In-situ driven piezoelectric micro-fluidic device and preparation method thereof

Abstract

The invention discloses an in-situ driven piezoelectric micro-fluidic device and a preparation method thereof, and belongs to the technical field of driving and integrated preparation of micro-fluidic chips. The piezoelectric micro-fluidic device comprises a micro-channel, a micro-fluidic device substrate, a piezoelectric film and a metal interdigital electrode, a groove channel is formed in the surface of one side, facing the piezoelectric film, of the microfluidic device substrate; the micro-channel is a cavity defined by a piezoelectric film and the groove channel; and the metal interdigital electrode is arranged on the surface of one side, deviating from the micro-channel, of the piezoelectric film opposite to and over the micro-channel. According to the structural design of the in-situ driven piezoelectric micro-fluidic device, the micro-channel structure is arranged in the substrate, and the piezoelectric film and the metal interdigital electrode are prepared above the micro-channel structure of the substrate, so that the liquid is better controlled, the miniaturization and integration of the device are considered, and the performance requirement on a driving signal source is reduced.

Description

Technical Field

[0001] The present application relates to an in-situ driven piezoelectric microfluidic device and a preparation method thereof, belonging to the technical field of driving and integrated preparation of microfluidic chips. Background Art

[0002] Microfluidics is an emerging miniaturization technology that applies traditional fluid control technology to micron and nanometer-scale devices. Microfluidic chips, also known as chip labs, are the main platform for the implementation of microfluidics. At present, the main application form of microfluidic chips is to integrate or basically integrate the basic operating units such as sample preparation, reaction, separation, detection, cell culture, sorting, lysis, etc. involved in the fields of chemistry and biology into chips of a few square centimeters or even smaller, and controllable fluids run through the entire system through a microchannel network. Due to the advantages of low cost, good performance, low resource consumption and strong safety, microfluidic chips are widely used in daily life.

[0003] Most of the current microfluidic devices do not have their own power source and need to be driven by an external active system (pressure controller, syringe pump or peristaltic pump) or passive method (such as hydrostatic pressure), which cannot achieve flexible control of fluid samples and limits the further system integration of microfluidic devices. In recent years, people have found that in-situ, non-destructive and pollution-free manipulation of liquid samples can be achieved by integrating surface acoustic waves on microfluidic devices. The surface acoustic wave microfluidic chip mainly uses lithium niobate as the piezoelectric material, and metal interdigital electrodes are processed on its surface to generate surface acoustic waves, and the final surface acoustic wave microfluidic device is formed by bonding with the PDMS microchannel structure prepared by the reverse molding process. Although this type of device can effectively realize various microfluidic functions, such as particle separation, patterning, capture, focusing and other manipulations, its high operating frequency has a high demand for the excitation signal source. Increasing the size of the metal interdigital electrodes can effectively reduce the operating frequency of the surface acoustic wave microfluidic device, but it is not conducive to the miniaturization and integration of the microfluidic device. Therefore, realizing the integration and miniaturization of microfluidic devices is of great significance to the current field of piezoelectric acoustic wave microfluidic devices. Summary of the invention

[0004] In order to solve the problems existing in the prior art of microfluidic devices that require an external liquid injection system, which makes it difficult to flexibly control the fluid and causes the size of the microfluidic device to increase, and the problem that it is difficult to use lithium niobate piezoelectric surface acoustic wave microfluidic devices to simultaneously take into account low excitation signal frequency and narrow interdigital electrode distance, resulting in difficulty in miniaturization and integration of microfluidic chips, the present application proposes a technical solution for an in-situ driven piezoelectric microfluidic device, in which a microfluidic channel structure is placed in a substrate, and a piezoelectric film and metal interdigital electrodes are prepared above the substrate microfluidic structure, so as to better control the liquid while taking into account the miniaturization and integration of the device and reducing the performance requirements for the driving signal source.

[0005] This application adopts the following technical solutions:

[0006] According to a first aspect of the present application, there is provided an in-situ driven piezoelectric microfluidic device, comprising a microchannel, a microfluidic device substrate, a piezoelectric film, and metal interdigital electrodes;

[0007] A groove channel is arranged on the surface of the microfluidic device substrate facing the piezoelectric film;

[0008] The microchannel is a cavity surrounded by the piezoelectric film and the groove channel;

[0009] The metal interdigital electrodes are arranged on a surface of the piezoelectric film directly above the microchannel and facing away from the microchannel.

