Micro-feature devices can be used for performing multiplexed experiments on cell cultures. Very small features sizes for such devices can be required to successfully maintain cell cultures. However, it can be difficult to reliably form devices with features sizes that are sufficiently small. Traditional techniques for forming such devices can be time consuming and expensive.
The systems, methods, and devices of the disclosure each have several innovative aspects, no single one of which is solely responsible for the desirable attributes disclosed herein.
One innovative aspect of the subject matter described in this disclosure can be implemented in a micro-feature device. The micro-feature device can include a substantially rigid transparent substrate. The device can include a plurality of macrowells defined in the transparent substrate. Each macrowell can have a width in the range of about one millimeter to about 35 millimeters and a depth in the range of about two millimeters to about 12 millimeters. Each macrowell can include a respective plurality of microwells defined in a respective lower surface of the macrowell. Each microwell can have a width in the range of about 50 microns to about 500 microns and a depth in the range of about 50 microns to about 500 microns.
In some implementations, each pair of adjacent macrowells can be separated by a distance in the range of about 0.5 millimeters to about five millimeters. In some implementations, each macrowell can have a height-to-width ratio in the range of about 1:1 to about 5:1. In some implementations, each pair of adjacent microwells can be separated by a distance in the range of about 50 microns to about 200 microns. In some implementations, each microwell can have a height-to-width ratio in the range of about 1:1 to about 5:1.
In some implementations, the transparent substrate can include at least one of polystyrene, polycarbonate, polymethylpentene, a cyclic olefin copolymer, and polydimethylsiloxane (PDMS). In some implementations, a distance between a lower surface of the transparent substrate and a lower surface of at least one microwell of the plurality of microwells can be between about 25 microns and about 200 microns. In some implementations, a distance between a lower surface of the transparent substrate and a lower surface of each microwell of the plurality of microwells can be substantially uniform.
In some implementations, a bottom surface of each microwell can include a layer of polymer material. In some implementations, the layer of polymer material at the bottom of each microwell can have a thickness in the range of about 0.5 microns to about 25 microns. In some implementations, the layer of polymer material can include at least one of polyurethane and epoxy. In some implementations, the layer of polymer material can include silicone, such as PDMS.
Another innovative aspect of the subject matter described in this disclosure can be implemented in a method of fabricating a micro-feature device. The method can include positioning an outer mold in contact with at least two opposing side surfaces and a portion of an upper surface of a substantially rigid transparent substrate. A coefficient of thermal expansion of the outer mold can be less than a coefficient of thermal expansion of the transparent substrate. The method can include positioning an inner mold on the upper surface of the transparent substrate. The coefficient of thermal expansion of the transparent substrate can be less than a coefficient of thermal expansion of the inner mold. The method can include applying a first platen at a first temperature to the inner mold to cause the inner mold to form a plurality of macrowells defined in the transparent substrate, and a respective plurality of microwells defined in a respective lower surface of each macrowell. Each macrowell can have a width in the range of about one millimeter to about 35 millimeters and a depth in the range of about two millimeters to about 12 millimeters. Each microwell can have a width in the range of about 50 microns to about 500 microns and a depth in the range of about 50 microns to about 500 microns. The method can include cooling the outer mold, the transparent substrate, and the inner mold to a second temperature, lower than the first temperature. The method can include removing the inner mold from the transparent substrate. The method can include removing the transparent substrate from the outer mold.
In some implementations, the method can include selecting a first material for the inner mold. The first material can be selected to be softer than the transparent substrate. The first material can have a durometer measurement in the range of about 30A to about 80A. In some implementations, the method can include selecting a second material for the outer mold. The second material can be selected to be harder than the transparent substrate. The second material can have a Mohs hardness in the range of about 2 to about 3 or a Rockwell hardness in the range of about R120 to about R130. In some implementations, the inner mold is formed from polydimethylsiloxane (PDMS).
In some implementations, the inner mold can include a plurality of macropillars extending outward from a surface of the inner mold. Each macropillar can include a respective plurality of micropillars extending outwards from a respective surface of the macropillar. In some implementations, each macropillar can have a width in the range of about one millimeter to about 35 millimeters and a height in the range of about two millimeters to about 12 millimeters. In some implementations, each pair of adjacent macropillars can be separated by a distance in the range of about 0.5 millimeters to about five millimeters. In some implementations, each macropillar can have a height-to-width ratio in the range of about 1:1 to about 5:1. In some implementations, each micropillar can have a width in the range of about 50 microns to about 500 microns and a height in the range of about 50 microns to about 500 microns. In some implementations, each pair of adjacent micropillars can be separated by a distance in the range of about 25 microns to about 200 microns. In some implementations, each micropillar can have a height-to-width ratio in the range of about 1:1 to about 5:1.
