Systems and methods for manufacturing enclosed microfluidic devices - Patents.com

Abstract

A method for manufacturing a microfluidic device can include providing a base component for defining a first portion of the microfluidic device. A cap component of the microfluidic device can be fabricated having a sealing lip extending a first distance from a first side of the cap component and a support portion extending a second distance from the first side of the cap component that is less than the first distance. The method can include placing the cap component and the base component in a mold such that the sealing lip of the cap component contacts the base component. The base component, the support portion of the cap component, and the sealing lip of the cap component can together define a cavity. The method can include injecting a polymer material into the mold to fill the cavity with the polymer material. TIFF2022549297000002.tif128128

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application No. 62 / 905,665, entitled "SYSTEMS AND METHODS FOR MANUFACTURING CLOSED MICROFLUIDIC DEVICES," filed September 25, 2019, which is incorporated by reference in its entirety. [Background technology]

[0002] background Microfluidic devices can include features such as channels, chambers, and wells. It can be difficult to fabricate microfluidic devices in which the layers of the microfluidic device are bonded to one another in a manner that avoids damaging the layers or distorting the dimensions of the device. Summary of the Invention

[0003] overview The present disclosure describes systems and methods for manufacturing microfluidic devices. The microfluidic devices can be sealed microfluidic devices. Such devices can include one or more features, such as channels, chambers, wells, or other voids, defined in a substrate or other solid part, which can be at least partially enclosed around the microfluidic features. For example, the microfluidic device can include a substrate or base part defining a channel, chamber, or well, and a cap part. The cap part can surround at least a portion of the channel, chamber, or well. In some embodiments, the cap part can include at least one opening in fluid communication with the channel, chamber, or well to allow fluid to be introduced into the microfluidic device. The base part and the cap part can be fabricated separately and glued or bonded together to form the microfluidic device. However, conventional bonding techniques can adversely affect the materials forming the base part and the cap part. For example, some bonding techniques can burn or melt a portion of the base part or the cap part. As a result, the microfluidic device can be distorted in dimensions as a result of such burning or melting.

[0004] To address the aforementioned problems, the present disclosure provides systems and methods for manufacturing sealed microfluidic devices in a manner that overcomes these challenges. In some embodiments, the shape and dimensions of the base or cap parts can be selected to facilitate injection molding in a manner that prevents or reduces deformation of the microfluidic device that might otherwise occur as a result of temperatures and pressures applied during the molding process or other bonding techniques.

[0005] At least one aspect of the present disclosure relates to a method. The method can include providing a base part for defining a first portion of a channel of a microfluidic device. The method can include fabricating a cap part of the microfluidic device. The cap part can include a sealing lip extending a first distance from a first side of the cap part and a support part extending a second distance. The second distance can be less than the first distance. The support part can extend from the first side of the cap part. The method can include disposing the cap part and the base part in a mold such that the sealing lip of the cap part contacts the base part. The base part can be spaced from the support part of the cap part by a third distance equal to the difference between the first distance and the second distance. The method can include injecting a polymer material into the mold to fill at least a portion of a cavity defined by the base part, the support part of the cap part, and the sealing lip of the cap part with the polymer material. The cavity can be sealed from the channel of the microfluidic device by the sealing lip of the cap part. The method may include curing the polymeric material to bond the base component to the cap component.

[0006] In some embodiments, the method can include forming an optical layer that includes a transparent material. In some embodiments, the method can include bonding the optical layer to one of the base or cap parts to facilitate viewing of the microfluidic device. In some embodiments, the method can include bonding the optical layer to one of the base or cap parts using at least one of laser welding, ultrasonic welding, solvent bonding, or thermal bonding. In some embodiments, the base and cap parts are formed from a material different from the polymeric material injected into the cavity.

[0007] In some embodiments, the polymeric material comprises at least one of a cyclic olefin polymer (COP), a cyclic olefin copolymer (COC), or polystyrene. In some embodiments, the cap part defines a ceiling or a sidewall of a channel of the microfluidic device. In some embodiments, the cap part includes a well plate defining at least one opening configured to be in fluid communication with the channel of the microfluidic device after hardening of the polymeric material. In some embodiments, the method can include fabricating the cap part including the well plate using injection molding. In some embodiments, the cap part is fabricated such that a sealing lip at least partially surrounds the at least one opening of the well plate. In some embodiments, the base part further defines at least a portion of a second channel. In some embodiments, the first channel and the second channel can be separated by a semi-permeable membrane.

[0008] In some embodiments, the method can include placing a first side of the membrane in contact with a first rigid support structure in a mold. In some embodiments, the method can include injection molding a first channel layer onto a second side of the membrane to adhere the first channel layer to a second side of the membrane (opposite the first side of the membrane). The first channel layer can define at least a portion of the first channel. In some embodiments, the method can include replacing the first rigid support structure with a second rigid support structure in a mold. The second rigid support structure can be in contact with the first side of the membrane. The second rigid support structure can have a shape corresponding to a second channel network including the second channels. In some embodiments, the method can include injection molding a second channel layer onto the first side of the membrane to adhere the second channel layer to the first side of the membrane. The second channel layer can define a second channel network including at least a portion of the second channels. In some embodiments, the cap component is fabricated such that a sealing lip of the cap component includes a beveled edge.

[0009] At least one other aspect of the present disclosure relates to a microfluidic device. The microfluidic device can include a base part defining at least a portion of a first channel of the microfluidic device. The microfluidic device can include a cap part including a sealing lip extending a first distance from a first side of the cap part and a support portion extending a second distance. The second distance can be less than the first distance. The support portion can extend from the first side of the cap part. The microfluidic device can include a polymeric material filling at least a portion of a cavity defined by the base part, the support portion of the cap part, and the sealing lip of the cap part. The cavity can be sealed from the channel of the microfluidic device by the sealing lip of the cap part. The polymeric material can be injection molded to fill the cavity and can harden to bond the base part to the cap part.

[0010] In some embodiments, the microfluidic device can include a second channel complementary to the first channel. The second channel can be at least partially defined by a base component of the microfluidic device. In some embodiments, the microfluidic device can include a semi-permeable membrane separating the first channel from the second channel. In some embodiments, the microfluidic device can include a well plate formed as part of a cap component of the microfluidic device. The well plate can define at least one opening in fluid communication with the first channel or the second channel of the microfluidic device. In some embodiments, the microfluidic device can include an optical layer coupled to the base component or the cap component to facilitate viewing of the microfluidic device.