[0010] In one embodiment, an in-situ driven piezoelectric microfluidic device includes at least one pair of metal interdigitated electrodes;

[0011] The interdigitated fingers of each pair of metal interdigitated electrodes are arranged at intervals on the piezoelectric film along the length direction of the micro-fluidic channel.

[0012] In one embodiment, the thickness of the metal interdigitated electrode is 20 nm to 2 um.

[0013] Preferably, the material of the metal interdigital electrodes is selected from at least one of chromium, titanium, molybdenum, aluminum, gold and the like.

[0014] In one embodiment, the piezoelectric film has a thickness of 0.5 nm to 50 um.

[0015] In one embodiment, the material of the piezoelectric film is selected from at least one of aluminum nitride, lead zirconate titanate, lithium niobate, lithium tantalate, and the like.

[0016] In one embodiment, the piezoelectric film further includes at least two fluid inlet and outlet holes connected to the microchannel.

[0017] In one embodiment, the material of the microfluidic device substrate is an inorganic transparent material.

[0018] In one embodiment, the width of the microchannel is 20 um to 1000 um.

[0019] In one embodiment, the depth of the microchannel is 1 um to 300 um.

[0020] According to another aspect of the present application, a method for preparing an in-situ driven piezoelectric microfluidic device is provided, comprising the following steps:

[0021] A microfluidic device substrate having a groove channel on one side surface is obtained;

[0022] fabricating a piezoelectric film on a temporary substrate;

[0023] Bonding one side of the groove channel on the microfluidic device substrate to one side of the piezoelectric film on the temporary substrate, and then removing the temporary substrate to expose the piezoelectric film;

[0024] Patterned metal interdigital electrodes are prepared on the surface of the piezoelectric film on the side away from the microfluidic device substrate.

[0025] In one embodiment, a method for obtaining a microfluidic device substrate having a groove channel on one side surface includes:

[0026] A groove channel is formed by etching on the surface of one side of the microfluidic device substrate through at least one etching method selected from the group consisting of laser etching, wet etching and dry etching.

[0027] In one embodiment, a method for preparing a piezoelectric film on a temporary substrate includes:

[0028] Bonding a single crystal of a piezoelectric thin film material on a temporary substrate and then thinning it to obtain a piezoelectric thin film; or,

[0029] The piezoelectric film is obtained by depositing a piezoelectric film material on a temporary substrate.

[0030] In one embodiment, a method for preparing a patterned metal interdigitated electrode comprises:

[0031] An electrode pattern is formed on the piezoelectric film by a lift-off process, and then a material of the metal interdigital electrode is deposited to form a patterned metal interdigital electrode.

[0032] In one embodiment, the preparation method further comprises:

[0033] At least two fluid inlet and outlet holes connected with the micro-fluidic channel are etched on the piezoelectric film.

[0034] The beneficial effects of this application include:

[0035] (1) The microfluidic structure in the in-situ driven piezoelectric microfluidic device of the present application is placed in the substrate. Compared with other piezoelectric microfluidic channel structures, this method has a simple preparation process and does not require more space resources, which is conducive to the integration of microfluidic devices.

[0036] (2) The method of preparing a piezoelectric film on a substrate microfluidic structure in the present application can effectively avoid damage to the microfluidic structure during device preparation.

[0037] (3) The thickness of the piezoelectric film used in the present application is much smaller than the wavelength of the exciting sound wave. Compared with the traditional surface acoustic wave piezoelectric microfluidic device, the excitation frequency applied to excite the same wavelength can be reduced to several megahertz, reducing the requirements for the driving source (signal generator).

[0038] (4) The present application can generate plate waves on the piezoelectric film by applying an AC signal to the interdigitated electrodes, and can achieve in-situ driving of the fluid without the need for an external active system (such as a pump, etc.), thus having the function of flexibly driving the fluid.

