Planar microfluidic triodes, devices and methods of fabrication and microfluidic circuit networks

Abstract

The application discloses a planar microfluidic transistor, a device and a preparation method and a microfluidic circuit network thereof. The planar microfluidic transistor comprises a source electrode, a drain electrode and a gate electrode; the source electrode, the drain electrode and the gate electrode form a single-layer structure; the source electrode and the drain electrode have a channel therebetween; the gate electrode comprises a deformable thin film structure, the deformable thin film structure is located on one side of the channel, and the deformable thin film structure is used for adjusting the gap of the channel to control the flow rate of fluid flowing through the channel when subjected to liquid pressure. The planar microfluidic transistor provided by the application has the source electrode, the drain electrode and the gate electrode in the same plane, so that the structure is simplified; pressure can be applied to the deformable thin film structure of the gate electrode through an adjustable pressure source, so that the fluid can be controlled; compared with a multi-layer design scheme, better portability and integration can be achieved.

Description

Technical Field

[0001] This invention relates to the field of microfluidics, and more particularly to a planar microfluidic transistor, device, fabrication method, and microfluidic circuit network. Background Technology

[0002] Microfluidic devices have wide applications in medical diagnostics and biosciences. By integrating complex laboratory procedures onto microchips, they enable efficient processing and analysis of biological samples such as blood and urine. This type of technology not only significantly accelerates reaction times but also offers automation and portability. Common forms include lab-on-a-chip and lab-on-a-disk.

[0003] Microfluidic devices primarily rely on microchannels and microvalve to control the transport, mixing, reaction, and detection of fluids. However, existing microfluidic devices typically require external pneumatic equipment and complex external piping for control, resulting in complex and bulky systems that are not conducive to miniaturization and portable applications.

[0004] To address these issues, existing solutions propose microfluidic transistors and microfluidic circuits based on multi-layer control structures. However, multi-layer fabrication solutions are limited by pneumatic drive methods, as well as the complexity of structural design, high processing costs, and long processes.

[0005] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the purpose of this invention is to provide a planar microfluidic transistor, device, fabrication method and microfluidic circuit network, so as to solve the problems of existing multilayer microfluidic transistor schemes being limited by pneumatic drive, as well as the complexity of structural design, high processing cost and long process.

[0007] The technical solution of the present invention is as follows:

[0008] In a first aspect, the present invention provides a planar microfluidic transistor, comprising: a source, a drain, and a gate; the source, the drain, and the gate constitute a single-layer structure; a channel is provided between the source and the drain; the gate includes a deformable thin film structure located on one side of the channel, the deformable thin film structure being used to adjust the gap of the channel to control the flow rate of fluid flowing through the channel when subjected to liquid pressure.

[0009] In a further embodiment of the present invention, the gate is a fan-shaped structure.

[0010] In a further embodiment of the present invention, the planar microfluidic transistor is made of polydimethylsiloxane material.

[0011] In a further embodiment of the present invention, the radian of the fan-shaped structure is 1.049–1.696.

[0012] Secondly, the present invention also provides a planar microfluidic device, which includes a substrate layer and a planar microfluidic transistor as described above, wherein the planar microfluidic transistor is bonded to the substrate layer.

[0013] In a further embodiment of the present invention, the planar microfluidic device also includes a micropump assembly connected to the planar microfluidic transistor for providing liquid pressure to the deformable thin film structure.

[0014] Thirdly, the present invention provides a planar microfluidic circuit network, comprising a plurality of microfluidic devices as described above, wherein the microfluidic devices are integrated on the same plane, and the planar microfluidic transistors are connected in series or in parallel.

[0015] Fourthly, the present invention provides a method for fabricating a microfluidic device, comprising:

[0016] Microchannel templates are constructed on silicon wafers or glass substrates using photoresist and photolithography.

[0017] Liquid polydimethylsiloxane material is poured into a microchannel template, vacuumed to remove air bubbles, and then cured.