[0011] At least one other aspect of the present disclosure relates to a method. The method can include placing a first side of a membrane in contact with a first rigid support structure in a mold. The method can include injection molding a first channel layer onto a second side of the membrane to adhere the first channel layer to a second side of the membrane (opposite the first side of the membrane). The first channel layer can define a first channel network. The method can include replacing the first rigid support structure with a second rigid support structure in the mold. The second rigid support structure can be in contact with the first side of the membrane. The second rigid support structure can have a shape corresponding to the second channel network. The method can include injection molding a second channel layer onto the first side of the membrane to adhere the second channel layer to the first side of the membrane. The second channel layer can define a second channel network. The method can include providing a well plate defining at least one opening. The well plate may include a sealing lip extending a first distance from a first side of the well plate and a support portion extending a second distance. The second distance may be less than the first distance. The support portion may extend from the first side of the well plate. The sealing lip may at least partially surround the at least one opening. The method may include placing the well plate in the mold such that the sealing lip of the well plate contacts the first channel layer and such that the at least one opening of the well plate is aligned with at least one channel of the first channel network. The first channel layer may be spaced from the support portion of the well plate by a third distance equal to the difference between the first distance and the second distance. The method may include injecting a polymer material into the mold to fill at least a portion of a cavity defined by the first channel layer, the support portion of the well plate, and the sealing lip of the well plate with the polymer material. The cavity may be sealed from the channel of the microfluidic device by the sealing lip of the cap part. The method can include curing the polymeric material to bond the well plate to the first channel layer.

[0012] [The present invention 1001] providing a base piece for defining a first portion of a channel of a microfluidic device; fabricating a cap part of the microfluidic device, the cap part including a sealing lip extending a first distance from a first side of the cap part and a support portion extending a second distance from the first side of the cap part that is less than the first distance; placing the cap part and the base part in a mold such that the sealing lip of the cap part contacts the base part, the base part being spaced from the support portion of the cap part a third distance equal to a difference between the first distance and the second distance; injecting a polymeric material into the mold to fill at least a portion of a cavity defined by the base part, the support portion of the cap part, and the sealing lip of the cap part with the polymeric material, the cavity being sealed from a channel of the microfluidic device by the sealing lip of the cap part; and curing the polymeric material to bond the base component to the cap component. A method comprising: [The present invention 1002] forming an optical layer comprising a transparent material; and bonding the optical layer to one of the base part or the cap part to facilitate viewing of the microfluidic device. The method of the present invention 1001 further comprises: [The present invention 1003] The method of claim 1002, further comprising bonding the optical layer to one of the base or cap components using at least one of laser welding, ultrasonic welding, solvent bonding, or thermal bonding. [The present invention 1004] The method of claim 1001, wherein said base component and said cap component are formed from a material different from a polymeric material injected into said cavity. [The present invention 1005] 1001. The method of claim 1001, wherein said polymeric material comprises at least one of a cyclic olefin polymer (COP), a cyclic olefin copolymer (COC), or polystyrene. [The present invention 1006] 1002. The method of claim 1001, wherein said cap part defines a ceiling or a sidewall of a channel of said microfluidic device. [The present invention 1007] 1001. The method of claim 1001, wherein the cap component comprises a well plate defining at least one opening configured to be in fluid communication with a channel of the microfluidic device after hardening of the polymer material. [The present invention 1008] The method of claim 1007, further comprising the step of fabricating said cap part containing said well plate using injection molding. [The present invention 1009] The method of claim 1007, wherein said cap part is fabricated such that said sealing lip at least partially surrounds said at least one opening in said well plate. [The present invention 1010] The method of claim 1001, wherein said channel is a first channel and said base component further defines at least a portion of a second channel. [The present invention 1011] The method of claim 1010, wherein said first channel and said second channel are separated by a semipermeable membrane. [The present invention 1012] The method of claim 1010, further comprising the step of injection molding at least a portion of said base component. [The present invention 1013] placing a first side of the membrane in contact with a first rigid support structure within a mold; injection molding the first channel layer onto a second side of the membrane opposite the first side of the membrane such that the first channel layer is adhered to the second side of the membrane, the first channel layer defining at least a portion of the first channel; replacing the first rigid support structure with a second rigid support structure in the mold, the second rigid support structure contacting the first side of the membrane, the second rigid support structure having a shape corresponding to a second channel network including the second channel; and injection molding a second channel layer onto the first side of the membrane so as to adhere the second channel layer to the first side of the membrane, the second channel layer defining the second channel network including at least a portion of the second channel. The method of the present invention 1012 further comprises: [The present invention 1014] The method of claim 1001, wherein the cap component is fabricated such that the sealing lip of the cap component includes a beveled edge. [The present invention 1015] 1. A microfluidic device comprising: a base component defining at least a portion of a first channel of the microfluidic device; a cap part including a sealing lip extending a first distance from a first side of the cap part and a support portion extending a second distance from the first side of the cap part that is less than the first distance; and a polymeric material filling at least a portion of a cavity defined by the base component, the support portion of the cap component, and the sealing lip of the cap component, the cavity being sealed from the channel of the microfluidic device by the sealing lip of the cap component. Including, the polymeric material is injection molded to fill the cavity and harden to bond the base component to the cap component; Microfluidic devices. [The present invention 1016] The microfluidic device of the present invention 1015, wherein the microfluidic device includes a second channel complementary to the first channel, the second channel being defined at least in part by the base component of the microfluidic device. [The present invention 1017] The microfluidic device of claim 1016, further comprising a semi-permeable membrane separating said first channel from said second channel. [The present invention 1018] The microfluidic device of the present invention 1016, wherein the microfluidic device further comprises a well plate formed as part of the cap component of the microfluidic device, the well plate defining at least one opening in fluid communication with the first channel or the second channel of the microfluidic device. [The present invention 1019] The microfluidic device of the present invention 1016, further comprising an optical layer coupled to said base part or said cap part to facilitate viewing of said microfluidic device. [The present invention 1020] placing a first side of the membrane in contact with a first rigid support structure within a mold; injection molding a first channel layer onto a second side of the membrane such that the first channel layer adheres to the second side of the membrane opposite the first side of the membrane, the first channel layer defining a first channel network; replacing the first rigid support structure with a second rigid support structure in the mold, the second rigid support structure contacting the first side of the membrane, the second rigid support structure having a shape corresponding to a second channel network; injection molding a second channel layer onto the first side of the membrane such that the second channel layer adheres to the first side of the membrane, the second channel layer defining the second channel network; providing a well plate defining at least one opening, the well plate including a sealing lip extending a first distance from a first side of the well plate and a support portion extending a second distance from the first side of the well plate that is less than the first distance, the sealing lip at least partially surrounding the at least one opening; placing the well plate within the mold so that the sealing lip of the well plate contacts the first channel layer and so that the at least one opening of the well plate is aligned with at least one channel of the first channel network, the first channel layer being spaced from the support portion of the well plate a third distance equal to a difference between the first distance and the second distance; injecting a polymeric material into the mold to fill at least a portion of a cavity defined by the first channel layer, the support portion of the well plate, and the sealing lip of the well plate with the polymeric material, the cavity being sealed from a channel of a microfluidic device by the sealing lip of a cap component; and curing the polymeric material to bond the well plate to the first channel layer. A method comprising: These and other aspects and embodiments are described in detail below. The foregoing information and the following detailed description include examples of the various aspects and embodiments and provide an overview or framework for understanding the nature and characteristics of the claimed aspects and embodiments. The drawings provide examples and further understanding of the various aspects and embodiments and are incorporated in and constitute a part of this specification. It will be readily understood that aspects can be combined and that features described in connection with one aspect of the invention may be combined with other aspects. The aspects can be realized in any convenient form. [Brief description of the drawings]

[0013] The accompanying drawings are not intended to be drawn to scale. Like numbers and designations in the various figures indicate like elements. For clarity, not every part is labeled in every drawing. The above and other objects, aspects, features, and advantages of the present disclosure will become more apparent and will be better understood by reference to the following description read in conjunction with the accompanying drawings.