[0039] (5) The in-situ driven piezoelectric microfluidic device prepared in this application can realize in-situ manipulation of fluids and is suitable for use in biomedical and drug testing fields such as drug synthesis and POCT. Compared with existing microfluidic drug generation, detection and diagnosis technologies, this technology can simplify the size of the equipment and can more conveniently achieve instant detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A schematic diagram of the three-dimensional structure of the piezoelectric microfluidic device of the present application;

[0041] Figure 2 A top view of the piezoelectric microfluidic device of the present application;

[0042] Figure 3 A cross-sectional view of the piezoelectric microfluidic device of the present application;

[0043] Figure 4 A top view of a microfluidic device with fluid inlet and outlet holes of the present application;

[0044] Figure 5 The vibration mode of the piezoelectric microfluidic device of the present application;

[0045] Figure 6 This is a flow chart of manufacturing a piezoelectric microfluidic device according to Example 1 of the present application;

[0046] Figure 7 This is the flowchart that needs to be replaced in Example 2 of the present application.

[0047] Figure ID

[0048] 1. Microfluidic device substrate; 2. Piezoelectric film layer; 3. Metal electrode layer; 4. Microchannel; 5. Fluid inlet and outlet holes. DETAILED DESCRIPTION

[0049] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0050] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0051] Unless otherwise specified, conventional methods were used for testing and instrument settings were those recommended by the manufacturer.

[0052] At present, many microfluidic devices require external active systems (syringe pumps, etc.) or passive methods (such as fluid hydrostatic pressure) to inject liquids, which not only makes it difficult to flexibly control fluids and samples, but also increases the size of the microfluidic equipment; although piezoelectric surface acoustic wave microfluidic devices based on lithium niobate have great advantages in driving and manipulating fluid samples, their excitation signals of tens or even hundreds of megahertz have great requirements on the driving source, and reducing the frequency of the excitation signal will increase the spacing between the interdigital electrodes, which is not conducive to the miniaturization and integration of microfluidic chips. Therefore, meeting the driving capability and integration requirements of microfluidic devices is a problem that needs to be solved urgently in this field. In order to solve the above problems, the present application provides an in-situ driven piezoelectric microfluidic device, such as Figures 1 to 3 As shown, it includes a microchannel 4, a microfluidic device substrate 1, a piezoelectric film 2, and a metal interdigital electrode 3;

[0053] A groove channel is arranged on the surface of the microfluidic device substrate 1 facing the piezoelectric film 2;

[0054] The microchannel 4 is a cavity surrounded by the piezoelectric film 2 and the groove channel;

[0055] The metal interdigital electrodes 3 are arranged on a surface of the piezoelectric film 2 opposite to the microchannel 4 and directly above the microchannel 4 .

[0056] In one embodiment, the in-situ driven piezoelectric microfluidic device comprises at least one pair of metal interdigital electrodes 3;

[0057] The interdigital fingers of each pair of metal interdigital electrodes 3 are arranged at intervals on the piezoelectric film 2 along the length direction of the microchannel 4. The arranged metal electrodes drive the piezoelectric film above the microchannel area to vibrate, generating bending plate waves driven in situ by the interdigital electrodes for the fluid, and the modal simulation is performed by finite element software, such as Figure 5 As shown in Figure 3, this mode demonstrates that the bending plate waves are excited by the interdigitated electrodes and propagate to both sides, thereby causing the movement of the fluid.

[0058] In one embodiment, the thickness of the metal interdigital electrode 3 is 20 nm to 2 um.

[0059] Preferably, the material of the metal interdigital electrodes 3 is selected from at least one of chromium, titanium, molybdenum, aluminum and gold.

[0060] In one embodiment, the thickness of the piezoelectric film 2 is 0.5 nm to 50 um.

[0061] The thickness of the piezoelectric film used in this application is much smaller than the wavelength of the exciting sound wave. Compared with the traditional surface acoustic wave piezoelectric microfluidic device, the excitation frequency applied to excite the same wavelength can be reduced to several megahertz, reducing the requirements for the driving source (signal generator).

[0062] In one embodiment, the material of the piezoelectric film 2 is selected from at least one piezoelectric material selected from aluminum nitride (AlN), lead zirconate titanate (PZT), lithium niobate (LN), and lithium tantalate (LT).

[0063] In one embodiment, the piezoelectric film 2 further includes at least two fluid inlet and outlet holes 5 connected to the microchannel 4, for example Figure 4 The structure shown.

[0064] In one embodiment, the microfluidic device substrate 1 is made of an inorganic transparent material.

[0065] In one embodiment, the substrate of the microfluidic device is a transparent material selected from glass or acrylic.

[0066] In one embodiment, the substrate of the microfluidic device is selected from a glass wafer, and its transparent property is conducive to the observation of the microfluidic experimental process.