[0018] After curing, the polydimethylsiloxane material is demolded to obtain a planar microfluidic transistor with source, drain and gate channels;

[0019] The planar microfluidic transistor's bonding surface and the corresponding substrate surface are placed in an oxygen plasma device for processing.

[0020] The planar microfluidic triode oxygen plasma device is removed, and then the area to be bonded is attached to the substrate.

[0021] Fifthly, the present invention also provides a method for fabricating a microfluidic device, comprising:

[0022] The master mold of the microfluidic transistor is printed using 3D printing equipment;

[0023] Surface treatment of the 3D printed master mold;

[0024] Liquid polydimethylsiloxane material is poured into a microchannel template, vacuumed to remove air bubbles, and then cured.

[0025] After curing, the polydimethylsiloxane material is demolded to obtain a planar microfluidic transistor with source, drain and gate channels;

[0026] The planar microfluidic transistor's bonding surface and the corresponding substrate surface are placed in an oxygen plasma device for processing.

[0027] Remove the planar microfluidic transistor oxygen plasma device and then attach the area to be bonded to the substrate layer;

[0028] or,

[0029] Imprinting molds were prepared using nanoimprinting technology;

[0030] Liquid polydimethylsiloxane material is poured into a microchannel embossing mold;

[0031] The polydimethylsiloxane material is demolded to obtain a planar microfluidic transistor with source, drain and gate channels;

[0032] The planar microfluidic transistor's bonding surface and the corresponding substrate surface are placed in an oxygen plasma device for processing.

[0033] The planar microfluidic triode oxygen plasma device is removed, and then the area to be bonded is attached to the substrate.

[0034] This invention provides a planar microfluidic transistor, device, fabrication method, and microfluidic circuit network. The planar microfluidic transistor includes a source, a drain, and a gate; the source, drain, and gate form a single-layer structure; a channel is formed between the source and drain; the gate includes a deformable thin-film structure located on one side of the channel, and the deformable thin-film structure is used to adjust the gap of the channel to control the flow rate of fluid flowing through the channel when subjected to liquid pressure. The planar microfluidic transistor provided by this invention has its source, drain, and gate on the same plane, simplifying the structure. Fluid control can be achieved by applying pressure to the deformable thin-film structure of the gate using an adjustable pressure source. Compared with multilayer designs, this provides better portability and integration, and reduces processing costs. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the overall structure of the planar microfluidic transistor in this invention.

[0037] Figure 2This is a schematic diagram of the deformable thin film of the planar microfluidic transistor in this invention in a state where it is not subjected to liquid pressure.

[0038] Figure 3 This is a schematic diagram of the deformable thin film of the planar microfluidic transistor in this invention being subjected to liquid pressure.

[0039] Figure 4 This is a graph showing the working curves of the planar microfluidic transistor in this invention at different stages.

[0040] Figure 5 This is a performance data characterization diagram of the planar microfluidic transistor in this invention.

[0041] Figure 6 This is an equivalent element diagram of the planar microfluidic transistor in this invention.

[0042] Figure 7 This is a schematic diagram of the logic microfluidic flow path that can be constructed using planar microfluidic transistors in this invention.

[0043] Figure 8 This is a schematic diagram of the microfluidic device in this invention.

[0044] Figure 9 This is a circuit diagram in one embodiment of the present invention that combines a planar microfluidic transistor network (active) with a microfluidic logic control network based on a burst valve (passive).

[0045] Figure 10 This is a schematic diagram of the process for fabricating a planar microfluidic transistor using soft photolithography in one embodiment of the present invention.

[0046] Figure 11 This is a schematic diagram of a planar microfluidic transistor fabricated using soft photolithography in one embodiment of the present invention.

[0047] Figure 12 This is a schematic diagram of the process for fabricating a planar microfluidic transistor using 3D printing in one embodiment of the present invention.

[0048] Figure 13 This is a schematic diagram of the process for fabricating a planar microfluidic transistor using nanoimprinting in one embodiment of the present invention.