In some implementations, the inner mold can include a material that is permeable to gas. In some implementations, the transparent substrate can be formed from at least one of polystyrene, polycarbonate, polymethylpentene, and a cyclic olefin copolymer.
In some implementations, the method can include providing a supporting platform in contact with a lower surface of the transparent substrate and applying a second platen at a second temperature to the supporting platform. In some implementations, the method can include providing a supporting platform including a thermal buffer layer in contact with a lower surface of the transparent substrate and applying a second platen at an ambient temperature to the supporting platform. In some implementations, the thermal buffer layer can be formed from one of polyether ether ketone (PEEK) or a polyimide film.
In some implementations, the thermal buffer layer can be formed from one of polyether ether ketone (PEEK) or a polyimide film. In some implementations, the method can include depositing a coating comprising a polymer material on a bottom surface of each microwell. In some implementations, the coating can include at least one of polyurethane and epoxy. In some implementations, the coating can include silicone, such as PDMS. In some implementations, the coating also can include a solvent. In some implementations, the coating can be a conformal coating applied over the bottom surface and sidewalls of each microwell. In some implementations, the coating can have a thickness in the range of about 0.5 microns to about 25 microns.
Another innovative aspect of the subject matter described in this disclosure can be implemented in a method of fabricating a micro-feature device. The method can include positioning an outer mold in contact with at least two opposing side surfaces and a portion of an upper surface of a substantially rigid transparent substrate. A coefficient of thermal expansion of the outer mold can be less than a coefficient of thermal expansion of the transparent substrate. The method can include positioning a first inner mold on the upper surface of the transparent substrate. The coefficient of thermal expansion of the transparent substrate can be less than a coefficient of thermal expansion of the first inner mold. The method can include applying a first platen at a first temperature to the first inner mold to cause the first inner mold to form a plurality of macrowells defined in the transparent substrate. Each macrowell can have a width in the range of about one millimeter to about 35 millimeters and a depth in the range of about two millimeters to about 12 millimeters. The method can include cooling the outer mold, the transparent substrate, and the first inner mold to a second temperature, lower than the first temperature. The method can include removing the first inner mold from the transparent substrate. The method can include depositing a layer of polymer material onto a bottom surface of each macrowell. The method can include positioning a second inner mold on an upper surface of the layer of polymer material to cause the second inner mold to form a respective plurality of microwells defined in a respective lower surface of each macrowell. Each microwell can have a width in the range of about 50 microns to about 500 microns and a depth in the range of about 50 microns to about 500 microns. The method can include curing the layer of polymer material.
In some implementations, the layer of polymer material at the bottom of each microwell can have a thickness in the range of about 0.5 microns to about 25 microns. In some implementations, the second inner mold can include at least one of polyurethane and epoxy. In some implementations, the second inner mold can include an elastomer, such as PDMS or fluorinated PDMS. In some implementations, the second inner mold can include a material that is permeable to gas. In some implementations, the layer of polymer material can include at least one of polyurethane and epoxy. In some implementations, the layer of polymer material can include silicone, such as PDMS.
The skilled artisan will understand that the figures, described herein, are for illustration purposes only. It is to be understood that in some instances various aspects of the described implementations may be shown exaggerated or enlarged to facilitate an understanding of the described implementations. In the drawings, like reference characters generally refer to like features, functionally similar elements, and/or structurally similar elements throughout the various drawings. The drawings are not necessarily to scale. Instead, emphasis is placed upon illustrating the principles of the teachings. The drawings are not intended to limit the scope of the present teachings in any way. The system and method may be better understood from the following illustrative description with reference to the following drawings in which:
Like reference numbers and designations in the various drawings indicate like elements.
The various concepts introduced above and discussed in greater detail below may be implemented in any of numerous ways, as the described concepts are not limited to any particular manner of implementation. Examples of specific implementations and applications are provided primarily for illustrative purposes.