[0067] In one of the embodiments, the present application can generate plate waves on the piezoelectric film by applying an AC signal to the interdigitated electrodes, and can achieve in-situ driving of the fluid without the need for an external active system (such as a pump, etc.), thereby having the function of flexibly driving the fluid.

[0068] In one embodiment, the width of the microchannel 4 is 20 um to 1000 um.

[0069] In one embodiment, the depth of the microchannel 4 is 1 um to 300 um.

[0070] The piezoelectric microfluidic device prepared in this application realizes in-situ manipulation of fluids and is suitable for use in biomedical and drug testing fields such as drug synthesis and POCT. Compared with existing microfluidic drug generation, detection and diagnosis technologies, this technology can simplify the size of the equipment and can more conveniently achieve instant testing.

[0071] In order to obtain the in-situ driven piezoelectric microfluidic device of the above structure, the present application discloses an in-situ driven piezoelectric microfluidic device and a preparation method thereof, wherein the microfluidic device has the ability to flexibly control the flow of fluid, and its structure includes a substrate with a microchannel, a piezoelectric film and a metal interdigital electrode, wherein the metal interdigital electrode is placed on the piezoelectric film directly above the microchannel and arranged along the length direction of the microchannel. The present application uses materials such as acrylic and glass as a microfluidic device substrate, forms a microchannel region on its surface by etching and the like, and sequentially bonds a piezoelectric film and a sputtered metal interdigital electrode on its surface to form a microfluidic device. In the present application, the wavelength of the sound wave determined by the size of the metal interdigital electrode is greater than the thickness of the piezoelectric film, so that a bending plate wave can be excited on the piezoelectric film, and the lower wave velocity of the bending plate wave can not only suppress the leakage of the sound wave energy in the liquid to better control the liquid, but also enable the microfluidic device to work in a low frequency band to reduce the performance requirements for the driving signal source. The microfluidic device has a simple process flow, and the area required for the device to generate driving sound waves is greatly reduced, which facilitates the formation of an integrated microfluidic chip.

[0072] In one embodiment, if Figure 6 and Figure 7 As shown, the present application provides a method for preparing an in-situ driven piezoelectric microfluidic device, comprising the following steps:

[0073] S1, obtaining a microfluidic device substrate 1 having a groove channel on one side surface;

[0074] S2, preparing a piezoelectric film 2 on a temporary substrate;

[0075] Bonding one side of the groove channel on the microfluidic device substrate 1 to one side of the piezoelectric film 2 on the temporary substrate, and then removing the temporary substrate to expose the piezoelectric film 2;

[0076] S3, preparing a patterned metal interdigital electrode 3 on the surface of the piezoelectric film 2 facing away from the microfluidic device substrate 1.

[0077] The specific method of obtaining a microfluidic device substrate 1 with a groove channel on one side surface is not strictly limited in this application. A microfluidic structure can be formed on the microfluidic device substrate 1, wherein the etching process as a preferred method includes but is not limited to laser, wet, dry and other etching processes. The microfluidic structure in the piezoelectric microfluidic device is located in the substrate. Compared with other piezoelectric microfluidic channel structures, this method has a simple preparation process, does not require more space resources, is conducive to the integration of microfluidic devices, and can effectively avoid damage to the microfluidic structure during the preparation of the device.

[0078] In one embodiment, in step S1, the method for obtaining a microfluidic device substrate 1 having a groove channel on one side surface includes:

[0079] A groove channel is formed by etching on one side surface of the microfluidic device substrate 1 by at least one etching method selected from the group consisting of laser etching, wet etching and dry etching.

[0080] In one embodiment, in step S2, the method for preparing the piezoelectric film 2 on the temporary substrate includes:

[0081] Bonding a single crystal of the piezoelectric film 2 material on a temporary substrate, and then thinning it to obtain the piezoelectric film 2; or,

[0082] The piezoelectric film 2 is obtained by depositing a piezoelectric film 2 material on a temporary substrate.

[0083] In one embodiment, the temporary substrate is selected from glass or silicon wafer.

[0084] In one embodiment, in step S2, the method of removing the temporary substrate is not strictly limited, and may be achieved by, for example, at least one of heat treatment, mechanical impact, spraying, ultrasonic vibration, and light irradiation.

