Micro-channel pressure sensor based on coplanar copper electrode resistance change

Abstract

The present application relates to the technical field of microfluidics, and specifically relates to a micro-channel pressure sensor based on coplanar copper electrode resistance change, comprising: an outer frame, a rigid microfluidic chip, a coplanar copper electrode pair, and a coplanar copper electrode substrate, the coplanar copper electrode substrate is arranged in the outer frame, the coplanar copper electrode pair is arranged on the coplanar copper electrode substrate, and the rigid microfluidic chip is arranged on the coplanar copper electrode substrate; the rigid microfluidic chip comprises an aqueous phase inlet and a measuring blind end channel, an oil phase inlet, a droplet outlet, a droplet outlet channel, an oil phase inlet channel, a T-shaped intersection, a to-be-measured channel, and an aqueous phase inlet channel, the aqueous phase inlet is arranged at one end of the aqueous phase inlet channel, and the oil phase inlet is arranged at one end of the oil phase inlet channel. The micro-channel pressure sensor has the advantages of miniaturization, high sensitivity, easy integration into a T-shaped droplet generation chip, and is of great significance for promoting the application of microfluidic technology and its wide promotion in scientific research and practical application.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of microfluidic technology, and particularly relates to a micro-channel pressure sensor based on resistance change of coplanar copper electrodes. BACKGROUND

[0002] With the continuous progress of microfluidic technology, lab-on-a-chip and micro total analysis systems (μTAS) have been widely applied in various fields, including clinical diagnosis, cell biology research, tumor cell detection, biochemical analysis, and DNA analysis. These applications all involve precise control and analysis of extremely small volumes of liquid or cells, and microfluidic technology is therefore hailed as a key scientific technology for controlling and manipulating microfluids and particles at the microscale.

[0003] T-shaped droplet generation chip is used for droplet generation, which is a common droplet formation technology in microfluidic technology. It is mainly used for manipulating and dispersing small droplets. The basic principle of the T-shaped droplet generation chip is to combine two micron-scale channels, namely the water phase channel and the oil phase channel, to form a T-shaped intersection structure at the intersection of the channels. The surface tension and dynamic effects of the fluid are used to form a stable droplet at the T-shaped droplet intersection.

[0004] In the T-shaped droplet generation chip, accurate measurement of pressure distribution is not only the basis for understanding the characteristics of fluid flow, but also the key to optimizing the design of the T-shaped droplet generation chip. Precise pressure measurement can significantly improve the ability of microfluidic systems to handle complex fluid samples, thereby optimizing the results of biomedical experiments, chemical analysis and other applications, ensuring the repeatability and reliability of experimental data. Accurate control of pressure also helps to standardize microfluidic systems in the design and experimental stages, promoting wider technological development and application expansion.

[0005] However, existing capacitive, piezoelectric and optical pressure sensing technologies face a number of challenges in the T-shaped droplet generation chip, such as large size, slow response speed and difficulty in integration with the T-shaped droplet generation chip. The size of these sensors is usually large, making it difficult to embed them into the micro-sized chip flow channel structure, affecting the miniaturization and functional complexity of the overall device. Their low response speed and sensitivity also make it difficult to meet the needs of rapidly changing microfluidic environments, resulting in insufficient accuracy and real-time data. These limitations slow down the development of microfluidic technology in high-precision biomedical research and commercial applications. SUMMARY

[0006] Therefore, the technical problem to be solved by the present application is to overcome the problem that the size of the sensor in the prior art is usually large, making it difficult to embed it into the micro-sized chip flow channel structure, affecting the miniaturization and functional complexity of the overall device, thereby providing a micro-channel pressure sensor based on resistance change of coplanar copper electrodes.

[0007] To solve the above technical problems, the application provides a micro-channel pressure sensor based on coplanar copper electrode resistance change, comprising: an outer frame and a rigid microfluidic chip, a coplanar copper electrode pair, and a coplanar copper electrode substrate, wherein the coplanar copper electrode substrate is arranged in the outer frame, the coplanar copper electrode pair is arranged on the coplanar copper electrode substrate, and the rigid microfluidic chip is arranged on the coplanar copper electrode substrate; the rigid microfluidic chip comprises a water phase inlet and a measuring blind end channel, an oil phase inlet, a droplet outlet, a droplet outlet channel, an oil phase inlet channel, a T-shaped intersection, a to-be-measured channel, and a water phase inlet channel, the water phase inlet is arranged at one end of the water phase inlet channel, the oil phase inlet is arranged at one end of the oil phase inlet channel, the droplet outlet is arranged at one end of the droplet outlet channel, the water phase inlet channel, the measuring blind end channel, the oil phase inlet channel, and the droplet outlet channel are arranged in parallel and are in communication with the to-be-measured channel, and the intersection of the oil phase inlet channel and the to-be-measured channel is the T-shaped intersection.