The systems and methods disclosed are generally related to a micro-feature device. More particularly, the systems and methods enable fabrication of a device that can be used to culture cells for high-throughput screening. In some implementations, the device is used to model how human organ systems respond to agents such as toxins or medications. In some implementations, the cell cultures can be imaged using a high resolution microscope at high magnification, such as 100×.
Each macrowell 104 has a substantially square cross-sectional shape and is defined by four sidewalls and a bottom. In some other implementations, the macrowells 104 can have other cross-sectional shapes. For example, the macrowells 104 can have polygonal cross-sectional shapes, such as triangular, rectangular, or hexagonal cross-sectional shapes. In some other implementations, the macrowells 104 can have circular cross-sectional shapes. In still other implementations, the macrowells 104 can have polygonal cross-sectional shapes with rounded corners. The top of each macrowell 104 remains open.
In some implementations, the micro-feature device 100 can serve as a model for an organ, for example by allowing cells to be cultured within each microwell 106. In some implementations, the small enclosed space defined by each microwell 106 can provide a favorable environment in which to culture human hepatocytes. Thus, the micro-feature device 100 can serve as a model for the human liver. In some implementations, hepatocytes can be cultured in the microwells 106 for relatively long time periods. For example, primary hepatocyte characteristics can be maintained within the microwells 106 over a period of at least about three weeks to about five weeks. This can allow the micro-feature device 100 to be used to test the efficacy of drugs on diseases that impact liver cells, such as malaria, over a relatively long period of time.
In some implementations, the arrangement of macrowells 104 and microwells 106 in the micro-feature device 100 can facilitate high-throughput screening of drugs in a laboratory setting. For example, each microwell 106 defines an enclosed space that can contain a respective cell culture, but also remains open on top. Likewise, the macrowells 104 in which the microwells 106 are defined also remain open on top. Thus, cell samples can be easily introduced into the microwells for culturing, for example via pipettes. In some implementations, reagents such as nutrients, toxins, drugs, or other biologically active materials can be introduced into all of the microwells 106 of a single macrowell 104 substantially simultaneously, due to the arrangement of microwells 106 within the macrowells 104. For example, the microwells 106 each have substantially the same dimensions and are distributed substantially uniformly over the entire bottom surface of each macrowell 104. Thus, large reagent samples can be introduced into a macrowell 104 and an approximately equal portion of the reagent can flow into each microwell 106. The arrangement of the macrowells 104 also can facilitate high-throughput screening. For example, the grid pattern of macrowells 104 can easily interface with standard microtiter equipment, such as robotic pipetters and imaging equipment.
The microwells 106 have a width W3, and each microwell is separated from an adjacent microwell by a sidewall 109 having a width W4. In some implementations, the width W3 of the microwells 106 can be in the range of about 50 microns to about 500 microns. For example, the width W3 of the microwells 106 can be about 50 microns, about 100 microns, about 200 microns, about 300 microns, about 400 microns, or about 500 microns. In some implementations, the height of the microwells 106 can be in the range of about 50 microns to about 500 microns. For example, the height of the microwells 106 can be about 50 microns, about 100 microns, about 200 microns, about 300 microns, about 400 microns, or about 500 microns. In some implementations, the height-to-width ratio for the microwells 106 can be in the range of about 1:1 to about 5:1. For example, the height-to-width ratio for the microwells 106 can be about 1:1, about 2:1, about 3:1, about 4:1, or about 5:1. In some other implementations, the height-to-width ratio for the microwells 106 can be less than 1:1.
The micro-feature device 100 has a thickness H2 between the bottom surface of the micro-feature device 100 and the bottom surface of each microwell 106. In some implementations, the micro-feature device 100 can be used to image respective cell cultures within the microwells 106. Therefore, the material used to form the micro-feature device can be selected to be optically clear, so that cell cultures can be imaged by equipment positioned outside of the micro-feature device 100. For example, high resolution microscopes can be used to view cell cultures through the bottom surface of the micro-feature device 100. Thus the thickness H2 between the bottom surface of the micro-feature device 100 and the bottom surface of each microwell 106 can be selected to facilitate high resolution microscopy (e.g., 100× magnification). In some implementations, microscope objectives may have very short focal lengths, and therefore the thickness H2 should be relatively small in order to position a microscope outside the micro-feature device 100 within a desired focal length of the bottom of each microwell 106. In some implementations, the thickness H2 can be in the range of about 25 microns to about 200 microns. In addition, to facilitate accurate imaging of cells in all of the microwells 106 of the micro-feature device 100, the thickness H2 can be substantially uniform across the entire micro-feature device 100.