[0014] [Figure 1] 1 shows an exploded view of an exemplary material stack for forming a microfluidic device. [Diagram 2] FIG. 2 shows a plan view of a portion of the microfluidic device shown in FIG. [Diagram 3] 2 illustrates a cross-sectional view of an exemplary material stack for forming a microfluidic device similar to that shown in FIG. 1. [Figure 4] 2 illustrates a cross-sectional view of another exemplary material stack for forming a microfluidic device similar to that shown in FIG. 1. [Diagram 5] 2 illustrates a cross-sectional view of another exemplary material stack for forming a microfluidic device similar to that shown in FIG. 1. [Figure 6] 1 shows a flow chart of an exemplary method for fabricating a closed microfluidic device. [Figure 7A] 7A-7C show cross-sectional views of stages in the construction of an exemplary microfluidic device manufactured according to the exemplary method of FIG. 6. [Figure 7B] 7A-7C show cross-sectional views of stages in the construction of an exemplary microfluidic device manufactured according to the exemplary method of FIG. 6. [Figure 7C] 7A-7C show cross-sectional views of stages in the construction of an exemplary microfluidic device manufactured according to the exemplary method of FIG. 6. [Figure 7D] 7A-7C show cross-sectional views of stages in the construction of an exemplary microfluidic device manufactured according to the exemplary method of FIG. 6. [Figure 7E] 7A-7C show cross-sectional views of stages in the construction of an exemplary microfluidic device manufactured according to the exemplary method of FIG. 6. [Figure 7F] 7A-7C show cross-sectional views of stages in the construction of an exemplary microfluidic device manufactured according to the exemplary method of FIG. 6. [Figure 7G] 7A-7C show cross-sectional views of stages in the construction of an exemplary microfluidic device manufactured according to the exemplary method of FIG. 6. [Figure 8] 7A-7G depict cross-sectional views of alternative configurations of parts of the microfluidic device shown in FIG. [Figure 9] 1 shows a flow chart of an exemplary method for fabricating a closed microfluidic device. [Figure 10] 10A-10C show cross-sectional views of material stacks that can be used to form a closed microfluidic device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Detailed Description The various concepts introduced above and described in further detail below are not limited to any particular implementation and may be implemented in any of numerous ways. Examples of specific embodiments and applications are provided primarily for illustrative purposes.

[0016] The present disclosure describes systems and methods for manufacturing microfluidic devices. The microfluidic devices can be sealed microfluidic devices. Such devices can include one or more features, such as channels, chambers, wells, or other voids, defined in a substrate or other rigid component, which can be at least partially enclosed around the microfluidic features. For example, the microfluidic device can include a substrate or base component that defines a channel, chamber, or well, and a cap component. The cap component can surround at least a portion of the channel, chamber, or well. In some embodiments, the cap component can include at least one opening in fluid communication with the channel, chamber, or well to allow fluid to be introduced into the microfluidic device.

[0017] The base and cap parts can be fabricated separately and glued or bonded together to form a microfluidic device. However, conventional bonding techniques can adversely affect the materials forming the base and cap parts. For example, some bonding techniques can burn or melt portions of the base or cap parts. As a result, the microfluidic device can become dimensionally distorted as a result of such burning or melting. The present disclosure provides systems and methods for manufacturing sealed microfluidic devices in a manner that overcomes these challenges. In some embodiments, the shape and dimensions of the base or cap parts can be selected to facilitate injection molding in a manner that prevents or reduces deformation of the microfluidic device that might otherwise occur as a result of the temperature and pressure applied during the molding process.

[0018] FIG. 1 shows an exploded view of an exemplary material stack for forming a microfluidic device 100. The microfluidic device 100 can include multiple layers forming the material stack. For example, the microfluidic device 100 can include a bottom channel layer 105 and a top channel layer 110. The bottom channel layer 105 and the top channel layer 110 can be separated from each other by a permeable membrane 115. The bottom channel layer 105 and the top channel layer 110 can each define a respective network of one or more channels. The channels in the base channel layer 105 can be complementary to the respective channels in the top channel layer 110. For example, portions of the channels in the top channel layer 110 can overlap portions of the channels in the base channel layer 105, with the overlapping portions in fluid communication with each other via the membrane 115. As a result, interactions can occur between substances in the channels of the base channel layer 105 and substances in the channels of the top channel layer 110.

[0019] The microfluidic device 100 also includes a port layer 120. The port layer 120 can include openings or ports that can be aligned with channels in either the base channel layer 105 or the top channel layer 110. Fluid samples can be introduced into the channels of the base channel layer 105 and the top channel layer 110 through the ports of the port layer 120. The microfluidic device 100 can also include an optical layer 125. The optical layer 125 can provide optical access to the channels of the base channel layer 105. For example, the optical layer 125 can act as an interface through which materials (e.g., fluid samples, cells, etc.) can be observed or imaged, such as with a microscope or other optical instrument. The microfluidic device 100 can also include additional or different layers that are not shown in FIG. 1. For example, the microfluidic device 100 can include or be coupled to a well plate. The well plate can be integrated with the port layer 120. The well plate can also be formed separately from the port layer 120 and positioned to interface with the port layer 120 .

[0020] The microfluidic device 100 can be formed by bonding the layers shown in FIG. 1 together. However, conventional bonding techniques applied to these layers can cause problems in the resulting microfluidic device 100. For example, bonding can require exposure of the layers to heat and pressure for long, repeated bonding cycles. This can lead to shrinkage of certain portions of the layers, thereby resulting in misalignment between adjacent layers. In some embodiments, the layers of the microfluidic device 100 can be formed from polymeric materials such as cyclic olefin polymer (COP), cyclic olefin copolymer (COC), or polystyrene. However, material selection can further complicate the bonding process. For example, there can be a mismatch in the thermal expansion coefficients of materials used for adjacent layers, which can smear or distort one or more layers during the bonding process, which requires heating. In some instances, either or both of the membrane 115 or the optical layer 125 can distort and thus exhibit insufficient "flatness" after the bonding process, leading to poor performance of the microfluidic device 100.