[0049] The labels in the attached figure are as follows: 100, planar microfluidic transistor; 110, source; 120, drain; 130, gate; 131, deformable thin film structure; 140, channel; 200, substrate. Detailed Implementation

[0050] This invention provides a planar microfluidic transistor, device, fabrication method, and microfluidic circuit network. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0051] In the implementation methods and claims, unless otherwise specified in the text, the terms "a," "an," "the," and "the" may also include plural forms. If the embodiments of the present invention involve descriptions of "first," "second," etc., such descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features.

[0052] It should be further understood that the term "comprising" as used in this specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that when an element is referred to as "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or there may be intermediate elements present. Furthermore, "connected" or "coupled" as used herein can include wireless connections or wireless coupling. The term "and / or" as used herein includes all or any unit and all combinations of one or more associated listed items.

[0053] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0054] Furthermore, the technical solutions of the various embodiments can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0055] The inventors discovered that microfluidic devices primarily rely on microchannels and microvalves to control the transport, mixing, reaction, and detection of fluids. However, existing microfluidic devices typically require external pneumatic equipment and complex external piping for control, resulting in complex and bulky systems that are unsuitable for miniaturization and portable applications. To address these issues and reduce reliance on external control devices, existing solutions have proposed pneumatically driven microfluidic transistors and microfluidic circuits based on multi-layered control structures. However, multi-layered fabrication schemes are limited by the pneumatic drive method, structural design complexity, and manufacturing costs and processes.

[0056] To address the aforementioned technical problems, this invention provides a planar microfluidic transistor that controls the fluid flow between the source, drain, and gate via a liquid pressure signal, thereby achieving fluid amplification and switching functions. This planar design not only simplifies the system structure but also enables the microfluidic transistor to achieve efficient fluid control at lower operating pressures. It can be further integrated with portable micropumps and has subsequent expansion capabilities, making it suitable for more complex, highly integrated microfluidic systems.

[0057] Please also refer to Figures 1 to 7 The present invention provides a preferred embodiment of a planar microfluidic transistor.

[0058] In some embodiments, such as Figures 1 to 3 As shown, the present invention provides a planar microfluidic transistor 100, which includes: a source 110, a drain 120, and a gate 130; the source 110, the drain 120, and the gate 130 form a single-layer structure; a channel 140 is provided between the source 110 and the drain 120; the gate 130 includes a deformable thin film structure 131, the deformable thin film structure 131 is located on one side of the channel 140, and the deformable thin film structure 131 is used to adjust the gap of the channel 140 to control the flow rate of fluid flowing through the channel 140 when subjected to liquid pressure.

[0059] Specifically, the planar microfluidic transistor 100 has a structure similar to an electronic field-effect transistor (FET), such as... Figure 6As shown, the microfluidic transistor 100 has a drain 120, a source 110, and a gate 130, wherein the gate 130 has a deformable thin-film structure 131. When pressure is applied, fluid can flow from the source 110 to the drain 120 through a channel 140. The deformable thin-film structure 131 deforms under liquid pressure, thereby changing the gap of the channel 140 and regulating the fluid flow rate, thus enabling fluid amplification and switching functions. In other words, the pressure at the gate 130 controls the deformation of the deformable thin-film structure 131, thereby affecting the flow of fluid between the source 110 and the drain 120. When pressure is applied to the gate 130, the deformable thin-film structure 131 deforms, the channel closes, and fluid flow is blocked; when the pressure at the gate 130 decreases, the deformable thin-film structure 131 returns to its original shape, the channel opens, and fluid flows again. Thus, the operating range of this planar microfluidic transistor 100 depends on the range of liquid pressure applied to the gate 130.