Referring now to
The material used to form the outer mold 300 also can be selected to have a relatively low coefficient of thermal expansion, so that the outer mold 300 will not expand significantly when subjected to high temperatures. In some implementations, the material used to form the outer mold 300 can have a coefficient of thermal expansion in the range of about 12 (10−6 m/(m K)) to about 56 (10−6 m/(m K)). For example, in some implementations, the material used to form the outer mold 300 can have a coefficient of thermal expansion of about 12 (10−6 m/(m K)), about 22.2 (10−6 m/(m K)), or about 55.8 (10−6 m/(m K)). In some implementations, the material for the outer mold 300 is selected to have a coefficient of thermal expansion that is lower than the coefficient of thermal expansion of a substrate that is to be formed into the micro-feature device through a molding process. This can facilitate removing the manufactured micro-feature device from the outer mold at the end of the molding process, as discussed further below in connection with the process 200 shown in
The material used to form the outer mold 300 also can be selected to have a high thermal conductivity, so that heat from a platen applied to the outer mold 300 can be efficiently transferred to the substrate. In some implementations, the outer mold 300 is formed from a relatively rigid material. For example, the outer mold 300 can be formed from a metal, such as aluminum. In other implementations, the outer mold 300 can be formed from a metal alloy. Metals can be well suited for use in the outer mold 300, because many metals have relatively low coefficients of thermal expansion, relatively high thermal conductivities, and also are structurally rigid. However, in some other implementations, the outer mold 300 can be formed from a semiconducting material such as silicon, or a rigid plastic material such as polyetherimide (PEI) or polysulfone, provided that the selected material has a suitable low coefficient of thermal expansion and a suitably high thermal conductivity. In implementations in which the outer mold 300 is formed from a metal or metal alloy, the outer mold can have a Mohs hardness in the range of about 2 to about 3. In implementations in which the outer mold 300 is formed from a polymer, the outer mold can have a Rockwell hardness in the range of about R120 to about R130.
In some implementations, the recess 302 and the cutout 304 can be formed in the outer mold 304 using conventional machining techniques. The size and shape of the recess 302 of the outer mold 300 can be selected based on the size and shape of the substrate that is to be molded to form the micro-feature device. Thus, the height of the sidewalls of the recess 302 can be selected to be approximately equal to the thickness of the substrate. In some implementations, the substrate (and therefore the sidewalls of the recess 302) can have a thickness in the range of about 1 millimeter to about 5 millimeters. For example, the substrate can have a thickness of about 1 millimeter, about 2 millimeters, about 3 millimeters, about 4 millimeters, or about 5 millimeters. As discussed above, the bottom surface of the outer mold 300 is shown facing up in
As described further below, the inner mold 330 can be pressed into a substrate in order to mold the substrate into the shape of the micro-feature device 100 shown in
Similar to the macrowells discussed above, the width of the macropillars 334 can be in the range of about one millimeter to about 35 millimeters. For example, the width of the macropillars 334 can be about one millimeter, about two millimeters, about three millimeters, about four millimeters, about five millimeters, about 10 millimeters, about 15 millimeters, about 20 millimeters, about 25 millimeters, or about 30 millimeters. In some implementations, the height of the macropillars 334 can be in the range of about two millimeters to about 12 millimeters. For example, the width of the macropillars 334 can be about two millimeter, about three millimeters, about four millimeters, about five millimeters, about 8 millimeters, about 10 millimeters, or about 12 millimeters. In some implementations, the height-to-width ratio for the macropillars 334 can be in the range of about 1:1 to about 5:1. For example, the height-to-width ratio for the macropillars 334 can be about 1:1, about 2:1, about 3:1, about 4:1, about 5:2, or about 5:1. In some other implementations, the height-to-width ratio for the macropillars 334 can be less than 1:1. For example, the height-to-width ratio for the macropillars 334 can be about 3:5. The macropillars 334 can be separated by a distance in the range of about 0.5 millimeters to about five millimeters. For example, the macropillars 334 can be separated by a distance of about one millimeter, about two millimeters, about three millimeters, about four millimeters, or about five millimeters.