[0021] FIG. 2 shows a plan view of a portion of the microfluidic device 100 shown in FIG. 1. FIG. 2 shows a channel 205 in the base channel layer 105 and another channel 210 in the top channel layer 110. The channel 205 can be formed as part of the base channel layer 105, for example, as a recess or a defined open area in the substrate of the base channel layer 105. Similarly, the other channel 210 can be formed as part of the top channel layer 110, for example, as a recess or a defined open area in the substrate of the top channel layer 110. The channels 205 and 210 can each include a central portion and an arm portion. The central portions of the channels 205 and 210 can overlap each other. In some embodiments, the central portions of the channels 205 and 210 can be separated from each other by a membrane 115 (not shown in FIG. 2) such that the channels 205 and 210 are in fluid communication with each other through the membrane 115. Channels 205 and 210 can be separated by any type of membrane or separating layer (eg, a scaffold, semi-permeable membrane, or other type of separating layer).

[0022] In some embodiments, the arm portions of the channels 205 and 210 can extend in various directions, including in opposite directions, and the channels 205 and 210 may not be perfectly aligned with each other along their entire length. As a result, sections of the base channel layer 105 that are disposed adjacent to the arm portions of the channels 210 defined by the top channel layer 110 may not be supported by the top channel layer 110 itself during the bonding process. Similarly, sections of the top channel layer 110 that are disposed adjacent to the arm portions of the channels 205 defined by the base channel layer 105 may not be supported by the base channel layer 105 itself. These unsupported sections may collapse (collapse) into the arm portions of the underlying channels in the adjacent layers when exposed to temperature and pressure during the bonding process. This may result in further material deformation of the layers and poor bond quality.

[0023] 3 shows a cross-sectional view of an exemplary material stack 300 for forming a microfluidic device similar to the microfluidic device 100 shown in FIG. The stack 300 can include at least one base channel layer 305, at least one membrane 320, and at least one top channel layer 340. The membrane 320 can separate the base channel layer 305 from the top channel layer 340. The stack 300 also includes a well plate 360.

[0024] In some embodiments, the layers of the stack 300 can be formed separately from one another. After formation, the layers can be bonded together to form a complete microfluidic device, such as the microfluidic device 100 shown in FIG. 1. For example, the layers can be bonded together by ultrasonic welding (sometimes referred to as "ultrasonic bonding"). Ultrasonic welding can include subjecting the layers of the stack 300 to high frequency vibrations, which can generate heat at the interfaces of adjacent layers of the stack 300. However, ultrasonic welding can require that the materials exposed to the high frequency vibrations are compatible with one another. For example, ultrasonic welding requires material compatibility between adjacent layers (e.g., the COP / COP or COP / COC used for adjacent layers and that of the semipermeable membrane 320) such that the adjacent layers have similar glass transition temperatures, which can limit the design options of the material stack 300. Additionally, ultrasonic bonding can result in significant "flash," i.e., excess material. This excess material can block or obstruct portions of the microfluidic device 100, or can otherwise cause undesirable results.

[0025] In some embodiments, one or more pairs of adjacent layers in the stack 300 may be bonded together using ultrasonic welding, while other pairs of adjacent layers in the stack 300 may be bonded using other techniques. In some other embodiments, the base channel layer 305, membrane 320, and top channel layer 340 may be bonded using other means, and the well plate 360 ​​may be attached to the top channel layer 340 by ultrasonic bonding. In either case, ultrasonic bonding may result in poor bond uniformity in areas where the ultrasonic energy is insufficient, leading to the risk of either or both of the base channel layer 305 and the top channel layer 340 collapsing or deforming into their respective channels.

[0026] In some embodiments, one or more pairs of adjacent layers in the stack 300 may instead be bonded using insert molding techniques. For example, the base channel layer 305, the membrane 320, and the top channel layer 340 may first be adhered together by any bonding technique, and then the well plate 360 ​​may be overmolded onto the top channel layer 340 in a mold. However, like ultrasonic bonding, insert molding techniques may incur the risk that either or both of the base channel layer 305 and the top channel layer 340 may collapse or deform into their respective channels when temperature and pressure are applied in the mold.

[0027] FIG. 4 illustrates a cross-sectional view of another exemplary material stack 400 for forming a microfluidic device similar to the microfluidic device 100 illustrated in FIG. 1. The stack 400 can be similar to the stack 300 illustrated in FIG. 3, although the particular layer illustrated in FIG. 3 is formed from multiple layers in the stack 400 of FIG. 4. For example, in the stack 400, a base channel layer (such as, for example, the base channel layer 305 previously described in connection with FIG. 3) can be formed from a first layer 405 and a second layer 410, and a top channel layer (such as, for example, the top channel layer 340 previously described in connection with FIG. 3) can be formed from a first layer 440 and a second layer 445. A membrane 420 can separate the base channel layer from the top channel layer. In particular, the membrane 420 can be disposed between the layer 410 forming a portion of the base channel layer and the layer 440 forming a portion of the top channel layer. The stack 400 also includes a well plate 460.

[0028] In some embodiments, one or more of the layers of the stack 400 can be formed separately from one another. The layers can be bonded together to form a complete microfluidic device. In some embodiments, at least some pairs of adjacent layers in the stack 400 can be bonded together using laser welding. In a laser welding process, laser energy can be passed through one layer and absorbed by another layer to heat and melt the interface between the two layers. Therefore, the materials of the adjacent layers must be carefully selected. In addition, laser welding can risk burning or deforming a portion of the layer. The bonding of the membrane 420 to the adjacent layers 420 and 440 can also be poor in unsupported areas, resulting in leakage paths.

[0029] FIG. 5 illustrates a cross-sectional view of an exemplary material stack 500 for forming a microfluidic device similar to the microfluidic device 100 illustrated in FIG. 1. The stack 500 can be similar to the stack 400 illustrated in FIG. 4 or the stack 300 illustrated in FIG. 3, but certain layers of the stack 400 illustrated in FIG. 4 or the stack 300 illustrated in FIG. 3 can be integrally formed with each other in the stack 500 of FIG. 5. For example, in the stack 500, the top channel layer (e.g., formed from the first layer 440 and the second layer 445 in the stack 400 of FIG. 4, formed from the base channel layer 340 in the stack 300 of FIG. 3, etc.) can be integrally formed with the well plate as an integrated top channel 560. In some embodiments, the integrated top channel 560 illustrated in FIG. 5 can be formed by injection molding. In some embodiments, the integrated top channel 560 can be formed by other manufacturing processes such as those described herein. The stack 500 can include a base channel layer formed from layers 505 and 510 (eg, similar to layer 405 and second layer 410 , etc.) and a membrane 520 .

[0030] In some embodiments, layers below the well plate 560 of the stack 500 can be sequentially attached to one another by laser welding to create the final microfluidic device. However, laser welding can include defects similar to those described above in connection with FIG. 4. For example, burning or material deformation can occur, especially since multiple successive laser welds may be required. Similarly, insufficient bonding can occur between the membrane 520 and adjacent layers, and in some circumstances, the membrane 520 can exhibit insufficient flatness.

[0031] Figure 6 shows a flow chart of an exemplary method 600 for fabricating a closed microfluidic device. Figures 7A-7G show cross-sectional views of stages of construction of an exemplary microfluidic device manufactured according to the exemplary method 600 of Figure 6. Figures 6 and 7A-7G are discussed together below.

