poly(ethylene oxides), polyvinylpyrrolidone, and others.
In another embodiment, the waste channel optionally includes one or more pistons. An exemplary embodiment is set forth in FIGS. 3A-3B. Channel 90 includes a piston 92 situated on one side of an inlet port 94. All or a portion of channel 90 can contain an absorbent material, such as material 96. In use and when inlet port 94 is in fluid-receiving alignment with an aperture in a microfluidic device, fluid is received into channel 90 via inlet port 94. The fluid is biased to flow into the region containing the absorbent material by the wicking action provided by the absorbent material. At a desired time, piston 92 can be moved from its initial position to a second position, as shown in FIG. 3B. In its second position, fluid entering the channel via inlet port 94 is blocked from flowing into the region containing the absorbent material, and is directed to a different channel region indicated in the figure as region 96. It will be appreciated that channel region 96 can optionally include a same or different absorbent material. A skilled artisan will recognized that this embodiment provides a means to separate fluids collected in the waste channel, to prevent undesired interactions, to permit identification of fluid collected in the waste channel, or other reasons.
In another embodiment, the device includes more than one channel and/or more than one waste channel. Returning to the device illustrated in FIG. 1A, the device is depicted with two channels, channel 14 and a channel 100, which extends between an inlet port 102 and an outlet port 104. Channel 100 contains one or more pistons, such as pistons 106, 108, 110, 112. The one or more pistons are in a spaced apart to define a space or gap between neighboring pistons, for retention of a fluid in the space. An exit port 114, visible in FIG. 1B, along channel 114 provides fluidic access between the channel interior and the exterior environment.
The device embodiment shown in FIGS. 1A-1C also includes a second waste channel 116, having features similar to that described for the first waste channel 80. In particular, waste channel 116 has an inlet port 118, for receiving a fluid from the environment exterior to the device, such as receipt of a fluid from a microfluidic device mated with the device, as shown in FIG. 1C. As with waste channel 80, channel 116 is shown in a parallel orientation with channel 100, however other orientations are possible.
As noted above, the pistons in each channel are slidably movable from a first position to one or more subsequent positions by an actuating element. An actuating element, or means for actuating, for moving the pistons along the channel can be a device as simple as a plunger inserted into the channel to the various embodiments of actuating elements set forth in FIGS. 4-7, now to be described.
In one embodiment, as shown in FIGS. 4A-4D, the actuating means is in the form of a ratcheting member. FIG. 4A shows a plurality of pistons 120, 122, 124, 126, 128, in a spaced-apart relationship to define a space between neighboring pistons for containing a fluid, indicated in the drawing as fluids 130, 132, 134, 136. A channel in which the series of pistons separated by regions of fluid resides is not shown in FIG. 4A to simplify viewing, however FIGS. 4C-4D illustrate a positional arrangement with a channel of a fluid handling device. Adjacent, and preferably in direct contact with, a terminal piston, such as piston 120, is a ratchet member 138. Ratchet member, best seen in FIG. 4B, includes a terminal portion 140 for abutment with, preferably, a terminal piston. A catch, or pawl, 142 is attached to the terminal portion of the ratchet member, by a flexible arm 144. A fluid handling device 146 has a series of teeth, such as teeth 148, 150, which define detentes (or notches), for engaging the ratchet member pawl 142, as seen best in FIG. 4D. Pawl 142 in FIG. 4C is positioned in the detente formed between teeth 148, 150. To advance the ratchet member, pawl 142 is pressed by the user to disengage the pawl from its detente between teeth 148, 150. A spring 152 may be employed to urge the ratchet member 138 in the direction of arrow 154. It will be appreciated that the spring can be positioned elsewhere in the device. It will also be appreciated that one or more edges or corners of pawl 142 and teeth, such as 148, 150, can be chamfered, such as chamfered edge 155 of tooth 156 to ease movement of the pawl between teeth.
Another embodiment of an actuating element is shown in FIGS. 5A-5D. A slide member 160 has a plurality of openings, such as opening 162. The number of openings typically corresponds to the number of channels in a particular fluid handling device (FIG. 5A). A solid region is positioned between neighboring openings, such as solid region 164 adjacent to opening 162. Slide member 160 is positioned in a fluid handling device, such as device 166, shown in partial view, wherein several channels in the device are illustrated (FIGS. 5B-5D).
FIGS. 5B-5D depict the device 166 in three stages of operation, where the position of slide member 160 and adjacent slide member 168 control the progression of s a piston 300 into the channel 301, by force of compressed springs 170. Each spring is at first held under tension, e.g., between solid region 164 and an equivalent solid region on adjacent slide member 168 (FIG. 5B).
When slide member 160 is moved to allow a spring 170 to pass through the opening 162, the piston 300 is forced into the channel 301 by an amount determined by the spring 170 (FIG. 5C). FIG. 5D shows the next stage of operation, when adjacent slide member 168 is moved in a similar manner, forcing the piston 300 into the channel 301 by another defined amount or increment.
It will be appreciated that one or more slide members and springs can be arranged to permit successive advancement of pistons aligned in a channel.
FIGS. 6A-6D illustrate yet another embodiment of an actuating element, to achieve movement of a piston 300 into a channel 301 of the fluid handling device 166. In this embodiment, rotating bar 180 has a series of openings, such as opening 182, separated by solid regions, such as region 184 (FIG. 6A). The bar is adapted to fit in a fluid handling device 186, shown in partial view in FIGS. 6B-6D.
FIGS. 6B-6D depict the device 186 in three stages of operation, where the position of rotating bar 180 and adjacent rotating bar 185 (shown in side view) control the progression of piston 300 into the channel 301, by force of compressed springs 170. Each spring is at first held under tension, e.g., between solid region 184 and an equivalent solid region on adjacent rotating bar 185 (FIG. 5B).
