A conductive film preparation device and method based on acoustic holographic microfluidics

Abstract

The present application belongs to the field of acoustofluidics and conductive composite materials, and in particular, relates to a conductive film preparation device and method based on acoustic holographic microfluidics, which utilizes acoustic holographic sound field modulation technology to pattern the conductive particles in a photosensitive solution; utilizes a curing lamp to cure the photosensitive solution to form a conductive film; and based on microfluidics technology, continuously introduces a photosensitive solution containing conductive particles, cures it, and pulls out a conductive film to achieve continuous preparation of the conductive film.

Description

Technical Field

[0001] The present application relates to the field of acoustic fluidics technology and conductive composite material technology, and in particular to a conductive film preparation device and method based on acoustic holographic microfluidics. Background Art

[0002] Strain sensors based on conductive films have great application potential in the fields of intelligent robots, human-machine interfaces, intelligent health monitoring, and personalized healthcare monitoring systems. Due to the limitations of metals and semiconductors in terms of sensitivity and elongation, people are exploring conductive composite materials as alternatives. Conductive composite materials have unique electrical, mechanical, and optical properties. They are usually composed of a polymer matrix and conductive particles dispersed in the matrix. The conductive particles are usually various forms of carbon, metal particles, etc. Conventional methods for preparing conductive films include spin coating, roll coating, and spray coating. In these methods, the conductive particles are randomly distributed in the polymer matrix. Only when the concentration of the conductive particles reaches the percolation threshold will a conductive path be formed in the polymer matrix. When the particle concentration is high, the fluidity of the composite solution is poor and the cured film has the disadvantages of uneven resistance distribution, poor flexibility, and easy damage. Studies have attempted to use external fields such as magnetic fields, electric fields, and acoustic fields to arrange the conductive particles in the solution before curing, so that the cured film has higher conductivity in a specific direction at a lower conductive particle concentration.

[0003] At present, there are many shortcomings in the methods of arranging conductive particles using external fields. For example, the use of magnetic fields to control conductive particles requires that the conductive particles have certain magnetic properties, which limits the types of conductive particles. When the conductive particles are controlled by electric fields, the dispersant on the surface of the particles changes the conductivity and dielectric constant of the polymer matrix solution, which has an adverse effect on the particle control. In comparison, the method of controlling conductive particles using acoustic fields mainly controls particles based on the acoustic radiation force generated by the radiation of sound waves into the liquid. It has the advantages of no labeling and little influence from external factors, and has greater development prospects. Studies have used bulk acoustic waves (BAW) or surface acoustic waves (SAW) to enrich and arrange conductive particles in microchambers to prepare conductive composite materials based on low filler concentrations. However, the current devices for arranging conductive particles based on acoustofluidics technology mostly rely on relatively arranged piezoelectric transducers to form a striped standing wave acoustic field, which has the disadvantages of complex structure and high manufacturing precision requirements. For example, the particle arrangement device based on SAW has problems such as high electrode manufacturing cost, high difficulty, and the chip is easily affected by temperature. Affected by the piezoelectric effect, the AC electric field generated by the vibration of the piezoelectric substrate in the control area will have an adverse effect on the arrangement of high aspect ratio conductive particles. BAW-based particle arrangement devices have the disadvantages of high requirements for matching the acoustic wavelength and chamber size, high difficulty in chip manufacturing, and difficulty in integration. In addition, the conductive films currently prepared by using acoustic fields to manipulate the arrangement of conductive particles are usually discontinuously formed and small in size, which is not conducive to their promotion and application in the field of flexible sensing.

[0004] Based on the above problems, it is necessary to design a device and method that is simple in device, stable in performance, easy to adjust, low in cost and can achieve continuous preparation of conductive films. Summary of the invention

[0005] The embodiments of the present application provide a device and method for preparing a conductive film based on acoustic holographic microfluidics, which fully considers the characteristics of conductive particles, utilizes the advantages of uniformity and stability of acoustic holographic sound field modulation, and the simplicity and detachability of the device, and combines it with microfluidics technology to achieve continuous, stable, efficient and low-cost preparation of conductive films.