[0032] Referring now to FIG. 6, the method 600 can include placing the membrane in contact with a first rigid support structure (block 605). The method 600 can include injection molding a first channel layer over the membrane (block 610). The method 600 can include replacing the first rigid support structure with a second rigid support structure in a mold (block 615). The method 600 can include injection molding a second channel layer (block 620). The method 600 can include providing a well plate (block 625). The method 600 can include placing the well plate in a mold (block 630). The method 600 can include injecting a polymer material into the mold to fill a cavity defined by portions of the first channel layer and the well plate (block 635). The method 600 can include curing the polymer material (block 640).

[0033] Referring again to FIG. 6 in more detail, the method 600 can include placing the membrane in contact with a first rigid support structure (block 605). The result of this step is shown in FIG. 7A. As shown, the first rigid support structure 705 can include a rectangular cross-sectional shape. Such a shape can provide a flat surface upon which the membrane 720 can be placed. For example, the flat surface provided by the first rigid support structure 705 can help ensure that the membrane 720 maintains a flat or planar shape. In some embodiments, the membrane 720 can be similar to the membranes 115, 320, 420, and 520 shown in FIGS. 1 and 3-5. For example, the membrane can be a layer of material formed from a polymer, such as polycarbonate, that defines a series of pores having pore sizes selected to allow particles of a desired size or weight to pass through the membrane 720. In some embodiments, the rigid support structure 705 can have localized features that can allow tensioning of the membrane 720. For example, the shape of the rigid support structure 705 can be selected to provide tension to the membrane 720 .

[0034] The method 600 can include injection molding the first channel layer onto the membrane (block 610). The result of this step is shown in FIG. 7B. Another insert or support structure 715 can be used to form a mold for this step. The support structure 715 can be located on the opposite side of the membrane 720 from the first support structure 705. In some embodiments, the support structure 715 can be formed with an opposite contour to the first channel layer 710. For example, the support structure 715 can have voids in areas where the first channel layer 710 is solid and can be solid in areas that define voids (e.g., channels, chambers, etc.) in the first channel layer 710. A polymeric material such as COC, COP, or polystyrene, among others, can be injected into the mold to fill the voids in the support structure 715, thereby defining the first channel layer 710.

[0035] The method 600 may include replacing the first rigid support structure 705 with a second rigid support structure in the mold (block 615). The result of this step is shown in FIG. 7C. As shown, the first support structure 705 has been removed and a second rigid support structure 725 has been placed in its place. The first rigid support structure 705 may be removed, for example, by mechanical removal or by dissolving or otherwise removing the first support structure 705 using a solvent or other chemical reaction. Unlike the first support structure 705, the second rigid support structure 725 may not have a rectangular cross-sectional shape. Instead, the second rigid support structure 725 may have a shape selected according to the desired shape of the second channel layer to be formed in subsequent processing. In some embodiments, the second support structure 725 may be formed with an opposite contour to the second channel layer. For example, the second support structure 725 can have voids in areas where the second channel layer is solid and can be solid in areas that define voids (e.g., channels, chambers, etc.) in the second channel layer. In some embodiments, the second rigid support structure 725 can have a shape similar to that of the support structure 715. As a result, the second rigid support structure 725 can be used to create a second channel layer having a channel network that is complementary to the channel network defined by the first channel layer 710. In this disclosure, channels may be referred to as "complementary" when portions of the channels overlap one another. In some embodiments, a membrane, such as membrane 720, can separate overlapping portions of the complementary channels. In some embodiments, a channel and its complement can be in fluid communication with one another via membrane 720.

[0036] The method 600 may include injection molding the second channel layer (block 620). The result of this step is shown in FIG. 7D. In some embodiments, a polymeric material, such as COC, COP, or polystyrene, among others, may be injected into the mold to fill the voids in the second support structure 725, thereby defining the second channel layer 730. In some embodiments, the material selected for the second channel layer 730 may be the same as the material selected for the first channel layer 710. In some embodiments, the material selected for the second channel layer 730 may be different from the material selected for the first channel layer 710.

[0037] The method 600 can include providing a well plate (block 625). In some embodiments, the well plate can be manufactured separately from the first channel layer 710 and the second channel layer 730 shown in FIGS. 7A-7D. In some embodiments, the well plate can be made using a separate injection molding technique. An example of such a technique is shown in FIG. 7E. As shown, a first mold piece 745 and a second mold piece 750 can be used. A polymeric material such as COC, COP, or polystyrene, among others, can be injected into the recessed space defined by the first mold piece 745 and the second mold piece 750 to form the well plate 760. In some embodiments, the material selected for the well plate 760 can be the same as the material selected for either or both of the first channel layer 710 or the second channel layer 730. In some embodiments, the material selected for the second channel layer 730 can be different from the material selected for either or both of the first channel layer 710 and the second channel layer 730.

[0038] Well plate 760 can be similar to well plates 360, 460, and 560 shown in FIGS. 3-5. For example, well plate 760 can include at least one central opening (e.g., defined by second mold piece 750) through which a fluid sample can be introduced into an underlying channel or chamber after well plate 760 is affixed to the remainder of the microfluidic device. However, well plate 760 can differ from well plates 360, 460, and 560 in that well plate 760 can include a sealing lip 762, which may also be referred to herein as sealing portion 762. Sealing lip 762 can protrude from the remainder of well plate 760 (which may be referred to as the support portion of well plate 760). Sealing lip 762 can at least partially surround an opening 764 defined by well plate 760. In contrast to conventional well plates that do not include a sealing lip, as described further below, a well plate 760 having a sealing lip 762 can be used to facilitate an improved bonding process that can provide better bonding quality and less risk of damage to the well plate 760 or other parts of the microfluidic device (e.g., channel layers, membranes, etc.).

[0039] The method 600 may include placing a well plate in a mold (block 630). The well plate 760 may be placed in the mold such that a sealing lip 762 of the well plate 760 contacts the first channel layer 710. Also, the opening of the well plate 760 may be aligned with the channel defined by the first channel layer 710. When the sealing lip 762 is in contact with the first channel layer 710, the sealing lip 762 may act as a seal surrounding the opening of the well plate 760.

[0040] As shown in FIG. 7F, when the sealing lip 762 is placed in contact with the first channel layer 710, a gap can exist between the remainder of the well plate 760 and the first channel layer 710. The gap can have a height that extends a distance labeled d2 in FIG. 7F and a width that extends a distance labeled d3 in FIG. 7F. In other words, to a first end (e.g., top end) of the well plate 760, the support portion can extend a distance labeled d1 in FIG. 7F, and the sealing lip 762 extends an additional distance d2. As a result, a cavity 770 can exist between the well plate 760 and the first channel layer 710. The cavity can span a width having a distance d3 and a height having a distance d2. The cavity 770 is sealed by the sealing lip 762 from a channel defined in the first channel layer 710.