[0008] Further, the water phase inlet channel, the measuring blind end channel, the oil phase inlet channel, and the droplet outlet channel are arranged in parallel.

[0009] Further, the water phase inlet channel, the measuring blind end channel, the oil phase inlet channel, and the droplet outlet channel are perpendicular to the to-be-measured channel.

[0010] Further, the measuring blind end channel has a length of 20 mm, a width of 1.5 mm, and a height of 500 μm.

[0011] Further, the water phase inlet and the droplet outlet are circular openings with a diameter of 1.1 mm.

[0012] Further, the coplanar copper electrode pair comprises a first pad and a second pad, a first measuring area, and a second measuring area, the first pad is connected with the first measuring area, and the second pad is connected with the second measuring area.

[0013] Further, the first measuring area and the second measuring area each have a width of 300 μm, and the spacing between the first measuring area and the second measuring area is 300 μm.

[0014] Further, the first measuring area and the second measuring area are arranged in parallel with the measuring blind end channel and are centrally aligned.

[0015] Further, the coplanar copper electrode substrate comprises a float glass, an ultrathin double-sided adhesive tape, and UV glue, the float glass is used as a substrate for etching the coplanar copper electrode pair, the ultrathin double-sided adhesive tape is used to connect the rigid microfluidic chip and the coplanar copper electrode substrate, and the UV glue is used to connect the coplanar copper electrode pair and the float glass.

[0016] Further, the outer frame comprises an adhesion area for adhering the coplanar copper electrode substrate, and a wire through hole through which a wire passes and connects with the coplanar copper electrode pair.

[0017] The technical scheme of the present application has the following advantages:

[0018] The micro-channel pressure sensor based on the resistance change of the coplanar copper electrode provided by the present application comprises an outer frame, a rigid micro-fluidic chip, a coplanar copper electrode pair, and a coplanar copper electrode substrate, wherein the coplanar copper electrode substrate is arranged in the outer frame, the coplanar copper electrode pair is arranged on the coplanar copper electrode substrate, and the rigid micro-fluidic chip is arranged on the coplanar copper electrode substrate.

[0019] The micro-channel pressure sensor is formed by arranging the outer frame, the rigid micro-fluidic chip, the coplanar copper electrode pair, and the coplanar copper electrode substrate. The water phase inlet is used for injecting a dispersed phase for droplet generation, the oil phase inlet is used for injecting a continuous phase for droplet generation, and the droplet outlet is used for collecting the droplets generated by the T-type method. The measured channel is a position where fluid pressure needs to be measured, and the measured channel is part of the water inlet phase channel and is used for measuring the fluid pressure change of the water phase. The measurement blind end channel is a channel with only an inlet and no outlet and is perpendicular to the measured channel. The T-type intersection is the intersection of the water phase and the oil phase and is the position of the droplet generation by the T-type method. The micro-channel pressure sensor has the advantages of miniaturization, high sensitivity, and easy integration into a T-type droplet generation chip.

[0020] The summary section is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the specific embodiments of the present application or the prior art, the accompanying drawings needed to be used in the description of the specific embodiments or the prior art will be briefly introduced. Obviously, the accompanying drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0022] Figure 1 Structure schematic diagram of the micro-channel pressure sensor based on the resistance change of the coplanar copper electrode provided by the present application;

[0023] Figure 2 Structure schematic diagram of the outer frame of the micro-channel pressure sensor based on the resistance change of the coplanar copper electrode provided by the present application;

[0024] Figure 3 Structure schematic diagram of the rigid micro-fluidic chip of the micro-channel pressure sensor based on the resistance change of the coplanar copper electrode provided by the present application;

[0025] Figure 4 Structure schematic diagram of the coplanar copper electrode pair of the micro-channel pressure sensor based on the resistance change of the coplanar copper electrode provided by the present application;

[0026] Figure 5 Cross-sectional view of the micro-channel pressure sensor based on the resistance change of the coplanar copper electrode provided by the present application;

[0027] Figure 6 Measurement principle schematic diagram of the micro-channel pressure sensor based on the resistance change of the coplanar copper electrode provided by the present application.