When rotating bar 180 is rotated to allow a spring 170 to pass through the opening 182, the piston 300 is forced into the channel 301 by an amount determined by the spring 170 (FIG. 6C). FIG. 6D shows the next stage of operation, when adjacent rotating bar 185 is moved in a similar manner, forcing the piston 300 into the channel 301 by another defined amount or increment.
It will be appreciated that one or more rotating bars and springs can be arranged to permit successive advancement of pistons aligned in a channel.
FIGS. 7A-7D show another embodiment of an actuating element, where the actuating element is formed of a material that responds to heat, typically by entering a physically weakened condition as in becoming more fluid or melting. In this embodiment, a fuse member 200 in the form of an elongate strip of a heat-responsive material is used (FIG. 7A). The fuse member 200 is adapted to fit in a fluid handling device 202, shown in partial view in FIGS. 7B-7D.
FIGS. 7B-7D depict the device 202 in three stages of operation, where a first fuse member 200 and adjacent fuse member 204 control the progression of piston 300 into the channel 301, by force of compressed springs 170. Each spring is at first held under tension, e.g., between the fuse members 200, 204 (FIG. 7B).
When the first fuse member 200 is melted, e.g., by application of heat, spring 170 passes through the melted remains of fuse member 200, and the piston 300 is forced into the channel 301 by an amount determined by the spring 170 (FIG. 7C). FIG. 7D shows the next stage of operation, when adjacent fuse member 204 is melted in a similar manner, forcing the piston 300 into the channel 301 by another defined amount or increment.
It will be appreciated that one or more fuse members and springs can be arranged to permit successive advancement of pistons aligned in a channel.
FIG. 8 shows a fluid handling device 220 having a series of parallel channels, such as channels 222, 224. Channel 222 is connected to channel 224 by channel 223. Channel 222 comprises a plurality of pistons, 226, 228, 230, 232, 234. Channel 224 comprises two pistons, 236, 238. Piston 238 is initially positioned to block channel 223 (as in a valve in the “off” position), but is movable in the direction of arrow 240 such that fluid contained in the space between pistons 236, 238 flows into channel 223. The fluid flows into channel 222 and enters the space between neighboring pistons 234, 232 residing in channel 222. The fluid mixes with a solid or liquid reagent in the space between pistons 234, 232. Activation of the actuating element 242 advances the pistons in channel 222, dispensing sequentially the fluid between neighboring pistons 234 and 232; 232 and 230; 230 and 228; and 228 and 226.
FIGS. 9A-9B show a piston 242 with a central bore or “through-hole” 244 (visible only in FIG. 9B). Piston 242 is one of a plurality of pistons arranged for insertion, or already inserted into, a channel of a fluid handling device. In this embodiment, piston 242 is disposed between a terminal piston 246 and a neighboring piston 248. A space 250 is defined between the terminal piston 246 and piston 242 for containing a first fluid. A second space 252 is defined between piston 242 and neighboring piston 248 for containing a second fluid. Activation of actuating element 254 to advance the pistons results in movement of the first fluid in space 250 into through-hole 244 for contact, and mixing, with the second fluid in space 252. At the same time, the remaining pistons are advanced, and fluid is introduced into a mated microfluidic device. Subsequent movement of the actuating element further advances one or more of the pistons, for introduction of fluid contained between the neighboring pistons into the microfluidic device. It will be appreciated that a piston with a through-hole or central bore may include a valve or plug to prevent fluid from moving through the bore until such movement is desired. The central bore of the piston can be adapted with, for example, a one-way check valve or with a plug of oil or wax at one end of the bore. It will also be appreciated that the system can also be arranged such that all the pistons have a central hole with a valve and a liquid held in between at least two pistons. The liquid is induced to move in to the exit channel by opening the first piston's valve and pushing the series of pistons and liquid forward. The next piston can open its valve upon contact with the first by a mechanical or other means to release the liquid behind it to enter into the central bore of the pistons and into the exit channel. This arrangement can be repeated as many times as desired.
An alternative embodiment of a fluid handling device is illustrated in FIGS. 10A-10C. Device 260 is comprised of a conventional syringe, comprised of a cylindrical barrel 262 and a plunger 264. The barrel has an end with a large opening for receiving plunger 264 and an end with a small opening for communicating with a needle 272. Plunger 264 is moveable in a sliding, fluid-sealing arrangement within barrel 262. One end of plunger 264 is comprised of two or more pistons, such as pistons 266, 268. A space 270 exits between adjacent ends of neighboring pistons 266, 268. A needle 272 extends from a skin piercing distal tip 274 to a proximal end 276 fixed in any one of various known manners to device 260. Needle 272 extends through the pistons, as seen best in FIG. 10B. Needle 272 includes an fluid port 278, visible in FIG. 10C. In preferred embodiments, the needle 272 is positioned such that the fluid port 278 is near the end of the cylindrical barrel 262 that has the small opening. Movement of plunger 264 advances the pistons over needle 272. As the fluid contained in the spaces between neighboring pistons moves over fluid port 278, the fluid enters the port and is dispensed through an opening in tip 274. It will be appreciated that tip 274 can be inserted through the skin or other tissue of a subject, or can be inserted into an aperture of a device.
The fluid handling device described herein can be fabricated from a variety of materials, and selection of a suitable material is within the knowledge of a skilled artisan. Exemplary materials include metals and plastics, including but not limited to rigid elastomers, synthetic and natural rubber, glass, quartz, silicone rubber, and the like.
While a number of exemplary aspects and embodiments have been discussed above, those of skill in the art will recognize certain modifications, permutations, additions and sub-combinations thereof. It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions and sub-combinations as are within their true spirit and scope.
Patent Application
20080089799