Similarly, the arrangement of the micropillars 336 on the surface of the macropillar 334a can be the same as the arrangement of the microwells within a macrowell. For example, in some implementations the macropillar 334a can include between 10 and 50 micropillars 336, between 50 and 100 micropillars 336, between 100 and 150 micropillars 336, between 150 and 200 micropillars 336, between 200 and 250 micropillars 336, between 250 and 300 micropillars 336, between 300 and 350 micropillars 336, or between 350 and 400 micropillars 336. In some implementations, the macropillar 334a can include more than 400 micropillars 336. The arrangement of the micropillars 336 on the surface of the macropillar 334a can be selected based on the shape of the macropillar 334a. For example, as shown in
In some implementations, the width of the micropillars 336 can be in the range of about 50 microns to about 500 microns. For example, the width of the micropillars 336 can be about 50 microns, about 100 microns, about 200 microns, about 300 microns, about 400 microns, or about 500 microns. In some implementations, the height of the micropillars 336 can be in the range of about 50 microns to about 500 microns. For example, the height of the micropillars 336 can be about 50 microns, about 100 microns, about 200 microns, about 300 microns, about 400 microns, or about 500 microns. In some implementations, the height-to-width ratio for the micropillars 336 can be in the range of about 1:1 to about 5:1. For example, the height-to-width ratio for the micropillars 336 can be about 1:1, about 2:1, about 3:1, about 4:1, or about 5:1. In some other implementations, the height-to-width ratio for the micropillars 336 can be less than 1:1.
In some implementations, the inner mold 330 is formed from a relatively soft material. For example, the material used to form the inner mold 330 can have a durometer measurement in the range of about 30A to about 80A. In some implementations, the material used to form the inner mold 330 can have a durometer measurement of about 50A. In some implementations, the soft material is a polymer. For example, the inner mold 330 can be formed from polydimethylsiloxane (PDMS). In some other implementations, the inner mold 330 can be formed from a soft silicone or a rubber material. In some other implementations, the inner mold 330 can be formed from two materials. For example, the inner mold 330 can include a relatively rigid material forming a relatively thin layer including the macropillars 334 and the micropillars 336, and a relatively soft material forming the rest of the inner mold 330. In some other implementations, the inner mold 330 can include a relatively soft material including the macropillars 334 and the micropillars 336, and a relatively rigid material forming the rest of the inner mold 330. The relatively rigid material forming the rest of the inner mold 330 could also be used to form supporting structures inside the macropillars.
The material used to form the inner mold 330 also can be selected to have a relatively high coefficient of thermal expansion, so that the inner mold will tend to contract significantly after being cooled from a high temperature to room temperature. In some implementations, the material for the inner mold 330 can be selected to have relatively high gas permeability, and to have a coefficient of thermal expansion that is higher than the coefficient of thermal expansion of the substrate that is to be formed into the micro-feature device. This can help to avoid bubble-like defects in the manufactured micro-feature device and can facilitate removing the inner mold 330 from the manufactured micro-feature device, as discussed further below in connection with the process 200 shown in
In some implementations, the inner mold 330 can be fabricated using a rigid master mold. For example, in some implementations, a mold made from a rigid material may be more durable and longer lasting than one made from a soft material. However, rigid materials typically do not have the high coefficients of thermal expansion and flexibility that are desirable for the inner mold 330. Moreover, a rigid mold may take longer to fabricate than a soft mold, increasing the required turnaround time for prototyping. As a result, an approach that combines durability of rigid molds with the rapid fabrication and ease of de-molding of soft molds, can be advantageous. Thus, a rigid master mold can be fabricated with small features corresponding to the micropillars 336. Such small features can be formed in a rigid master mold using various techniques, such as micromachining or lithography, which may not be suitable for defining features in the softer material to be used as the inner mold. The shape of the rigid master mold can then be transferred to the inner mold, for example by injection or replica molding. In some implementations, the master mold can be formed from silicon or a metal such as aluminum or nickel.
As shown in both
The process 200 includes positioning an inner mold on an upper surface of the transparent substrate (stage 204).
The process 200 includes applying a first platen at a first temperature to the inner mold 330 to form a plurality of macrowells and microwells defined in the transparent substrate 450 (stage 206).
In the first implementation of the process 200, shown in
In the first implementation of the process 200, shown in
In the second implementation of the process 200, shown in
The first platen 460 can be pressed downwards against the substrate 450. In some implementations, the first platen 460 can exert a pressure in the range of about 30 PSI to about 70 PSI on the first substrate. As a result of the pressure and temperature applied to the substrate 460, the inner mold 330 is compressed slightly and the viscosity of the substrate 450 is reduced, allowing the inner mold 330 to pass through the upper surface of the substrate 450. As the material of the substrate 450 is displaced by the inner mold 330, the level of the upper surface of the substrate 450 rises.