[0028] Explanation of reference signs:

[0029] 1, outer frame; 101, coplanar copper electrode substrate adhesion area; 102, coplanar copper electrode external lead hole;

[0030] 2, rigid micro-fluidic chip; 201, water phase inlet; 202, measurement blind end channel; 203, oil phase inlet; 204, droplet outlet; 205, droplet outlet channel; 206, oil phase inlet channel; 207, T-shaped intersection; 208, channel to be measured; 209, water phase inlet channel;

[0031] 3, coplanar copper electrode pair; 301, first measurement area; 302, first solder pad; 303, second solder pad; 304, second measurement area;

[0032] 4, coplanar copper electrode substrate; 401, float glass; 402, ultra-thin double-sided adhesive tape; 403, UV glue. DETAILED DESCRIPTION

[0033] In the following certain exemplary embodiments are simply described. As will be realized by those skilled in the art, the described embodiments can be modified in various different ways without departing from the spirit or scope thereof. Accordingly, the drawings and descriptions are to be regarded as illustrative in nature rather than restrictive.

[0034] In the description of the disclosure, it needs to be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "straight", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, which are only for the purpose of facilitating the description of the disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the disclosure. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the disclosure, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified and limited.

[0035] In the description of the disclosure, it needs to be understood that, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection or can communicate with each other; it can be directly connected, or indirectly connected through intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the disclosure can be understood according to the specific circumstances.

[0036] In the disclosure, unless otherwise explicitly specified and limited, the first feature "on" or "under" the second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the first feature "on", "above" and "on" the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "under", "below" and "under" the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0037] The disclosure provided below provides many different embodiments or examples for implementing different structures of the disclosure. In order to simplify the disclosure of the disclosure, the components and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the disclosure. In addition, the disclosure can repeatedly refer to numbers and / or letters in different examples, and such repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the disclosure provides examples of various specific processes and materials, but those of ordinary skill in the art can realize the application of other processes and / or the use of other materials.

[0038] The preferred embodiments of the disclosure are described below in conjunction with the accompanying drawings, and it should be understood that the preferred embodiments described herein are only used to illustrate and explain the disclosure, and are not intended to limit the disclosure.

[0039] Please refer to Figures 1 to 6 As shown in the drawings, the present application provides a micro-channel pressure sensor based on the resistance change of coplanar copper electrodes, comprising: an outer frame 1 and a rigid microfluidic chip 2, a pair of coplanar copper electrodes 3, and a coplanar copper electrode substrate 4, the coplanar copper electrode substrate 4 is arranged in the outer frame 1, the coplanar copper electrode pair 3 is arranged on the coplanar copper electrode substrate 4, and the rigid microfluidic chip 2 is arranged on the coplanar copper electrode substrate 4; the rigid microfluidic chip 2 comprises a water phase inlet 201 and a measurement blind end channel 202, an oil phase inlet 203, a droplet outlet 204, a droplet outlet channel 205, an oil phase inlet channel 206, a T-shaped intersection 207, a to-be-measured channel 208, and a water phase inlet channel 209, the water phase inlet 201 is arranged at one end of the water phase inlet channel 209, the oil phase inlet 203 is arranged at one end of the oil phase inlet channel 206, the droplet outlet 204 is arranged at one end of the droplet outlet channel 205, the water phase inlet channel 209, the measurement blind end channel 202, the oil phase inlet channel 206, and the droplet outlet channel 205 are arranged at intervals, and all communicate with the to-be-measured channel 208, and the intersection of the oil phase inlet channel 206 and the to-be-measured channel 208 is the T-shaped intersection 207.

[0040] The micro-channel pressure sensor is composed of the outer frame 1, the rigid microfluidic chip 2, the coplanar copper electrode pair 3 and the coplanar copper electrode substrate 4. The water phase inlet 201 is used for injecting the dispersed phase for droplet generation, the oil phase inlet 203 is used for injecting the continuous phase for droplet generation, and the droplet outlet 204 is used for collecting the droplets generated by the T-type method. The to-be-measured channel 208 is a position where the fluid pressure needs to be measured, and the to-be-measured channel 208 is a part of the water phase inlet channel 209 and is used for measuring the fluid pressure change of the water phase. The measurement blind end channel 202 is a channel with only an inlet and no outlet and is perpendicular to the to-be-measured channel 208. The measurement blind end channel 202 is centrally aligned with the coplanar copper electrode, the water phase fluid extrudes the gas in the measurement blind end channel 202, and causes the resistance of the coplanar copper electrode to change. The T-type intersection 207 is the intersection of the water phase and the oil phase, and is the position of the T-type droplet generation.

[0041] The micro-channel pressure sensor has the advantages of miniaturization, high sensitivity and easy integration into a T-type droplet generation chip, and is a new type of micro-channel pressure sensor. The micro-channel pressure sensor has important significance for promoting the application of microfluidic technology and its wide promotion in scientific research and practical application. The sensor should be able to realize high-precision pressure measurement, and at the same time be compatible with the existing microfluidic platform to support complex biological analysis and chemical analysis experiments.