[0006] To this end, according to one aspect of the present application, a conductive film preparation device based on acoustic holographic microfluidics is provided, comprising an acoustic holographic sound field modulation module, an ultrasonic dispersion injection module, a film pulling module, a connecting pipe and a curing lamp; the acoustic holographic sound field modulation module comprises an acoustic holographic chip and an acoustic wave excitation device arranged at the bottom of the acoustic holographic chip; the ultrasonic dispersion injection module comprises an injection pump and an ultrasonic dispersion syringe; the film pulling module comprises a winding roller and a pre-cured film having one end connected to the winding roller;

[0007] The acoustic holographic chip comprises an acoustic mask layer, a connecting layer and a microchannel layer arranged in sequence from bottom to top; the acoustic mask layer is provided with a groove microstructure with an isosceles trapezoidal cross section for modulating a striped standing wave acoustic field; the connecting layer is provided with a convex microstructure complementary to the groove microstructure for conducting acoustic waves and interlayer bonding; a photosensitive solution flow channel and a photosensitive solution chamber interconnected with each other are provided between the microchannel layer and the connecting layer, the horizontal position of the convex microstructure is located within the boundary of the photosensitive solution chamber, and a convex microstructure is provided on the microchannel layer away from the photosensitive solution flow channel. The photosensitive solution injection port is connected to one end of the photosensitive solution chamber, the ultrasonic dispersion syringe is connected to the photosensitive solution injection port through the connecting tube, the ultrasonic dispersion syringe is used to inject a photosensitive solution mixed with conductive particles into the photosensitive solution injection port, the microchannel layer is also provided with a notch connected to one end of the photosensitive solution chamber away from the photosensitive solution flow channel, the notch is used for inserting the end of the pre-cured film away from the winding roller into the photosensitive solution chamber, and the curing lamp is used to cure the photosensitive solution at the contact portion with the pre-cured film.

[0008] Optionally, a positioning groove connected to the notch and extending toward the protruding microstructure is provided on the lower surface of the microchannel layer, and a spacing is provided between the positioning groove and the protruding microstructure. The end of the pre-cured film away from the winding roller can be inserted into the positioning groove through the notch. The curing lamp is located above the acoustic holographic chip. The irradiation area of ​​the curing lamp is a strip, the long side of which is parallel to the width direction of the photosensitive solution chamber and is greater than the width of the photosensitive solution chamber, and the short side is greater than the spacing between the positioning groove and the protruding microstructure.

[0009] Optionally, the acoustic wave excitation device is a lead zirconate titanate piezoelectric transducer, and the lead zirconate titanate piezoelectric transducer is connected to the bottom of the acoustic mask layer at a position corresponding to the groove microstructure via a coupling liquid.

[0010] Optionally, in the groove microstructure, the upper base length of the isosceles trapezoid is 60 μm-100 μm, the lower base length is 500 μm, and the height is 170 μm-220 μm.

[0011] Optionally, the diameter of the photosensitive solution injection port is 2 mm, the width of the photosensitive solution flow channel is 1 mm, and the height is 200 μm; the width of the photosensitive solution chamber is 15 mm, and the height is 200 μm; the photosensitive solution flow channel and the photosensitive solution chamber are transitioned at an oblique angle, and the angle between the oblique angle and the channel is 30°-45°.

[0012] Optionally, the microchannel layer and the connecting layer are both made of polydimethylsiloxane, the microchannel layer is prepared by a soft lithography process, and the connecting layer is prepared by pouring polydimethylsiloxane on the acoustic mask layer through a mold; the contact surface between the microchannel layer and the connecting layer is bonded at room temperature by oxygen plasma treatment.

[0013] Optionally, the connection layer has a thickness of 30 μm-80 μm.

[0014] Optionally, the parameters of the groove microstructure are calculated by an iterative angular spectrum method; the calculation process includes the following steps: 1. drawing a binary amplitude diagram of the target stripe sound field; 2. calculating the angular spectrum of the target plane sound field; 3. back-propagating the angular spectrum to the surface of the sound mask, and calculating the complex sound pressure distribution; 4. retaining the phase of the sound field on the surface of the sound mask and resetting the amplitude; 5. calculating the angular spectrum of the sound mask surface after reset and forward transmitting it to the target plane; 6. calculating the sound field distribution of the target plane after transmission, comparing the error with the design value, and iteratively calculating.