In some implementations, air may become trapped at the interface of the inner mold 330 and the substrate 450. Trapped air can result in bubble-like defects in the surface of the finished micro-feature device. In order to prevent air from becoming trapped, the inner mold 330 can be formed from a material that is permeable to gas so that air can pass through the inner mold 330 without becoming trapped in the substrate 450. In some implementations, a gas permeable material such as PDMS can be used to form the inner mold 330.
As discussed above, it can be desirable to fabricate a micro-feature device having a thickness that is substantially uniform across the entire bottom surface to allow microscopes to accurately image cell cultures within the device. Using the thermal buffer platform 470 as shown in
The process 200 includes cooling the outer mold 300 and the inner mold 330 to a second temperature (stage 208).
The process 200 includes removing the inner mold from the transparent substrate (stage 210).
The process 200 includes removing the transparent substrate from the outer mold (stage 212). The resulting micro-feature device 100 is shown in
In some implementations, the process 200 also can include applying a coating to the microwells 106 of the device 100. The material used to coat the microwells 106 can be selected, for example, to be compatible with the cells that are to be cultured in the microwells 106. In some implementations, the coating can be a polymer material, such as silicone, polyuerathane, or epoxy. In some implementations, the polymer material can be PDMS.
As shown in
In some implementations, the material forming the coating 490 can be applied a liquid. For example, the coating 490 can be applied by spray coating a liquid material, such as liquid PDMS. In some implementations, a solvent or other thinning agent may be added to the material that will form the coating 490. For example, the solvent can thin the material, thereby facilitating the formation of a thin conformal coating 490. In some implementations, the coating 490 can be applied by ink jet printing a layer of material over the microwells 106. In still other implementations, a different precision deposition process may be used. The coating 490 can then be cured to solidify the material forming the coating 490. In some implementations, the microwells 106 may be preheated prior to the deposition of the coating 490 such that at least a portion of the coating 490 begins to cure upon contact with the microwells 106. In some other implementations employing other coatings, the coating 490 may be cured by other means, such as the application of UV light.
Referring again to
The process 700 includes positioning a first inner mold on an upper surface of the transparent substrate (stage 704).
The process 700 includes applying a first platen at a first temperature to the first inner mold 830 to form a plurality of macrowells defined in the transparent substrate 850 (stage 706).
In some implementations, the first platen 860 can be controlled to between about 400 degrees Fahrenheit and about 510 degrees Fahrenheit. The temperature of the first platen 860 can be selected based on the material of the substrate 850. For example, if the substrate 850 is made from polystyrene, the first platen 860 can be controlled to be about 411 degrees. If the substrate 850 is made from polycarbonate, the first platen 860 can be controlled to be about 492 degrees. If the substrate 850 is made from polymethylpentene, the first platen 460 can be controlled to be about 469 degrees. If the substrate 850 is made from a cyclic olefin polymer such as Zeonor, the first platen 860 can be controlled to be about 479 degrees. If the substrate 850 is made from a cyclic olefin polymer such as Topas, the first platen 860 can be controlled to be about 501 degrees.
The second platen 865 can be controlled to between about 300 degrees Fahrenheit and about 410 degrees Fahrenheit. The temperature of the second platen 865 also can be selected based on the material of the substrate 850. For example, if the substrate 850 is made from polystyrene, the second platen 865 can be controlled to be about 310 degrees. If the substrate 850 is made from polycarbonate, the second platen 865 can be controlled to be about 391 degrees. If the substrate 850 is made from polymethylpentene, the second platen 865 can be controlled to be about 368 degrees. If the substrate 850 is made from a cyclic olefin polymer such as Zeonor, the second platen 865 can be controlled to be about 378 degrees. If the substrate 850 is made from a cyclic olefin polymer such as Topas, the second platen 865 can be controlled to be about 400 degrees.
The first platen 860 can be pressed downwards against the substrate 850. In some implementations, the first platen 860 can exert a pressure in the range of about 30 PSI to about 70 PSI on the first substrate. As a result of the pressure and temperature applied to the substrate 860, the inner mold 830 is compressed slightly and the viscosity of the substrate 850 is reduced, allowing the inner mold 830 to pass through the upper surface of the substrate 850. As the material of the substrate 850 is displaced by the inner mold 830, the level of the upper surface of the substrate 850 rises.