[0042] Under the joint action of fluid dynamics and interfacial tension, when the liquid flows through the measurement blind end channel 202, it enters the measurement blind end channel 202 and extrudes the gas in the measurement blind end channel 202 until the gas pressure and the liquid pressure are equal. The movement of the liquid surface in the measurement blind end channel 202 causes the resistance of the coplanar copper electrode pair 3 to change.

[0043] When the fluid flows through the measurement blind end channel 202, it enters the measurement blind end channel 202 and compresses the measurement blind end gas until the gas pressure P1 and the liquid pressure Pliquid are equal. At this time, the gas-liquid interface of the measurement blind end channel 202 moves a distance h. Since the cross-sectional area S of the measurement blind end is fixed at 0.75 mm2 and the length H of the measurement blind end channel 202 is fixed at 20 mm, the volume V1 of the compressed gas in the measurement blind end channel 202 is calculated by formula (1-1), and the volume V2 of the uncompressed gas is calculated by formula (1-2). Formula (1-3) is the gas state equation, where n is the amount of substance of the blind end gas. Since the rigid microfluidic chip 2 used has good airtightness, the amount of substance n of the gas will not change when the gas is compressed. R is a constant.

[0044] V1=S(H-h) (1-1)

[0045] V0=SH (1-2)

[0046] PV=nRT (1-3)

[0047] When the gas is compressed, the temperature is T1, and the state equation of the compressed gas is as shown in formula (1-4). The state equation of the gas when it is not compressed is as shown in formula (1-5), and formula (1-4) and (1-5) can be combined to obtain the compressed gas pressure calculation formula (1-6).

[0048] P1V1 = P1S (H - h) = nRT1 (1-4)

[0049] P0V0 = P0SH = nRT0 (1-5)

[0050]

[0051] In the experiment, the temperature change is very small and can be ignored, so the liquid Pliquid pressure calculation formula (1-7) is obtained.

[0052]

[0053] Further discuss the relationship between the coplanar copper electrode resistance R and the gas-liquid interface moving distance h, and finally obtain the expression of Pliquid about R. The short-circuit resistance of the coplanar copper electrode to 3 is 3.8Ω, and the resistance of this part is ignored.

[0054] The present application adopts Schwarz-Christoffel transformation to map the coplanar electrode into a resistance equivalent out-of-plane electrode, the equivalent width of the electrode is as shown in formula (1-8), the equivalent spacing between the electrodes is as shown in formula (1-9), and the water phase is used as the medium between the out-of-plane electrodes. In the formula, K(x) represents the first kind of elliptic function, d represents the width of the coplanar copper electrode 300 microns, w represents the distance between the coplanar copper electrodes 300 microns, ρliquid represents the water phase resistivity, and Gliquid represents the water phase conductivity.

[0055] The formula (1-8), (1-9) and (1-10) are combined to obtain the calculation expression (1-11) of the coplanar copper electrode resistance R.

[0056]

[0057] Further combining formula (1-7) with formula (1-11) can obtain the final pressure calculation formula (1-12).

[0058]

[0059] The coplanar copper electrode width d = 300 microns, the distance w = 300 microns, the water phase conductivity Gliquid = 2.3 mS / cm, and the fluid pressure calculation formula (1-13) under this condition can be obtained by substituting formula (1-12).

[0060]

[0061] Therefore, as long as we measure the resistance R of the coplanar copper electrode pair 3 when the fluid flows through the measuring channel, we can calculate the fluid pressure Pliquid (unit: KPa) by entering formula (1-12).

[0062] In some alternative embodiments, the aqueous phase inlet channel 209 and the measuring blind end channel 202, the oil phase inlet channel 206, and the droplet outlet channel 205 are arranged in parallel. And the aqueous phase inlet channel 209 and the measuring blind end channel 202, the oil phase inlet channel 206, and the droplet outlet channel 205 are perpendicular to the to-be-measured channel 208.

[0063] The measuring blind end channel 202 and the oil phase inlet channel 206 are located in the middle of the aqueous phase inlet channel 209 and the droplet outlet 204, and the measuring blind end channel 202 is a rectangular cavity with a length of 20 mm, a width of 1.5 mm, a height of 500 μm, and only an inlet without an outlet.

[0064] Looking down at the rigid microfluidic chip 2, the aqueous phase inlet 201 and the droplet outlet 204 are circular ports with a diameter of 1.1 mm.