[0015] According to another aspect of the present application, a method for preparing a conductive film based on acoustic holographic microfluidics is provided. Based on the conductive film preparation device as described above, the conductive film preparation method comprises the following steps:

[0016] Step 1: preparing a photosensitive solution containing conductive particles, and storing the photosensitive solution in the ultrasonic dispersion syringe;

[0017] Step 2: preparing a precured film, adhering one end of the prepared precured film to the winding roller, and inserting the other end into the photosensitive solution chamber through the notch;

[0018] Step 3: Turn on the built-in piezoelectric transducer in the ultrasonic dispersion syringe, use ultrasonic waves to disperse the conductive particles in the photosensitive solution in real time, and turn on the injection pump at the same time to inject the photosensitive solution stored in the ultrasonic dispersion syringe into the acoustic holographic chip until the photosensitive solution contacts the pre-cured film, turn on the curing lamp, cure the photosensitive solution by local illumination and connect it to the pre-cured film, and keep the curing lamp turned on afterwards;

[0019] Step 4: adjusting the injection rate of the injection pump and the rotation speed of the take-up roller to maintain a uniform injection speed of the photosensitive solution, and at the same time using the take-up roller to pull out the solidified conductive film. In this process, it is necessary to ensure that the injection rate of the photosensitive solution and the pull-out rate of the conductive film are balanced;

[0020] Step 5: Turn on the acoustic wave excitation device, observe the arrangement of the conductive particles through a stereo microscope, observe whether the pattern formed by the conductive particles is continuous, and at the same time fine-tune the injection rate of the injection pump and the rotation speed of the winding roller, change the injection rate of the photosensitive solution and the conductive film pulling-out rate until the pattern formed by the conductive particles is continuous, continue to inject the photosensitive solution and rotate the winding roller at a uniform speed, and continue to pull out the solidified conductive film to achieve continuous molding of the conductive film.

[0021] Optionally, in step 2, the precured film is made of the same base material as the conductive film, but does not contain conductive particles.

[0022] The conductive film preparation device and method based on acoustic holographic microfluidics provided in this application have at least the following beneficial effects:

[0023] 1. Taking into full consideration the influence of the electric field generated by the piezoelectric effect in the delay line region of traditional piezoelectric devices on the particle arrangement, the acoustic holography technology is used to arrange the conductive particles, which can more evenly and stably modulate the striped acoustic field in the micro-chamber and realize the arrangement of conductive particles with arbitrary aspect ratio;

[0024] 2. Combining microfluidics technology with holographic acoustic field modulation technology, continuously injecting photosensitive solution, arranging particles, solidifying and continuously pulling out the film, the continuous forming of the conductive film can be achieved, which can meet the requirements of different application scenarios for the size of flexible conductive films;

[0025] 3. The lead zirconate titanate piezoelectric transducer in the acoustic holographic sound field modulation module is reversibly connected to the acoustic holographic chip through a coupling liquid. The lead zirconate titanate piezoelectric transducer is reusable, the acoustic holographic chip is easy to replace, and different arrangements are easy to achieve. The acoustic holographic chip is formed by an injection molding process and has the advantages of high flexibility, replaceability, and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] in:

[0028] Figure 1 It is a schematic diagram of the overall structure of a conductive film preparation device based on acoustic holographic microfluidics shown in an embodiment of the present application;

[0029] Figure 2 It is a structural schematic diagram of an acoustic holographic sound field modulation module in an acoustic holographic microfluidics-based conductive film preparation device shown in an embodiment of the present application;

[0030] Figure 3 It is a schematic diagram of the microchannel layer structure of an acoustic holographic sound field modulation module in an acoustic holographic microfluidic-based conductive film preparation device according to an embodiment of the present application;

[0031] Figure 4 It is a schematic diagram of the connection layer structure of an acoustic holographic sound field modulation module in an acoustic holographic microfluidics-based conductive film preparation device shown in an embodiment of the present application;

[0032] Figure 5 It is a schematic diagram of the structure of an acoustic mask layer of an acoustic holographic sound field modulation module in an acoustic holographic microfluidic-based conductive film preparation device according to an embodiment of the present application;

[0033] Figure 6 It is a schematic cross-sectional view of an acoustic mask structure of a connecting layer and an acoustic mask layer in an acoustic holographic microfluidics-based conductive film preparation device according to an embodiment of the present application;

[0034] Figure 7 It is a structural schematic diagram of a film pulling module in a conductive film preparation device based on acoustic holographic microfluidics shown in an embodiment of the present application;

[0035] Figure 8 It is a schematic diagram of a conductive film prepared by a conductive film preparation device based on acoustic holographic microfluidics shown in an embodiment of the present application.