[0060] The deformation principle of the thin film is as follows: The core working principle of the microfluidic planar transistor involves controlling the fluid flow between the source, drain, and gate through pneumatic pressure (controlling liquid pressure with air pressure). The applied pressure to the gate causes deformation of the vertical film, thereby regulating the opening and closing state of the fluid channel. The deformation of the thin film can be described according to thin film deformation theory, and the formula for calculating the deformation is:

[0061]

[0062] Where: ΔP represents the applied pressure difference, r is the radius of the thin film, v is the Poisson's ratio of the thin film, E is the elastic modulus of the thin film material, and t is the thickness of the thin film. By applying different pressures, the deformation of the thin film can effectively control the size and closure of the fluid channel between the source and drain electrodes, thereby realizing the fluid switching function. This thin film structure design not only simplifies the physical structure of the system, but also enables precise fluid control at relatively low operating pressures.

[0063] Shapiro Number (S-number) analysis: When analyzing fluid dynamics in aerodynamic channels, the Shapiro number measures the ratio of characteristic fluid velocity to channel wave velocity, particularly in flexible structures such as membrane-deformable channels where velocity confinement effects are significant. The formula for calculating the Shapiro number is:

[0064]

[0065] Q represents the flow rate, A is the cross-sectional area of ​​the fluid channel, E (Young's modulus) and T (film thickness) are parameters of the film used to describe its structural characteristics, ρ is the fluid density, and H is the geometric height of the channel. When S > 1, it indicates that the velocity limiting effect caused by cavity deformation is enhanced, and the dynamic deformation of the film further regulates the fluid flow velocity. In planar microfluidic transistors, the deformation of the deformable film structure not only regulates the opening and closing of the fluid channel but also affects the flow velocity, enabling the device to precisely control the fluid movement under different pressure conditions. Combining film deformation theory and Shapiro number analysis, planar microfluidic transistors achieve efficient fluid control functions through flexible pressure control.

[0066] like Figure 4 As shown, Figure 4 This indicates the flow trend of the drain flow rate before and after the gate voltage reaches the pinch-off point voltage. Figure 5 In the figure, 'a' represents the relationship between source pressure and drain flow rate. Figure 5 In the figure, b represents the relationship between gate pressure and drain flow rate. When the source pressure increases, the flow rate between the source and drain gradually approaches saturation. When the gate pressure gradually increases, the flow rate between the source and drain gradually decreases. It can be seen that by controlling the liquid pressure of the gate, the flow rate of the fluid in the channel of the planar microfluidic transistor can be controlled.

[0067] As can be seen, the planar microfluidic transistor provided by this invention has its source, drain, and gate on the same plane, simplifying the structure. Fluid control can be achieved by applying pressure to the deformable thin film structure of the gate through an adjustable pressure source. By combining this planar microfluidic transistor into a logic flow path, precise control can be provided for complex liquid handling, and portability and integration can be improved, while reducing manufacturing costs. It is particularly suitable for applications requiring lightweight and rapid operation, such as biomedical analysis and portable chemical detection.

[0068] For example, Figure 6 This is an equivalent circuit diagram of a planar microfluidic transistor. Based on the basic component structure of planar microfluidic transistors, more complex fluid logic circuits can be constructed. These logic circuits can achieve logic functions similar to electronic circuits, such as... Figure 7 As shown, for example, Figure 7 The inverter in a Figure 7 AND, OR, and NOT logic gates in b Figure 7 Fluid controller in c and Figure 7The oscillator in d. The principle of implementing an inverter is as follows: by connecting two microfluidic transistors in series, a fluid inverter can be constructed. The input of the inverter is a pneumatic pressure signal. When the input signal is "high" (i.e., high pressure), the output channel is closed; when the input signal is "low," the output channel is open, achieving inverted output. The principle of implementing AND / OR / NOT logic gates is as follows: by combining multiple microfluidic transistors, AND, OR, and NOT logic operations can be implemented. For an AND gate, the gates of multiple transistors are controlled simultaneously; the output channel is only opened when all input signals are "high." For an OR gate, the output is opened as long as any one input signal is "high." The NOT gate is implemented using an inverter. The principle of implementing a fluid controller is as follows: the fluid controller is composed of microfluidic transistors and flow resistors, enabling a relatively stable output flow rate when the input pressure fluctuates. Fluid controllers have important applications in biomedicine and chemical synthesis. By adjusting pneumatic pressure, complex fluid processing operations, such as automated mixing, separation, and reaction, can be achieved. The principle of realizing the oscillator is that by constructing a feedback loop with multiple microfluidic transistors, a periodic fluid oscillation signal can be generated.