[0065] The aqueous phase inlet 201 extends into the rigid microfluidic chip 2 to form an aqueous phase inlet channel 209 with a length of 20 mm, a width of 1 mm, and a height of 500 μm, which is connected to the measuring blind end channel 202 inlet through the horizontal to-be-measured channel, and the measuring blind end channel 202 and the to-be-measured channel 208 are further extended to be connected to the T-shaped intersection 207, the to-be-measured channel 208 serves as the aqueous phase channel at the T-shaped intersection 207, and the oil phase inlet 203 is above the T-shaped intersection 207, which extends into the rigid microfluidic chip 2 to form an oil phase inlet channel 206, which is connected to the T-shaped intersection 207, and the oil phase inlet channel 206 serves as the oil phase channel at the T-shaped intersection 207, and the T-shaped intersection 207 is further extended to the right to be connected to the droplet outlet channel 205 extending into the outlet channel of the rigid microfluidic chip 2. The two inlet channels, the outlet channel, and the blind end channel are all vertically oriented, and the blind end to-be-measured channel 208 is horizontally oriented.

[0066] Among them, the coplanar copper electrode pair 3 includes a first pad 302 and a second pad 303, a first measurement region 301, and a second measurement region 304, the first pad 302 is connected to the first measurement region 301, and the second pad 303 is connected to the second measurement region 304.

[0067] The width of the first measurement region 301 and the second measurement region 304 is 300 μm, and the spacing between the first measurement region 301 and the second measurement region 304 is 300 μm.

[0068] Specifically, the first measurement area 301 and the second measurement area are arranged in parallel with the measurement blind channel 202 and are centrally aligned. The first common pad and the second pad 303 are exposed outside the epoxy resin channel and are used to connect external circuits.

[0069] In some optional embodiments, the coplanar copper electrode substrate 4 comprises a float glass 401, an ultra-thin double-sided adhesive tape 402, and a UV glue 403. The float glass 401 is used as a substrate for etching the coplanar copper electrode pair 3. The ultra-thin double-sided adhesive tape 402 is used to connect the rigid microfluidic chip 2 and the coplanar copper electrode substrate 4. The UV glue 403 is used to connect the coplanar copper electrode pair 3 and the float glass 401.

[0070] The size of the float glass 401 is 70 mm in length, 50 mm in width, and 1.1 mm in thickness.

[0071] Meanwhile, the outer frame 1 comprises a bonding area 101 for bonding the coplanar copper electrode substrate 4 and a wire through hole 102 through which a wire is passed and connected to the coplanar copper electrode pair 3.

[0072] The present application preferably uses a float glass 401 as a substrate for etching the coplanar copper electrode pair 3. The copper etching process applied in the microfluidic field has the advantages of low cost, simple production, small environmental pollution, and lower short-circuit resistance compared with the traditional ITO glass etching process. The preparation method comprises the following steps:

[0073] Step one: 3 mL of UV glue 403 is added to the center of the float glass 401 and evenly spread. The UV glue 403 is a special UV glue 403 for bonding metal and glass;

[0074] Step two: the float glass 401 treated in step one is adsorbed on a spin coater, and is pre-rotated at a speed of 500 r / min for 15 s to make the UV glue 403 initially spin and evenly coated, and then is spin coated evenly on the spin coater at a speed of 1000 / min;

[0075] Step three: a copper foil with a length of 100 mm, a width of 100 mm, and a thickness of 20 μm is pasted on the float glass 401 on which the UV glue 403 is spin coated, and is pressed until there is no air bubble between the copper foil and the float glass 401 401;

[0076] Step four: an LED ultraviolet lamp is used to irradiate from the side of the float glass 401 which is not pasted with the copper foil. After exposure for 5 minutes until the UV glue 403 is cured, the LED ultraviolet lamp has a power of 20 watts and generates light with a wavelength of 365 nm;

[0077] Step five: the completely bonded copper foil is cut along the edge of the float glass 401, and the excess copper foil is removed;

[0078] Step six: clean the surface of the copper foil with anhydrous ethanol to remove oil stains on the surface of the copper foil, and blow the surface clean with pure nitrogen;

[0079] Step seven: mix the photosensitive blue oil and the non-white water diluent uniformly according to a volume ratio of 1:3 to obtain a photosensitive blue oil diluent;

[0080] Step eight: drop 2 mL of the photosensitive blue oil diluent on the copper foil and spread it evenly;

[0081] Step nine: adsorb the float glass 401 treated in step eight on the spin coater, pre-rotate at a speed of 500 r / min for 15 s to make the photosensitive blue oil spin uniformly, and then spin uniformly on the spin coater at a speed of 3000 / min;