In some implementations, air may become trapped at the interface of the first inner mold 830 and the substrate 850. Trapped air can result in bubble-like defects in the surface of the finished micro-feature device. In order to prevent air from becoming trapped, the inner mold 830 can be formed from a material that is permeable to gas so that air can pass through the inner mold 830 without becoming trapped in the substrate 850. In some implementations, a gas permeable material such as PDMS can be used to form the inner mold 830.
The process 700 includes cooling the outer mold 300 and the inner mold 330 to a second temperature (stage 708).
The process 700 includes removing the first inner mold from the transparent substrate (stage 710).
The process 700 includes depositing a layer of polymer material onto a bottom surface of each macrowell (stage 712).
The process 700 includes positioning a second inner mold on an upper surface of the layer of polymer material to cause the second inner mold to form a respective plurality of microwells defined in a respective lower surface of each macrowell (stage 714).
In some implementations, the second inner mold 875 can also be formed from a polymer material, such as PDMS. In implementations in which both the second inner mold 875 and the deposited layer of polymer material 870 are formed from PDMS, the second inner mold 875 can be treated to prevent adhesion of the layer of polymer material 870 to the PDMS forming the second inner mold 875. For example, the surface of the second inner mold 875 can be fluorinated to prevent adhesion. In other implementations, the second inner mold 875 can be formed from a different material, such as polyurethane, epoxy, or other elastomers. To prevent the formation of air bubbles in the layer of polymer material 870, the second inner mold 875 also can be formed from a material that is permeable to gas, as discussed in greater detail above. The second inner mold 875 can be pressed into the layer of polymer material 870. As the layer of polymer material 870 is displaced by the second inner mold 875, the level of the upper surface of the layer of polymer material 870 rises. The voids created by the micropillars of the second inner mold 875 within the layer of polymer material 870 define the microwells of the micro-feature device, as shown in
The process 700 includes curing the layer of polymer material (stage 716). In some implementations, the layer of polymer material 870 can be cured while the second inner mold 875 is still pressed into the layer of polymer material 870, so that the layer of polymer material 870 can retain its shape during the curing process. The curing process can solidify the layer of polymer material 870 and bond the layer of polymer material 870 to the underlying substrate 850. In some implementations, the layer of polymer material 1870 can be cured by exposing the layer of polymer material to heat and pressure. In other implementations, the layer of polymer material 870 can be cured in other ways. For example, the layer of polymer material 870 can be treated with a photosensitive material and exposed to ultraviolet light to cure the layer of polymer material 870.
The process 700 can include removing the platform 823, the outer mold 300, and the second inner mold 875. The resulting micro-feature device 895 is shown in
Various modifications to the implementations described in this disclosure may be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other implementations without departing from the spirit or scope of this disclosure. Thus, the claims are not intended to be limited to the implementations shown herein, but are to be accorded the widest scope consistent with this disclosure, the principles and the novel features disclosed herein.
Certain features that are described in this specification in the context of separate implementations also can be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation also can be implemented in multiple implementations separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.
Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Further, the drawings may schematically depict one more example processes in the form of a flow diagram. However, other operations that are not depicted can be incorporated in the example processes that are schematically illustrated. For example, one or more additional operations can be performed before, after, simultaneously, or between any of the illustrated operations. In certain circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations. Additionally, other implementations are within the scope of the following claims. In some cases, the actions recited in the claims can be performed in a different order and still achieve desirable results.
The present application for claims priority to U.S. Provisional Application No. 62/013,854, entitled “Multiplexed Liver Model for High-Throughput Drug Screening,” filed Jun. 18, 2014; U.S. Provisional Application No. 62/086,012, entitled “Multiplexed Liver Platform for High-Throughput Screening,” filed Dec. 1, 2014; and U.S. Provisional Application No. 62/151,292, entitled “Design And Hot Embossing Of Macro And Micro Features With High Resolution Microscopy Access,” filed Apr. 22, 2015, all of which are assigned to the assignee hereof and hereby expressly incorporated by reference herein.
Number | Date | Country | |
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62013854 | Jun 2014 | US | |
62086012 | Dec 2014 | US | |
62151292 | Apr 2015 | US |