[0085] In one embodiment, in step S3, the method for preparing the patterned metal interdigitated electrode 3 includes:

[0086] An electrode pattern is formed on the piezoelectric film 2 by a lift-off process, and then a material of the metal interdigital electrode 3 is deposited to form a patterned metal interdigital electrode 3 .

[0087] In one embodiment, the method for depositing the material of the metal interdigital electrodes 3 is not strictly limited, and may be, for example, magnetron sputtering or electron evaporation.

[0088] In one embodiment, the microchannel is directly prepared on the substrate of the microfluidic device, so that the microchannel structure is located inside the substrate of the microfluidic device. Compared with other piezoelectric microfluidic channel structures, this method has a simple preparation process and does not require more space resources, which is conducive to the integration of microfluidic devices.

[0089] In one embodiment, the preparation method further comprises:

[0090] At least two fluid inlet and outlet holes 5 communicating with the micro-channel 4 are etched on the piezoelectric film 2 .

[0091] Example 1 The first preparation process of the in-situ driven piezoelectric microfluidic device

[0092] Step 1: Prepare a glass wafer, a silicon wafer, and a LN piezoelectric single crystal, and ultrasonically clean them with acetone, alcohol, and deionized water for 10 to 20 minutes respectively, and blow dry them with high-purity nitrogen at 60 to 80°C to prevent moisture residue.

[0093] Step 2: Schematic diagram of etching to obtain microfluidic channels Figure 6 (a) to Figure 6 As shown in (b), prepare a first mask, select a dry etching process to etch a microchannel on a glass substrate, and the specific dry etching operation is as follows: load the glass substrate and the mask with a microchannel pattern placed above it into a dry etching device, establish a vacuum environment, introduce etching gas carbon tetrafluoride (CF4) into the reaction chamber, set the gas flow rate to 50sccm, and set the radio frequency (RF) power to 100w. The plasma generated by CF4 under the excitation of the RF power supply will react with the glass surface to achieve the effect of etching the glass, and the depth of the microchannel is controlled at 40um.

[0094] Step 3: Schematic diagram of obtaining piezoelectric film Figure 6 (a) To Figure 6 As shown in (c), the cleaned LN wafer is bonded to a temporary silicon substrate, wherein the bonding method is not particularly limited.

[0095] In one embodiment, the bonding method is selected from direct bonding or bonding through a bonding adhesive.

[0096] In one embodiment, the direct bonding is selected from room temperature bonding, diffusion bonding, plasma bonding or surface activated bonding methods.

[0097] Step 4: Figure 6 As shown in (d), the bonded LN wafer is thinned and polished using a wafer grinding, thinning and polishing machine. The specific thinning operation steps are: clean the workpiece surface, adsorb the silicon temporary substrate with LN on the suction cup in the thinning machine, and the LN wafer is located above the temporary substrate. First, the LN wafer is coarsely ground, the grinding wheel number of the thinning machine is set to 1000, the feed speed is 0.5~1um / s, and it is kept for 10min. Then, the LN wafer is finely ground, the grinding wheel number of the thinning machine is set to 3000, the feed speed is 0.1~0.2um / s, and the holding time is 15min. Finally, the thickness of LN is ground to 10um.

[0098] Step 5: Figure 6 As shown in (e), the glass substrate and the piezoelectric film are bonded, and the bonding method is the same as step 3, so that the microfluidic structure on the glass substrate is tightly combined with the LN piezoelectric film with the silicon temporary substrate.

[0099] Step 6: Figure 6 As shown in (f), the LN piezoelectric film and the silicon temporary bonding substrate are separated, and the temporary bonding substrate is removed to expose the LN piezoelectric film.

[0100] In one embodiment, the method of removing the temporary bonding substrate is selected from at least one of heat treatment, mechanical impact, spraying, ultrasonic vibration or light irradiation.

[0101] Step 7: Figure 6 (g) As shown, a second mask is provided to prepare the metal electrode on the surface of the piezoelectric film. The lift-off process is selected. The specific operation steps are: spin-coat a layer of positive photoresist on the upper surface of the LN piezoelectric film, place the second mask on the photoresist for photolithography, and the exposure time is 10s; remove the mask, put the photolithographic device into the developer to reveal the electrode pattern; then sputter the metal on the surface of the LN piezoelectric film by magnetron sputtering, and the vacuum degree is set to 10 -6 ~10 - 3 Torr, using argon (Ar) as the working gas; the gas flow rate is set to 10sccm, the temperature is set to within 200℃, the sputtering power is set to 50w, and the deposition rate is set to 1nm / s. The device first deposits a 20nm layer of metal chromium to protect the adhesion between the electrodes and improve corrosion resistance; then deposits an 80nm thick layer of metal gold as the main electrode to enhance the conductivity of the electrode. Finally, acetone is used to wash away the remaining photoresist.