[0082] Step ten: place the semi-finished product in an oven and dry at 45 degrees Celsius for 2 hours until the photosensitive blue oil diluent is completely dry;

[0083] Step eleven: design the copper electrode pattern needed and make a film mask;

[0084] Step twelve: attach the film mask to the surface of the dried photosensitive blue oil diluent and perform light shielding treatment, and expose it to light for 55 s on a URE-2000 / A type ultraviolet photoetching machine;

[0085] Step twelve: configure 202 g of a developing solution by mixing the photosensitive blue oil developer solid and distilled water according to a mass ratio of 1:100, immerse the exposed semi-finished product in the developing solution for 3 minutes, and use a clean brush to remove the unexposed photosensitive blue oil to expose part of the copper foil;

[0086] Step thirteen: rinse the surface of the semi-finished product with distilled water and dry the surface with nitrogen;

[0087] Step fourteen: configure 400 g of a copper etching solution by mixing the environmentally friendly copper etchant and distilled water according to a mass ratio of 1:3;

[0088] Step fifteen: heat the copper etching solution to 85 degrees Celsius on a hot plate, place the semi-finished product obtained in step thirteen in the copper etching solution and continuously stir to accelerate the etching of copper, maintain the temperature of the copper etching solution at 85 degrees Celsius throughout the process, and perform the process in a fume hood, and after 25 minutes of etching, take out the semi-finished product, rinse it with distilled water, and dry the surface with nitrogen;

[0089] Step sixteen: configure 105 g of a release solution by mixing the photosensitive blue oil release agent and distilled water according to a mass ratio of 1:20, and heat the release solution to 60 degrees Celsius on a hot plate;

[0090] Step seventeen: soak the semi-finished product of step fifteen in the demolding solution for 1 minute, brush off the exposed and cured photosensitive blue oil with a clean brush, then rinse with distilled water, and dry the surface with nitrogen;

[0091] Step eighteen: store the final coplanar copper electrode pair 3 product in a dry sealed place.

[0092] The rigid microfluidic chip 2 is preferably made of epoxy resin. Compared with the traditional PDMS chip, the elastic modulus thereof is about 1000MPa, and the characteristics of not easy to deform and strong sealing are conducive to the accuracy of the channel pressure detection.

[0093] The preparation method first adopts a soft lithography method to manufacture a silicon wafer convex mold, and then adopts a secondary reverse mold process to manufacture a rigid microfluidic chip 2 made of epoxy resin, and specifically includes the following steps:

[0094] Step one: drop 3mL of photoresist SU8-3035 on the surface of a 3-inch diameter silicon wafer and evenly spread it;

[0095] Step two: adsorb the silicon wafer on the spin coater, and pre-rotate at a speed of 500r / min for 15s to make the photoresist SU8-3035 preliminarily spin evenly, and then completely spin evenly on the spin coater at a speed of 3000 / min;

[0096] Step three: place the semi-finished product of step two on a heating table, heat at 95 degrees Celsius for 25 minutes until the photoresist SU8-3035 is completely cured, and obtain the first layer of photoresist;

[0097] Step four: drop 3mL of photoresist SU8-2075 on the surface of the cured photoresist SU8-3035 and evenly spread it;

[0098] Step five: adsorb the silicon wafer on the spin coater, and pre-rotate at a speed of 500r / min for 15s to make the photoresist SU8-2075 preliminarily spin evenly, and then completely spin evenly on the spin coater at a speed of 1000 / min;

[0099] Step six: place the semi-finished product of step five on a heating table, heat at 95 degrees Celsius for 90 minutes until the photoresist SU8-2075 is completely cured, and obtain the second layer of photoresist;

[0100] Step seven: drop 3mL of photoresist SU8-2075 on the surface of the cured photoresist SU8-2075 and evenly spread it;

[0101] Step eight: adsorb the silicon wafer on the spin coater, pre-rotate at 500 r / min for 15 s, so that the photoetching negative glue SU8-2075 is initially spin-coated uniformly, and then spin-coat uniformly on the uniform coating instrument at 1000 / min;

[0102] Step nine: place the semi-finished product of step eight on the heating table, heat at 95 degrees Celsius for 90 minutes, until the photoetching negative glue SU8-2075 is completely cured, and the third layer of photoetching glue is obtained;

[0103] Step ten: design the micro-channel structure pattern and make the film mask;

[0104] Step eleven: attach the film mask to the surface of the third layer of photoetching glue after curing, perform light shielding treatment, and expose on the URE-2000 / A type ultraviolet photoetching machine for 65 s;