[0069] Taking the application of planar microfluidic transistor-based oscillators in automated cell culture as an example: certain cell types (such as cardiomyocytes and vascular endothelial cells) require a dynamic pressure-changing environment during in vitro culture to simulate their in vivo growth conditions. However, traditional culture methods struggle to provide this periodically changing environment. Oscillators composed of planar microfluidic transistors can generate fluid oscillations with specific waveforms, creating a periodically changing flow velocity environment and providing cells with a periodically varying pressure environment. This dynamic pressure simulation effectively promotes cell growth and functionalization. In practice, the oscillator uses multiple transistors to form a feedback loop, generating a stable oscillation waveform. Integrating this oscillator into a cell culture system can provide a dynamic pressure-changing environment for cells, suitable for automated cell culture, especially for cells sensitive to dynamic pressure, such as cardiomyocytes and vascular endothelial cells. Researchers can then control the oscillation frequency and amplitude, providing customized culture conditions for different cell types, improving culture efficiency and reducing human interference.

[0070] In some embodiments, the planar microfluidic transistor 100 is made of polydimethylsiloxane (PDMS) material.

[0071] Specifically, the planar microfluidic transistor 100 can be integrally formed using PDMS material. In this way, the deformable thin film structure 131 is a PDMS thin film, which is elastic and can deform when subjected to liquid pressure to reduce the size of the channel 140. When the liquid pressure disappears, the PDMS thin film can return to its initial state, thereby realizing the opening and closing of the channel 140.

[0072] The thickness and elastic modulus of the deformable thin film structure 131 affect its deformation capability. The thinner the film, the shorter the deformation response time; the thicker the film, the longer the deformation response time. At the same time, the film deformation is more stable, making it suitable for high-precision fluid control.

[0073] In some embodiments, the width H (i.e., thickness) of the deformable thin film structure 131 is 10-20 mm, for example, 10 mm, 15 mm, or 20 mm; the height W2 is 100-300 mm, for example, 100 mm, 200 mm, or 300 mm; and the length L is 300-800 mm, for example, 300 mm, 500 mm, or 800 mm. In one implementation, the deformable thin film structure 131 may be a PDMS thin film with a thickness of 10 mm, a height of 100 mm, and a length of 300 mm.

[0074] Furthermore, such as Figures 1 to 3 As shown, the gate 130 has a fan-shaped structure. Specifically, the gate 130 has an internal fan-shaped structure to achieve more stable interlayer bonding. Because the planar microfluidic transistor 100 adopts an integrated planar design, the gate 130 can effectively control the flow between the source 110 and the drain 120 under a liquid pressure of 30-60 kPa. In some embodiments, the arc of the fan-shaped structure is 1.049-1.696, for example, 1.049, 1.530, 1.696, etc. The dimensions of the planar microfluidic transistor 100 (i.e., the dimensions of the deformable thin film structure 131 and the width W1 of the channel 140) and the material affect the response speed, sensitivity, and overall performance (including transconductance, impedance, gain, on / off ratio, etc.) of the planar microfluidic transistor 100. By adjusting the geometry of the intermediate channel, fluid switching control can be achieved with smaller deformation, thereby accelerating the arrival of saturation. The optimized geometry of the microfluidic channel allows for more precise matching of membrane deformation caused by pressure at the gate 130 with changes in the flow channel, thereby improving the accuracy and response speed of the fluid switch. Furthermore, the planar design allows for future expansion, enabling integration into more complex microfluidic circuits, such as by stacking multiple layers of fluid channels to achieve the integration of more functional modules.