[0102] In one embodiment, a small amount of nitrogen may also be added to the working gas to improve the properties of the membrane;

[0103] Step 8: Use a laser to etch the pre-marked LN piezoelectric film area, set the laser power to 5w, until the piezoelectric film is etched through, releasing the fluid inlet and outlet of the microfluidic structure, and obtaining a microfluidic device that can achieve in-situ driving and integration.

[0104] Example 2 Second preparation process of in-situ driven piezoelectric microfluidic device

[0105] Step 1: Prepare a glass wafer, a silicon wafer, and a LN piezoelectric single crystal, and ultrasonically clean them with acetone, alcohol, and deionized water for 10 to 20 minutes respectively, and blow dry them with high-purity nitrogen at 60 to 80°C to prevent moisture residue.

[0106] Step 2: Schematic diagram of etching to obtain microfluidic channels Figure 6 (a) to Figure 6As shown in (b), prepare a first mask, select a dry etching process to etch a microchannel on a glass substrate, and the specific dry etching operation is as follows: load the glass substrate and the mask with a microchannel pattern placed above it into a dry etching device, establish a vacuum environment, introduce etching gas carbon tetrafluoride (CF4) into the reaction chamber, set the gas flow rate to 50sccm, and set the radio frequency (RF) power to 100w. The plasma generated by CF4 under the excitation of the RF power supply will react with the glass surface to achieve the effect of etching the glass, and the depth of the microchannel is controlled at 40um.

[0107] Step 3: Schematic diagram of obtaining piezoelectric film Figure 7 (a) To Figure 7 As shown in (b), the cleaned silicon wafer is placed in the CVD reactor and heated to a set preheating temperature (usually 500°C to 600°C). Preheating helps to improve the crystal quality and uniformity of the film. The vacuum system is started and the reactor is evacuated to a certain vacuum degree (usually 10 -4 Up to 10 -2 Torr); introduce aluminum source gas (such as aluminum chloride AlCl3) and ammonia (NH3) at the same time, and control the ratio of AlCl3 to NH3 to be 1:3; set the deposition temperature of the reactor to 1000°C, the deposition rate to 0.2um / min, and the deposition time to 30min. After the deposition time is over, stop introducing aluminum source gas and ammonia, let the reactor cool naturally or gradually cool down the substrate temperature to room temperature through the cooling system, and finally obtain a 2um AlN piezoelectric film on the silicon temporary substrate.

[0108] In one implementation manner, in this embodiment, step 3 and step 4 in embodiment 1 are replaced by directly growing a piezoelectric thin film such as AlN or PZT on a temporary silicon substrate using a thin film deposition method.

[0109] Step 4: Figure 6 As shown in (e), the glass substrate and the piezoelectric film are bonded so that the microchannel structure on the glass substrate is tightly combined with the AlN piezoelectric film with the silicon temporary substrate. There is no particular limitation on the bonding method.

[0110] In one embodiment, the bonding method is selected from direct bonding or bonding through a bonding adhesive.

[0111] In one embodiment, the direct bonding is selected from room temperature bonding, diffusion bonding, plasma bonding or surface activated bonding methods.

[0112] Step 5: Figure 6 As shown in (f), the AlN piezoelectric film and the silicon temporary bonding substrate are separated, and the temporary bonding substrate is removed to expose the AlN piezoelectric film.

[0113] In one embodiment, the method of removing the temporary bonding substrate is selected from at least one of heat treatment, mechanical impact, spraying, ultrasonic vibration or light irradiation.