[0105] Step twelve: place the exposed semi-finished product on the heating table, heat at 95 degrees Celsius for 2 hours, and perform post-baking treatment;

[0106] Step thirteen: after post-baking, take out the silicon wafer, and after the silicon wafer cools to room temperature, immerse it in the negative glue developing solution, and place it in the ultrasonic cleaning instrument together, ultrasonic cleaning for 5 minutes, until the unexposed photoetching glue is completely cleaned;

[0107] Step fourteen: clean the semi-finished product treated in step thirteen with anhydrous ethanol, and blow it clean with nitrogen;

[0108] Step fifteen: place the silicon wafer obtained by soft photoetching in a No. 1 culture dish, and configure 22 g of uniformly stirred PDMS premix according to the mass ratio of 10:1 between PDMS and curing agent, and pour the PDMS premix into the No. 1 culture dish;

[0109] Step sixteen: place the No. 1 culture dish in a vacuum tank, and vacuum for 30 minutes, until there are no bubbles in the premix;

[0110] Step seventeen: place the No. 1 culture dish in an oven, heat at 80 degrees Celsius for 2 hours, until the PDMS premix is completely cured;

[0111] Step eighteen: demold the cured PDMS, and cut it into a certain size with a knife;

[0112] Step nineteen: bond the PDMS and the float glass 401 after plasma treatment, with the side of the PDMS with channels facing up. After bonding, place the semi-finished product in a No. 2 culture dish;

[0113] Step twenty: configure 30 g of silicone premix according to the mass ratio of 1:1 between the semi-transparent silicone and the curing agent, and pour the configured silicone premix into the No. 2 culture dish in step nineteen;

[0114] Step twenty-one: Place the No. 2 culture dish in the vacuum tank, vacuum for 30 minutes, until the bubbles in the silica gel premix completely disappear;

[0115] Step twenty-two: Place the No. 2 culture dish in the oven, heat at 80 degrees Celsius for 1 hour, until the silica gel premix is completely solidified;

[0116] Step twenty-three: demold the solidified silica gel to obtain a silica gel mold, and cut it into a certain size with a knife;

[0117] Step twenty-four: prepare 25g of epoxy resin premix with a mass ratio of 3:1 between epoxy resin and curing agent, and pour the prepared epoxy resin premix into the silica gel mold obtained in step twenty-three;

[0118] Step twenty-five: Place the silica gel mold in the vacuum tank, vacuum for 30 minutes, until the bubbles in the epoxy resin premix completely disappear;

[0119] Step twenty-six: Place the silica gel mold in a cool and clean place and let it stand for 24 hours until the epoxy resin premix is completely solidified;

[0120] Step twenty-seven: demold the solidified epoxy resin from the silica gel mold to obtain the final rigid microfluidic chip 2 made of epoxy resin;

[0121] After the coplanar copper electrode pair 3 and the rigid microfluidic chip 2 are prepared, the two are pasted together using ultra-thin double-sided tape, and epoxy resin is poured again to seal, obtaining a T-shaped droplet generation chip based on a microchannel pressure sensor.

[0122] Step one: cut out the shape of the measurement blind end channel 202 of the rigid microfluidic chip 2 on the ultra-thin double-sided tape 402, that is, a rectangular window with a length of 20mm and a width of 1.5mm;

[0123] Step two: paste the cut ultra-thin double-sided tape 402 on the coplanar copper electrode pair 3, and the coplanar copper electrode pair 3 is exposed from the cut rectangular window without being covered;

[0124] Step three: paste the rigid microfluidic chip 2 on the semi-finished product obtained in step two, ensuring that the measurement blind end channel 202, the coplanar copper electrode pair 3, and the rectangular window cut in step two are centered and aligned;

[0125] Step four: use solder to solder 10cm copper wires to the outer pads of the first and second coplanar copper electrodes of the coplanar copper electrode pair 3, respectively;

[0126] Step four: 40g of epoxy resin premix solution was prepared by mixing epoxy resin and curing agent with a mass ratio of 3:1, and then the epoxy resin was poured on the semi-finished product obtained in step three;

[0127] Step five: the semi-finished product obtained in step four was placed in a vacuum tank, and vacuum was applied for 30 minutes until the bubbles in the epoxy resin premix solution completely disappeared;

[0128] Step six: the semi-finished product obtained in step five was placed in a cool and clean place, and was kept still for 24 hours until the epoxy resin premix solution completely cured.