[0075] In some embodiments, such as Figure 8As shown, the present invention also provides a planar microfluidic device, which includes a substrate layer 200 and a planar microfluidic transistor 100 as described above, wherein the planar microfluidic transistor 100 is bonded to the substrate layer 200. In this embodiment, the planar microfluidic transistor 100 and the substrate layer 200 are bonded together, and the device is obtained by sealing the planar microfluidic transistor 100 with the substrate layer 200.

[0076] In some embodiments, the planar microfluidic device further includes a micropump assembly connected to the planar microfluidic transistor 100 for providing liquid pressure to the deformable thin film structure 131.

[0077] In this embodiment, the micropump assembly can provide precise hydraulic pressure to regulate the deformation degree of the deformable thin film structure 131, thereby achieving precise control of fluid transmission and output without relying on external traditional starting devices. In one implementation, the micropump assembly can be controlled via Bluetooth, enabling remote and precise control of fluid flow rate, meeting portability requirements and expanding the application areas of microfluidic devices. The specific structure of the micropump assembly in this embodiment is detailed in patent CN201710923269.0 and will not be repeated here.

[0078] In some embodiments, the present invention provides a planar microfluidic circuit network, including a plurality of microfluidic devices as described above, wherein the microfluidic devices are integrated on the same plane, and the planar microfluidic transistors are connected in series or in parallel.

[0079] Specifically, the planar microfluidic transistor features a single-layer patterned superimposed sealing layer (i.e., base layer) design, enabling the construction of complex microfluidic circuit networks, such as multi-channel liquid transport, automated sample processing, and dynamic liquid dispensing. By integrating multiple planar microfluidic transistors into a single planar structure, multi-level series or parallel fluid logic operations, fluid signal processing, and dynamic adjustment of fluid transport paths can be achieved. Furthermore, it can be combined with portable micropumps for widespread application in biomedical analysis, such as high-throughput multi-sample detection, automated cell culture, liquid dilution, and precise control during reaction processes; in the field of chemical reactions, it enables complex multi-step chemical synthesis and online analysis, ensuring efficient and accurate operation.

[0080] In some embodiments, such as Figure 9As shown, a planar microfluidic transistor network (active) can also be combined with a microfluidic logic control network based on a burst valve (passive) to further enhance the system's control accuracy and logic function. Here, the power supply represents the capillary burst valve, which has a certain fluid blocking effect and will only allow fluid to pass through after reaching the threshold pressure P. The square represents the flow resistance, which is composed of flow channels. The capacitor represents the cavity, which has the ability to store fluid. The transistor corresponds to the microfluidic transistor.

[0081] In this embodiment, the burst valve controls fluid flow through a preset pressure threshold, enabling it to automatically open or close under specific conditions. This combines active and passive control schemes to adapt to a wider range of application scenarios and needs. In this embodiment, the microfluidic transistor network serves as the main fluid control unit, regulating fluid transmission and switching states via its gate, while the burst valve network provides an additional logic control layer. Specifically, the burst valve's threshold can be set to different pressure values ​​to implement AND, OR, NOT, and other logical functions. For example, the microfluidic transistor can be used for basic fluid on / off control, while the burst valve can act as a switching node for fluid signals under specific pressure conditions, thereby enabling multi-level logic operations.

[0082] Applications of this solution include multi-step chemical reactions, automated sample dilution, and dynamic adjustment of fluid paths. By combining microfluidic transistors with the logic control of burst valves, more complex and automated microfluidic circuit networks can be designed. This not only achieves precise fluid transport control but also executes preset logic conditions within the system, further expanding the application scope of this invention. This combination of structures also provides stronger control capabilities and application flexibility for high-throughput biological detection, rapid on-site analysis, and multi-stage chemical reactions.

[0083] In some embodiments, such as Figure 10 As shown, the present invention provides a method for fabricating a microfluidic device, which includes the following steps:

[0084] S100: Microchannel templates are constructed on silicon wafers or glass substrates using photoresist and photolithography.