[0114] Step 6: Figure 6 (g) As shown, a second mask is provided to prepare the metal electrode on the surface of the piezoelectric film. The lift-off process is selected. The specific operation steps are: spin-coat a layer of positive photoresist on the upper surface of the AlN piezoelectric film, place the second mask on the photoresist for photolithography, and the exposure time is 10s; remove the mask, put the photolithographic device into the developer to reveal the electrode pattern; then sputter metal on the surface of the AlN piezoelectric film by magnetron sputtering, and the vacuum degree is set to 10 -6 ~10 -3 Torr, using argon (Ar) as the working gas; the gas flow rate is set to 10sccm, the temperature is set to within 200℃, the sputtering power is set to 50w, and the deposition rate is set to 1nm / s. The device first deposits a 20nm layer of metal chromium to protect the adhesion between the electrodes and improve corrosion resistance; then deposits an 80nm thick layer of metal gold as the main electrode to enhance the conductivity of the electrode. Finally, acetone is used to wash away the remaining photoresist.

[0115] In one embodiment, a small amount of nitrogen may also be added to the working gas to improve the properties of the membrane;

[0116] Step 7: Use a laser to etch the pre-marked AlN piezoelectric film area, set the laser power to 5W, until the piezoelectric film is etched through, releasing the fluid inlet and outlet of the microchannel structure, and obtaining a microfluidic device that can achieve in-situ driving and integration.

[0117] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. An in-situ driven piezoelectric microfluidic device, characterized in that: It includes microfluidic channel, microfluidic device substrate, piezoelectric film, and metal interdigital electrodes; A groove channel is arranged on the surface of the microfluidic device substrate facing the piezoelectric film; The microchannel is a cavity surrounded by the piezoelectric film and the groove channel; The metal interdigital electrodes are arranged on a surface of the piezoelectric film directly above the microchannel and facing away from the microchannel.

2. The in-situ driven piezoelectric microfluidic device according to claim 1, characterized in that: The in-situ driven piezoelectric microfluidic device includes at least one pair of metal interdigital electrodes; The interdigitated fingers of each pair of metal interdigitated electrodes are arranged at intervals on the piezoelectric film along the length direction of the micro-fluidic channel.

3. The in-situ driven piezoelectric microfluidic device according to claim 1, characterized in that: The thickness of the metal interdigitated electrode is 20nm to 2um; Preferably, the material of the metal interdigital electrodes is selected from at least one of chromium, titanium, molybdenum, aluminum and gold.

4. The in-situ driven piezoelectric microfluidic device according to claim 1, characterized in that: The thickness of the piezoelectric film is 0.5nm to 50um; Preferably, the material of the piezoelectric film is selected from at least one of aluminum nitride, lead zirconate titanate, lithium niobate, and lithium tantalate; Preferably, the piezoelectric film further includes at least two fluid inlet and outlet holes connected to the microchannel.

5. The in-situ driven piezoelectric microfluidic device according to claim 1, characterized in that: The material of the microfluidic device substrate is an inorganic transparent material; Preferably, the width of the microchannel is 20um to 1000um; Preferably, the depth of the microchannel is 1 um to 300 um.

6. The method for preparing the in-situ driven piezoelectric microfluidic device according to any one of claims 1 to 5, characterized in that: The steps include: A microfluidic device substrate having a groove channel on one side surface is obtained; fabricating a piezoelectric film on a temporary substrate; Bonding one side of the groove channel on the microfluidic device substrate to one side of the piezoelectric film on the temporary substrate, and then removing the temporary substrate to expose the piezoelectric film; Patterned metal interdigital electrodes are prepared on the surface of the piezoelectric film on the side away from the microfluidic device substrate.

7. The preparation method according to claim 6, characterized in that: The method for obtaining a microfluidic device substrate having a groove channel on one side surface comprises: A groove channel is formed by etching on the surface of one side of the microfluidic device substrate through at least one etching method selected from the group consisting of laser etching, wet etching and dry etching.

8. The preparation method according to claim 6, characterized in that: The method for preparing a piezoelectric film on a temporary substrate comprises: Bonding a single crystal of a piezoelectric thin film material on a temporary substrate and then thinning it to obtain a piezoelectric thin film; or, The piezoelectric film is obtained by depositing a piezoelectric film material on a temporary substrate.

9. The preparation method according to claim 6, characterized in that: The method for preparing the patterned metal interdigitated electrodes comprises: An electrode pattern is formed on the piezoelectric film by a lift-off process, and then a material of the metal interdigital electrode is deposited to form a patterned metal interdigital electrode.

10. The preparation method according to claim 6, characterized in that: The preparation method further comprises: At least two fluid inlet and outlet holes connected with the micro-fluidic channel are etched on the piezoelectric film.

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