[0129] Obviously, the above examples are only examples for the purpose of clarity, and are not intended to limit the embodiments. Based on the above description, other different forms of changes or variations can also be made by those of ordinary skill in the art. It is not necessary and impossible to enumerate all the embodiments. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A microchannel pressure sensor based on the resistance variation of coplanar copper electrodes, characterized in that, include: The outer frame (1) and the rigid microfluidic chip (2), the coplanar copper electrode pair (3), and the coplanar copper electrode substrate (4) are disposed inside the outer frame (1), the coplanar copper electrode pair (3) are disposed on the coplanar copper electrode substrate (4), and the rigid microfluidic chip (2) is disposed on the coplanar copper electrode substrate (4). The rigid microfluidic chip (2) includes an aqueous inlet (201), a measurement blind end channel (202), an oil inlet (203), a droplet outlet (204), a droplet outlet channel (205), an oil inlet channel (206), a T-junction (207), a test channel (208), and an aqueous inlet channel (209). The aqueous inlet (201) is located at one end of the aqueous inlet channel (209), and the oil inlet (203) is located at... One end of the oil phase inlet channel (206) and the droplet outlet (204) are located at one end of the droplet outlet channel (205). The water phase inlet channel (209), the measurement blind end channel (202), the oil phase inlet channel (206), and the droplet outlet channel (205) are spaced apart and are all connected to the channel to be measured (208). The intersection of the oil phase inlet channel (206) and the channel to be measured (208) is a T-shaped intersection (207). The measurement blind end channel (202) is a channel with only an inlet and no outlet. The measurement blind end channel (202) is aligned with the coplanar copper electrode. When the liquid flows through the measurement blind end channel (202), it will enter the measurement blind end channel (202) and squeeze the gas in the measurement blind end channel (202) until the gas pressure is equal to the liquid pressure. The movement of the liquid surface in the measurement blind end channel (202) will cause the resistance of the coplanar copper electrode pair (3) to change. The fluid pressure is calculated by measuring the resistance of the coplanar copper electrode pair (3).

2. A microchannel pressure sensor based on the resistance variation of coplanar copper electrodes according to claim 1, characterized in that, The aqueous phase inlet channel (209), the measurement blind end channel (202), the oil phase inlet channel (206), and the droplet outlet channel (205) are arranged in parallel.

3. A microchannel pressure sensor based on the resistance variation of coplanar copper electrodes according to claim 1, characterized in that, The aqueous phase inlet channel (209), the measurement blind end channel (202), the oil phase inlet channel (206), and the droplet outlet channel (205) are perpendicular to the channel to be measured (208).

4. A microchannel pressure sensor based on the resistance variation of coplanar copper electrodes according to any one of claims 1-3, characterized in that, The measurement blind end channel (202) is 20 mm long, 1.5 mm wide, and 500 μm high.

5. A microchannel pressure sensor based on the resistance variation of coplanar copper electrodes according to claim 4, characterized in that, The aqueous phase inlet (201) and droplet outlet (204) are circular openings with a diameter of 1.1 mm.

6. A microchannel pressure sensor based on the resistance variation of coplanar copper electrodes according to claim 5, characterized in that, The coplanar copper electrode pair (3) includes a first pad (302) and a second pad (303), a first measurement area (301) and a second measurement area (304), wherein the first pad (302) is connected to the first measurement area (301) and the second pad (303) is connected to the second measurement area (304).

7. A microchannel pressure sensor based on the resistance variation of coplanar copper electrodes according to claim 6, characterized in that, The width of the first measurement area (301) and the second measurement area (304) is 300 μm, and the distance between the first measurement area (301) and the second measurement area (304) is 300 μm.

8. A microchannel pressure sensor based on the resistance variation of coplanar copper electrodes according to claim 7, characterized in that, The first measurement area (301) and the second measurement area (304) are set parallel to and centered on the measurement blind end channel (202).

9. A microchannel pressure sensor based on the resistance variation of coplanar copper electrodes according to claim 1, characterized in that, The coplanar copper electrode substrate (4) includes float glass (401), ultra-thin double-sided tape (402), and UV adhesive (403). The float glass (401) is used to etch the substrate of the coplanar copper electrode pair (3). The ultra-thin double-sided tape (402) is used to connect the rigid microfluidic chip (2) and the coplanar copper electrode substrate (4). The UV adhesive (403) is used to connect the coplanar copper electrode pair (3) and the float glass (401).

10. A microchannel pressure sensor based on the resistance variation of coplanar copper electrodes according to claim 9, characterized in that, The outer frame (1) includes an adhesion area (101) and a wire through hole (102). The adhesion area (101) is used to bond the coplanar copper electrode substrate (4). The wire passes through the wire through hole (102) and is connected to the coplanar copper electrode pair (3).

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