[0041] The method 600 may include injecting a polymer material into the mold to fill a cavity 770 defined by the first channel layer 710 and a portion of the well plate 760 (block 635). The polymer material may be injected into the cavity 770. The injected polymer material is prevented from leaking into the channel because a sealing lip 762 seals the cavity 770 from the channel. In some embodiments, the injection of the polymer material may be achieved through an injection molding process. In addition, the injected polymer material may bond the well plate 760 to the first channel layer 710. This bonding technique therefore provides several technical improvements over conventional laser welding, ultrasonic welding, and other techniques mentioned above. For example, burning or warping of the materials of the well plate 760 and the first channel layer 710 may be avoided because there is no need to use techniques such as laser welding that may expose the materials to temperatures that may cause such damage.

[0042] Additionally, a secure bond can be formed between the well plate 760 and the first channel layer 710 without the risk of crushing any portion of the first channel layer 710, the membrane 720, or the second channel layer 730. For example, as described above, bonding techniques that require the application of pressure to the material stack can cause layers of the stack to deform out of plane (e.g., collapse (collapse) into channels or chambers defined by adjacent layers) in areas where there may not be a rigid substrate or other support structure to prevent such collapse. Using the techniques described in this disclosure, including providing a well plate 760 with a sealing lip 762 and injecting a polymeric material to fill the cavity 770 between the well plate 760 and the adjacent first channel layer 710, can eliminate the need to apply pressure, which can increase the risk of layers collapsing during the bonding process.

[0043] In some embodiments, the dimensions of the sealing lip 762 and the cavity 770 can be selected to facilitate a strong bond between the well plate 760 and the first channel layer 710. In some embodiments, the distance d2 (e.g., the height of the sealing lip 762, or the distance that the sealing lip 762 protrudes from the support portion of the well plate 760) can be selected to be about 1%, about 5%, about 10%, about 15%, about 20%, or any other magnitude between 1% and 20% (inclusive) of the distance d1. In some embodiments, the distance d3 (e.g., the width of the cavity 770) can be selected to be substantially equal to the distance d2. In some other embodiments, the distance d3 can be selected to be about 25% greater than the distance d2, about 50% greater than the distance d2, or about 75% greater than the distance d2. In still other embodiments, the distance d3 can be selected to be about twice the distance d2, about three times the distance d2, about four times the distance d2, or about five times the distance d2. Other dimensions are also possible.

[0044] The result of block 635 is shown in Figure 7G. As shown, the well plate 760 and the first channel layer 710 are bonded by the injection of a polymer material in block 635 to form what appears to be a monolithic part after the injection of the polymer material is completed. A dashed line 785 indicates the interface area between the first channel layer 710 and the well plate 760 for illustrative purposes, but it should be understood that in reality the well plate 760 and the first channel layer 710 may appear to be a single integral part after the bonding process is completed.

[0045] The method 600 may include hardening the polymer material injected into the cavity 770 (block 640). In some embodiments, the polymer material injected into the cavity 770 may be the same material as at least one of the well plate 760 and the first channel layer 710. For example, the well plate 760, the first channel layer 710, and the polymer material injected into the cavity may each be selected to be the same material or may be selected to be materials that are compatible with each other for bonding purposes by the injection molding techniques described in this disclosure. In some embodiments, the polymer material injected into the cavity 770 may be COP, COC, or polystyrene, among others.

[0046] In some embodiments, the method 600 can include additional steps or steps different from those shown in FIG. 6. For example, additional or different layers or components can be added to the microfluidic device in other steps. In some embodiments, the method 600 can include bonding an optical layer to the microfluidic device. For example, as shown in FIG. 7G, an optical layer 785 can be added to the second channel layer 730 on the side of the second channel layer 730 opposite the membrane 720 and the first channel layer 710. The second rigid support structure 725 can be removed before adding the optical layer 785. The optical layer 785 can be similar to the optical layer 125 shown in FIG. 1. The optical layer 785 can be formed from a transparent material and can facilitate viewing of the fluid sample or other substances in the channels defined in the second channel layer 730. The optical layer 785 can be made from other types of transparent materials, such as clear plastic or glass. In some embodiments, the optical layer 785 can be bonded to the microfluidic device via one or more attachment processes described herein, including laser welding, ultrasonic welding, solvent bonding, or thermal bonding.

[0047] FIG. 8 shows a cross-sectional view of an alternative form of the components of the microfluidic device shown in FIGS. 7A-7G. The components of FIG. 8 are similar to the components shown in FIGS. 7A-7G, and like numbers in these figures refer to like components. The device shown in FIG. 8 differs from the device shown in FIGS. 7A-7G in that the well plate 860 of FIG. 8 includes a sealing lip 862 having a beveled edge 895 rather than a straight edge. The beveled edge 895 extends downward at an angle away from the remainder of the well plate 860. In addition, the first channel layer 810 also includes a beveled edge having an angle matching the angle of the beveled edge 895, such that the beveled edge of the sealing lip 862 lies flush against the edge of the first channel layer 810. To bond the well plate 860 to the first channel layer 810, a polymer material can be injected into the cavity 870, similar to the process described above in connection with FIGS. 6 and 7A-7G.

[0048] The angle of the beveled edge 895 of the sealing lip 862 may cause the sealing lip 862 to exert an outward force on the first channel layer 810 (e.g., away from the central axis of the opening of the well plate 860). As described above, the membrane 820 may be bonded or adhered to the first channel layer 810. Thus, the outward force exerted by the beveled edge 895 of the sealing lip 862 on the first channel layer 810 may apply tension to the membrane 820, thereby increasing the flatness of the membrane 820. As a result, the membrane 820 may be less likely to collapse or deform out of plane (e.g., into a channel defined in the first channel layer 810 or the second channel layer 830).

[0049] It should be understood that the fabrication techniques described above in connection with Figure 6 can be used to create devices other than those shown in Figures 7A-7G and 8. For example, similar techniques can be applied to any enclosed microfluidic device, which may include devices that define features such as channels or chambers that are at least partially enclosed on their top and bottom surfaces. Figure 9 shows a flow chart of an exemplary method 900 for making such an enclosed microfluidic device.

[0050] Referring now to FIG. 9, the method 900 can include providing a base component (block 905). In some embodiments, the base component can define a first portion of the channels or chambers of the microfluidic device. For example, the base component can be a channel layer similar to either the first channel layer 710 or the second channel layer 730 shown in FIGS. 7A-7G. The base component can also include additional features. For example, the base component itself can include multiple layers, each of the multiple layers can define a respective channel or chamber (or a respective network of channels or chambers). The base component can be formed from a polymeric material, such as, for example, COC, COP, or polystyrene.