[0036] Description of main component symbols:

[0037] 1. Injection pump; 2. Ultrasonic dispersion syringe; 3. Connecting tube; 4. Microchannel layer; 5. Connecting layer; 6. Acoustic mask layer; 7. Coupling liquid; 8. Acoustic wave excitation device; 9. Curing lamp; 10. Pre-cured film; 11. Winding roller; 12. Photosensitive solution injection port; 13. Photosensitive solution flow channel; 14. Photosensitive solution chamber; 15. Notch; 16. Protruding microstructure; 17. Grooved microstructure; 18. Positioning groove; 19. Cured polymer matrix; 20. Linear array of conductive particles. DETAILED DESCRIPTION

[0038] In order to facilitate the understanding of the present application, the present application will be described more comprehensively with reference to the relevant drawings below. The preferred embodiments of the present application are provided in the drawings. However, the present application can be implemented in many other different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0039] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0040] It should be understood that the orientation or position relationship indicated by terms such as "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0042] According to one aspect of the present application, an embodiment of the present application provides a conductive film preparation device based on acoustic holographic microfluidics, such as Figure 1-Figure 7As shown, the conductive film preparation device includes an acoustic holographic sound field modulation module, an ultrasonic dispersion injection module, a film pulling out module, a connecting tube 3 and a curing lamp 9; the acoustic holographic sound field modulation module includes an acoustic holographic chip and an acoustic wave excitation device 8 arranged at the bottom of the acoustic holographic chip; the ultrasonic dispersion injection module includes an injection pump 1 and an ultrasonic dispersion syringe 2; the film pulling out module includes a winding roller 11 and a pre-cured film 10 connected to the winding roller 11 at one end. It should be noted here that the pre-cured film 10 is made of the same material as the base material of the conductive film to be prepared, but does not contain conductive particles. The acoustic holographic chip comprises an acoustic mask layer 6, a connecting layer 5 and a microchannel layer 4 which are arranged in sequence from bottom to top; the acoustic mask layer 6 is provided with a groove microstructure 17 which is an isosceles trapezoidal cross section and is used to modulate the striped standing wave acoustic field; the connecting layer 5 is provided with a convex microstructure 16 which is complementary to the groove microstructure 17 and is used for the conduction of acoustic waves and interlayer bonding; a photosensitive solution flow channel 13 and a photosensitive solution chamber 14 which are interconnected are provided between the microchannel layer 4 and the connecting layer 5, the convex microstructure 16 is horizontally located within the boundary of the photosensitive solution chamber 14, and a protruding microstructure 16 which is away from the light and is connected to the photosensitive solution flow channel 13 is provided on the microchannel layer 4. A photosensitive solution injection port 12 is connected to one end of the photosensitive solution chamber 14, and an ultrasonic dispersion syringe 2 is connected to the photosensitive solution injection port 12 through a connecting tube 3. The ultrasonic dispersion syringe 2 is used to inject a photosensitive solution mixed with conductive particles into the photosensitive solution injection port 12. The microchannel layer 4 is also provided with a notch 15 connected to one end of the photosensitive solution chamber 14 away from the photosensitive solution flow channel 13. The notch 15 is used for inserting one end of the pre-cured film 10 away from the winding roller 11 into the photosensitive solution chamber 14, and the curing lamp 9 is used to cure the photosensitive solution in contact with the pre-cured film 10.

[0043] The basic method of using the conductive film preparation device is as follows:

[0044] 1) Prepare a photosensitive solution containing uniformly dispersed conductive particles, and store the photosensitive solution in an ultrasonic dispersion syringe 2; 2) Prepare a precured film 10, insert one end of the prepared precured film 10 into the photosensitive solution chamber 14 through the gap 15 of the microchannel layer 4, and connect the other end to the winding roller 11; 3) Use the ultrasonic dispersion syringe 2 to disperse the conductive particles in the photosensitive solution in real time, inject the photosensitive solution into the acoustic holographic chip through the injection pump 1, and cure the photosensitive solution through local illumination of the curing lamp 9 and connect it to the precured film 10; 4) Turn on the acoustic wave excitation device 8 to arrange the conductive particles, continuously inject the photosensitive solution and rotate the winding roller 11 at a uniform speed, and continuously extract the cured conductive film to achieve continuous molding of the conductive film.

[0045] The present application fully considers the influence of the electric field generated by the piezoelectric effect in the delay line region of traditional piezoelectric devices on the arrangement of conductive particles, and adopts acoustic holography technology to arrange the conductive particles, which can more evenly and stably modulate the striped acoustic field in the microchamber and realize the arrangement of conductive particles with arbitrary aspect ratio.