[0085] S200. Pour liquid polydimethylsiloxane material into a microchannel template, remove air bubbles by vacuuming, and then perform curing treatment.

[0086] After curing S300, the polydimethylsiloxane material is demolded to obtain a planar microfluidic transistor with source, drain and gate channels;

[0087] S400: Place the plane of the planar microfluidic transistor to be bonded and the corresponding plane of the substrate layer in an oxygen plasma device for processing;

[0088] S500: Remove the planar microfluidic transistor oxygen plasma device and then attach the area to be bonded to the substrate.

[0089] In this embodiment, soft lithography is first used to construct a microchannel template on a silicon wafer or glass substrate using photoresist (taking SU-8 photoresist as an example). This process specifically includes SU-8 photoresist spin coating, L-Line light source exposure, and development. Figure 11 As shown in the diagram, liquid PDMS is then poured into a microchannel template, and air bubbles are removed by vacuuming, followed by curing. After the liquid PDMS has cured, it is demolded to obtain a microfluidic transistor structure with source, drain, and gate channels. The planar microfluidic transistor's bonding surface and the corresponding substrate surface are then placed in an oxygen plasma device for an appropriate time. The planar microfluidic transistor is then removed from the oxygen plasma device, and finally, the bonding area is attached to the substrate. After a certain time, the functional layer (planar microfluidic transistor) is bonded to the substrate, resulting in a microfluidic device.

[0090] In some embodiments, such as Figure 12 As shown, the present invention also provides another method for fabricating a microfluidic device, which includes the following steps:

[0091] S100, Printing the master mold of the microfluidic transistor using 3D printing equipment;

[0092] S200, Surface treatment of the 3D printed master mold;

[0093] S300. Pour liquid polydimethylsiloxane material into a microchannel template, remove air bubbles by vacuuming, and then perform curing treatment.

[0094] After curing S400, the polydimethylsiloxane material is demolded to obtain a planar microfluidic transistor with source, drain and gate channels;

[0095] S500: Place the bonding surfaces of the planar microfluidic transistor and the corresponding substrate surfaces inside an oxygen plasma device for processing.

[0096] S600: Remove the planar microfluidic transistor oxygen plasma device and then attach the area to be bonded to the substrate.

[0097] In this embodiment, a master mold for the microfluidic transistor is first printed using a 3D printing device. The printing material can be high-resolution resin or photosensitive material. After printing the master mold, its surface is treated to ensure a smooth surface and reduce PDMS adhesion during demolding. Liquid PDMS is then poured into a microchannel template, vacuumed to remove air bubbles, and cured. After curing, the PDMS is demolded to obtain a planar microfluidic transistor with source, drain, and gate channels. The bonding surfaces of the planar microfluidic transistor and the corresponding substrate surfaces are placed in an oxygen plasma device for a certain period. The oxygen plasma device is then removed, and the bonding areas are attached to the substrate. After a certain time, bonding is completed, resulting in the microfluidic device.

[0098] In some embodiments, such as Figure 13 As shown, the present invention also provides another method for fabricating a microfluidic device, which includes the following steps:

[0099] S100, Imprinting molds are prepared using nanoimprinting technology;

[0100] S200. Pour the liquid polydimethylsiloxane material into the microchannel embossing mold;

[0101] S300. Demold the polydimethylsiloxane material to obtain a planar microfluidic transistor with source, drain and gate channels;

[0102] S400: Place the plane of the planar microfluidic transistor to be bonded and the corresponding plane of the substrate layer in an oxygen plasma device for processing;

[0103] S500: Remove the planar microfluidic transistor oxygen plasma device and then attach the area to be bonded to the substrate.