[0051] The method 900 can include fabricating a cap part of the microfluidic device (block 910). In some embodiments, the cap part can include a sealing lip. For example, the sealing lip can be similar to the sealing lip 762 shown in FIG. 7E. The sealing lip can extend a first distance from a first side of the cap part. The sealing lip can protrude from a support portion of the cap part, and the support portion can extend a second distance from the first side of the cap part that is less than the first distance. The cap part can be a well plate similar to the well plate 760 of FIGS. 7A-7G. In some other embodiments, the cap part can be a simpler part that may not include an opening that provides access to the interior channel. For example, instead, the cap part can define the sidewalls and ceiling or floor of the channel or chamber, similar to the first channel layer 710 or the second channel layer 730 shown in FIGS. 7A-7G, and a sealing lip can be added. In some embodiments, the cap part can be formed from a polymeric material such as COC, COP, or polystyrene, among others. In some embodiments, the cap component can be formed from the same material as the base component.

[0052] The method can include placing the cap part and the base part in a mold (block 915). In some embodiments, the cap part and the base part can be placed in the mold such that a sealing lip of the cap part is contacted with the base part. The base part can be spaced from the support portion of the cap part by a third distance equal to the difference between the first distance and the second distance. The base part, the support portion of the cap part, and the sealing lip of the cap part can together define a cavity that is sealed from a channel of the microfluidic device by the sealing lip of the cap part.

[0053] The method may include injecting a polymeric material into the mold to fill at least a portion of the cavity defined by the base part, the support portion of the cap part, and the sealing lip of the cap part with the polymeric material (Block 920). The injected polymeric material may bond the base part to the cap part. In some embodiments, the polymeric material may be the same material as one or both of the base part and the cap part. For example, the base part, the cap part, and the polymeric material injected into the cavity may each be selected to be the same material or may be selected to be materials that are compatible with each other for bonding purposes by the injection molding techniques described in this disclosure. In some embodiments, the polymeric material injected into the cavity may be COP, COC, or polystyrene.

[0054] The method may also include curing the polymer material to bond the base component to the cap component (block 925). After the polymer material has cured, the base component and the cap component may be combined to form what appears to be a monolithic microfluidic device. In some embodiments, other components may be added to the microfluidic device in further steps. For example, an optical layer may be added to allow for viewing or imaging of a fluid sample or other material within the microfluidic device.

[0055] 10A-10C show cross-sectional views of material stacks that can be used to form a sealed microfluidic device. The material stacks shown in FIGS. 10A-10C illustrate the difference between devices manufactured using conventional bonding techniques and devices made using the injection molding techniques described in this disclosure. Referring to FIG. 10A, a material stack 1010 is shown. The material stack 1010 includes a cap part 1015 and a base part 1020. The cap part 1015 and the base part 1020 meet at a flat interface suitable for bonding by conventional techniques. As mentioned above, such techniques typically require at least one temperature or pressure that runs the risk of damaging parts of the device, for example by burning the material or deforming or crushing the material.

[0056] In contrast, Figures 10B and 10C show material stacks that utilize sealing lips to facilitate bonding by injection molding, as described above. In some embodiments, the material stacks of Figures 10B and 10C can be bonded together to produce a sealed microfluidic device using the method 900 described above in connection with Figure 9. Referring now to Figure 10B, a material stack 1050 is shown. The material stack 1050 includes a cap part 1055 and a base part 1060. The cap part 1055 includes a sealing lip 1065 that extends away from the remainder of the cap part 1055. As shown in Figure 10B, when the cap part 1055 is brought into contact with the base part 1060, the sealing lip 1065 of the cap part 1055 abuts against a flat surface of the base part 1060, leaving a cavity 1070 sealed off from the central channel of the device. A polymer material can be injected into the cavity 1070 to bond the cap part 1055 to the base part 1060. A polymeric material can bond the cap component 1055 to the base component 1060, and a sealing lip 1065 prevents the injected polymeric material from leaking into the central channel of the device.

[0057] Similarly, FIG. 10C shows a material stack 1085 having a cap part 1085 and a base part 1090. The cap part 1085 includes a sealing lip 1095. Unlike the sealing lip 1065 shown in FIG. 10B, the sealing lip 1095 in FIG. 10C extends across a central channel defined between the cap part 1085 and the base part 1090, rather than surrounding the channel. When the cap part 1085 is placed in contact with the base part 1090 in the configuration shown in FIG. 10C, a cavity 1098 exists outside of the lip 1098. The cavity 1098 is sealed from the central channel of the device. A polymer material can be injected into the cavity 1095 to bond the cap part 1085 to the base part 1090. The polymer material can bond the cap part 1085 to the base part 1090, with the sealing lip 1095 preventing the injected polymer material from leaking into the central channel of the device.

[0058] It should be understood that the shapes of the material stacks shown in Figures 10B and 10C are exemplary only, and that microfluidic devices can also be fabricated using material stacks including sealing lips to define cavities of other shapes. For example, in the examples of Figures 10B and 10C, the sealing lip can instead be part of the base part, rather than part of the cap part. Other variations are also possible. These configurations can solve technical challenges when using conventional bonding techniques and material stack shapes that can adversely affect the materials forming the base and cap parts. For example, as noted above, some bonding techniques can burn or melt portions of the base or cap parts. As a result, the microfluidic device can be dimensionally distorted as a result of such burning or melting. The manufacturing techniques provided in this disclosure enable the creation of sealed microfluidic devices in a manner that solves these challenges. In some embodiments, the shapes and dimensions of the base or cap parts can be selected to facilitate injection molding in a manner that prevents or reduces deformation of the microfluidic device that may otherwise occur as a result of the temperature and pressure applied during the molding process.

[0059] Although operations are shown in a particular order in the figures, such operations do not have to be performed in the particular order or sequence shown, nor do all of the operations shown have to be performed. Operations described herein can be performed in different orders.

[0060] The separation of various system parts need not be required in all embodiments, and the program components described may be included in a single hardware or software product.

[0061] Having now described several exemplary embodiments, it will be apparent that the foregoing is presented by way of example and not limitation. In particular, while many of the examples presented herein include specific combinations of method operations or system elements, those operations and those elements may be combined in other ways to achieve the same purpose. Operations, elements, and features described in connection with one embodiment are not intended to be excluded from a similar role in other embodiments.

[0062] The terms and terminology used herein are for the purpose of explanation and should not be considered limiting. The use of "comprises," "has," "contains," "features," and variations thereof herein means to include the preceding item, its equivalents and further items, and alternative embodiments consisting of the following item exclusively. In one embodiment, the systems and methods described herein consist of one, a combination of two or more, or all of the described elements, operations, or components.

[0063] As used herein, the terms "about" or "substantially" will be understood by those of ordinary skill in the art and will vary to some extent depending on the context in which they are used. If there are uses of the term which are not clear to persons of ordinary skill in the art given the context in which it is used, "about" will mean up to ±10% of the particular term.

[0064] Any reference herein to system and method embodiments or elements or acts in the singular may also encompass embodiments including a plurality of those elements, and any reference herein to any embodiment or element or act in the plural may also encompass embodiments including only a single element. References in the singular or plural are not intended to limit the systems or methods disclosed herein, their parts, acts or elements to the singular or plural form. References to any act or element that is based on any information, act or element may include embodiments in which the act or element is based at least in part on any information, act or element.