[0104] In this embodiment, an imprinting mold is first prepared using nanoimprinting technology. Liquid PDMS is poured into the microchannel imprinting mold under appropriate temperature and pressure. After the mold cools, the PDMS is demolded to obtain a planar microfluidic transistor with source, drain, and gate channels. The bonding surfaces of the planar microfluidic transistor and the corresponding substrate surfaces are placed in an oxygen plasma device for a certain period of time. After the oxygen plasma device is removed, the bonding areas are then attached to the substrate. After a certain period of time, bonding is completed, and the microfluidic device is obtained.

[0105] In summary, the planar microfluidic transistor, device, fabrication method, and microfluidic circuit network provided by this invention have the following beneficial effects:

[0106] By controlling the fluid flow between the source, drain, and gate using a liquid pressure signal, fluid amplification and switching functions are achieved. This planar design not only simplifies the system structure but also enables efficient fluid control of the microfluidic transistor at lower operating pressures. It can be further integrated with portable micropumps and has subsequent expansion capabilities, making it suitable for more complex and highly integrated microfluidic systems.

[0107] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A planar microfluidic transistor, characterized in that, include: Source, drain, and gate; The source, the drain, and the gate form a single-layer structure; a channel is provided between the source and the drain; the gate includes a deformable thin film structure located on one side of the channel, and the deformable thin film structure is used to adjust the gap of the channel to control the flow rate of fluid flowing through the channel when subjected to liquid pressure. The gate is a fan-shaped structure; the arc of the fan-shaped structure is 1.049-1.696; the thickness of the deformable thin film structure is 10-20 mm, and the height is 100-300 mm; The planar microfluidic transistor is integrally molded.

2. The planar microfluidic transistor according to claim 1, characterized in that, The planar microfluidic transistor is made of polydimethylsiloxane.

3. A planar microfluidic device, characterized in that, It includes a substrate layer and a planar microfluidic transistor as described in any one of claims 1-2, wherein the planar microfluidic transistor is bonded to the substrate layer.

4. The planar microfluidic device according to claim 3, characterized in that, It also includes a micropump assembly connected to the planar microfluidic transistor for providing liquid pressure to the deformable thin film structure.

5. A microfluidic circuit network, comprising a plurality of microfluidic devices as described in claim 3 or 4, characterized in that, The microfluidic devices are integrated on the same plane, and the planar microfluidic transistors are connected in series or in parallel.

6. A method for fabricating a planar microfluidic device as described in claim 3, characterized in that, include: Microchannel templates are constructed on silicon wafers or glass substrates using photoresist and photolithography. Liquid polydimethylsiloxane material is poured into a microchannel template, vacuumed to remove air bubbles, and then cured. After curing, the polydimethylsiloxane material is demolded to obtain a planar microfluidic transistor with source, drain and gate channels; The planar microfluidic transistor's bonding surface and the corresponding substrate surface are placed in an oxygen plasma device for processing. The planar microfluidic triode oxygen plasma device is removed, and then the area to be bonded is attached to the substrate.

7. A method for fabricating a planar microfluidic device as described in claim 3, characterized in that, include: The master mold of the microfluidic transistor is printed using 3D printing equipment; Surface treatment of the 3D printed master mold; Liquid polydimethylsiloxane material is poured into a microchannel template, vacuumed to remove air bubbles, and then cured. After curing, the polydimethylsiloxane material is demolded to obtain a planar microfluidic transistor with source, drain and gate channels; The planar microfluidic transistor's bonding surface and the corresponding substrate surface are placed in an oxygen plasma device for processing. Remove the planar microfluidic transistor oxygen plasma device and then attach the area to be bonded to the substrate layer; or, Imprinting molds were prepared using nanoimprinting technology; Liquid polydimethylsiloxane material is poured into a microchannel imprinting mold; The polydimethylsiloxane material was demolded to obtain a planar microfluidic transistor with source, drain and gate channels; The planar microfluidic transistor's bonding surface and the corresponding substrate surface are placed in an oxygen plasma device for processing. The planar microfluidic triode oxygen plasma device is removed, and then the area to be bonded is attached to the substrate.

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