[0065] Any embodiment disclosed herein may be combined with any other embodiment or aspect, and references such as "an embodiment," "some embodiments," "an embodiment," and the like are not necessarily mutually exclusive and are intended to indicate that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or aspect. Such terms as used herein do not necessarily all refer to the same embodiment. Any embodiment may be combined with any other embodiment, inclusively or exclusively, in any manner consistent with the aspects and embodiments disclosed herein.

[0066] The indefinite articles "a" and "an" as used in the specification and claims, unless clearly indicated otherwise, should be understood to mean "at least one."

[0067] References to "or" may be construed as inclusive, such that any term described using "or" may refer to only one, more than one, and all of the described terms. For example, a reference to "at least one of 'A' and 'B'" can include only 'A', only 'B', and both 'A' and 'B'. Such references used with "including" or other open-ended terms can include additional items.

[0068] Where a technical feature in a drawing, the detailed description, or any claim is followed by a reference number, such reference number is included to enhance the comprehensibility of the drawing, the detailed description, and the claims, and thus the reference number or its absence shall not have any limiting effect on the scope of any claim element.

[0069] The devices, systems and methods described herein may be embodied in other specific forms without departing from their characteristics. The above embodiments are illustrative rather than limiting of the described devices, systems and methods. Thus, the scope of the devices, systems and methods described herein is indicated by the appended claims, rather than by the above detailed description, and all changes that come within the meaning and range of equivalence of the claims are intended to be embraced therein.

Claims

1. providing a base piece for defining a first portion of a channel of a microfluidic device; preparing a cap part of the microfluidic device, the cap part including a sealing lip extending downwardly from a top side of the cap part a first distance and a support portion extending downwardly from the top side of the cap part a second distance less than the first distance; placing the cap part and the base part in a mold such that the sealing lip of the cap part contacts the base part, the base part being spaced from the support portion of the cap part a third distance equal to a difference between the first distance and the second distance; injecting a polymeric material into the mold to fill at least a portion of a cavity defined by the base part, the support portion of the cap part, and the sealing lip of the cap part with the polymeric material, the cavity being sealed from a channel of the microfluidic device by the sealing lip of the cap part; and curing the polymeric material to bond the base component to the cap component. A method comprising:

2. forming an optical layer comprising a transparent material; and bonding the optical layer to one of the base part or the cap part to facilitate viewing of the microfluidic device.

2. The method of claim 1, further comprising:

3. The method of claim 2 , further comprising bonding the optical layer to one of the base or cap components using at least one of laser welding, ultrasonic welding, solvent bonding, or thermal bonding.

4. The method of claim 1 , wherein the base component and the cap component are formed from materials different than the polymeric material injected into the cavity.

5. The method of claim 1 , wherein the polymeric material comprises at least one of a cyclic olefin polymer (COP), a cyclic olefin copolymer (COC), or polystyrene.

6. The method of claim 1 , wherein the cap part defines a ceiling or a sidewall of a channel of the microfluidic device.

7. 10. The method of claim 1, wherein the cap component comprises a well plate defining at least one opening configured to be in fluid communication with a channel of the microfluidic device after the polymer material has hardened.

8. 8. The method of claim 7, further comprising fabricating the cap part containing the well plate using injection molding.

9. The method of claim 7, wherein the cap component is fabricated such that the sealing lip at least partially surrounds the at least one opening in the well plate.

10. The method of claim 1 , wherein the channel is a first channel and the base component further defines at least a portion of a second channel.

11. 11. The method of claim 10, wherein the first channel and the second channel are separated by a semi-permeable membrane.

12. The method of claim 10 , further comprising injection molding at least a portion of the base component.

13. placing a first side of the membrane in contact with a first rigid support structure within a mold; injection molding the first channel layer onto a second side of the membrane opposite the first side of the membrane such that the first channel layer is adhered to the second side of the membrane, the first channel layer defining at least a portion of the first channel; replacing the first rigid support structure with a second rigid support structure in the mold, the second rigid support structure contacting the first side of the membrane, the second rigid support structure having a shape corresponding to a second channel network including the second channel; and injection molding a second channel layer onto the first side of the membrane so as to adhere the second channel layer to the first side of the membrane, the second channel layer defining the second channel network including at least a portion of the second channel.

13. The method of claim 12, further comprising:

14. The method of claim 1 , wherein the cap component is fabricated such that the sealing lip of the cap component includes a beveled edge.

15. 1. A microfluidic device comprising: a base component defining at least a portion of a first channel of the microfluidic device; a cap component including a sealing lip extending downwardly a first distance from an upper surface side of the cap component and a support portion extending downwardly from the upper surface side of the cap component a second distance less than the first distance; and a polymeric material filling at least a portion of a cavity defined by the base component, the support portion of the cap component, and the sealing lip of the cap component, the cavity being sealed from the channel of the microfluidic device by the sealing lip of the cap component. Including, the polymeric material is injection molded to fill the cavity and harden to bond the base component to the cap component; Microfluidic devices.

16. 16. The microfluidic device of claim 15, wherein the microfluidic device comprises a second channel complementary to the first channel, the second channel being defined at least in part by the base part of the microfluidic device.

17. 17. The microfluidic device of claim 16, further comprising a semi-permeable membrane separating the first channel from the second channel.

18. 17. The microfluidic device of claim 16, further comprising a well plate formed as part of the cap component of the microfluidic device, the well plate defining at least one opening in fluid communication with the first channel or the second channel of the microfluidic device.

19. 17. The microfluidic device of claim 16, further comprising an optical layer coupled to the base part or the cap part to facilitate viewing of the microfluidic device.

20. placing a lower side of the membrane in contact with a first rigid support structure within a mold; injection molding a first channel layer onto the top side of the membrane such that the first channel layer adheres to the top side of the membrane opposite the bottom side of the membrane, the first channel layer defining a first channel network; replacing the first rigid support structure with a second rigid support structure in the mold, the second rigid support structure contacting the lower side of the membrane, the second rigid support structure having a shape corresponding to a second channel network; injection molding a second channel layer onto the lower side of the membrane such that the second channel layer adheres to the lower side of the membrane, the second channel layer defining the second channel network; providing a well plate defining at least one opening, the well plate including a sealing lip extending downwardly from a top side of the well plate a first distance and a support portion extending downwardly from the top side of the well plate a second distance less than the first distance, the sealing lip at least partially surrounding the at least one opening; placing the well plate within the mold so that the sealing lip of the well plate contacts the first channel layer and so that the at least one opening of the well plate is aligned with at least one channel of the first channel network, the first channel layer being spaced from the support portion of the well plate a third distance equal to a difference between the first distance and the second distance; injecting a polymeric material into the mold to fill at least a portion of a cavity defined by the first channel layer, the support portion of the well plate, and the sealing lip of the well plate with the polymeric material, the cavity being sealed from a channel of a microfluidic device by the sealing lip of a cap component; and curing the polymeric material to bond the well plate to the first channel layer. A method comprising:

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