[0046] The conductive particles in the photosensitive solution are patterned by using acoustic holographic field modulation technology; the photosensitive solution is cured by using a curing lamp 9 to form a conductive film; based on microfluidic technology, the photosensitive solution containing conductive particles is continuously introduced, cured, and the conductive film is pulled out to achieve continuous preparation of the conductive film.

[0047] It should be noted that the acoustic holographic sound field modulation technology uses an acoustic mask with a specific structure to control the plane longitudinal wave generated by the acoustic wave excitation device 8, forms sound pressure node lines with a specific spacing in the photosensitive solution, and uses the acoustic radiation force to enrich and arrange the conductive particles on the sound pressure node lines to form conductive straight lines, wavy lines and other complex continuous patterns. Among them, the conductive pattern corresponding to the acoustic mask structure in the embodiment of the present application is a linear array pattern.

[0048] In one embodiment, if Figure 1-Figure 3 As shown, the lower surface of the microchannel layer 4 is provided with a positioning groove 18 connected to the notch 15 and extending to the protruding microstructure 16, and a spacing is provided between the positioning groove 18 and the protruding microstructure 16. The end of the pre-cured film 10 away from the winding roller 11 can be inserted into the positioning groove 18 through the notch 15. The positioning groove 18 plays a role in positioning the insertion depth of the pre-cured film 10. The curing lamp 9 is located above the acoustic holographic chip. The irradiation area of ​​the curing lamp 9 is a strip, the long side of which is parallel to the width direction of the photosensitive solution chamber 14 and is greater than the width of the photosensitive solution chamber 14, and the short side is greater than the spacing between the positioning groove 18 and the protruding microstructure 16.

[0049] Specifically, the curing lamp 9 can locally cure the photosensitive solution at the contact point with the pre-cured film 10 through a slit of a specific size. The long side of the slit is parallel to the width direction of the photosensitive solution chamber 14 and is longer than the width of the photosensitive solution chamber 14. The short side width of the slit is about 200 μm.

[0050] In one embodiment, the acoustic wave excitation device 8 is a lead zirconate titanate (PZT) piezoelectric transducer, and the lead zirconate titanate piezoelectric transducer is connected to the bottom of the acoustic mask layer 6 at a position corresponding to the groove microstructure 17 through a coupling liquid 7. Preferably, the coupling liquid 7 is a water film with a thickness of 100 μm-300 μm.

[0051] According to the above arrangement, the lead zirconate titanate piezoelectric transducer is reversibly connected to the acoustic holographic chip through the water film, the lead zirconate titanate piezoelectric transducer is reusable, the acoustic holographic chip is convenient to replace, and different arrangement forms are easy to realize.

[0052] In a specific embodiment, Figure 2 and Figure 6As shown, in the groove microstructure 17, the length a of the upper base of the isosceles trapezoid is 60 μm-100 μm, the length of the lower base b is 500 μm, and the height h is 170 μm-220 μm.

[0053] The diameter of the photosensitive solution injection port 12 is 2 mm, the width of the photosensitive solution flow channel 13 is 1 mm, and the height is 200 μm; the width of the photosensitive solution chamber 14 is 15 mm, and the height is 200 μm; the photosensitive solution flow channel 13 and the photosensitive solution chamber 14 are transitioned through an oblique angle, and the angle between the oblique angle and the channel is 30°-45°.

[0054] In one embodiment, the microchannel layer 4 and the connecting layer 5 are both made of polydimethylsiloxane (PDMS for short), the microchannel layer 4 is prepared by soft photolithography, the connecting layer 5 is prepared by pouring polydimethylsiloxane on the acoustic mask layer 6 through a mold, and the thickness of the connecting layer 5 is 30μm-80μm; the contact surface of the microchannel layer 4 and the connecting layer 5 is bonded at room temperature by oxygen plasma treatment. In this way, the acoustic holographic chip is formed by injection molding, which has the advantages of high flexibility, replaceability and low cost.

[0055] It should be noted that the parameters of the groove microstructure 17 are calculated by the iterative angular spectrum method; the calculation process includes the following steps: 1. drawing a binary amplitude diagram of the target stripe sound field; 2. calculating the angular spectrum of the target plane sound field; 3. back-propagating the angular spectrum to the surface of the sound mask, and calculating the complex sound pressure distribution; 4. retaining the phase of the sound field on the surface of the sound mask and resetting the amplitude; 5. calculating the angular spectrum of the sound mask surface after reset and forward transmitting it to the target plane; 6. calculating the sound field distribution of the target plane after transmission, comparing the error with the design value, and iteratively calculating.

[0056] According to another aspect of the present application, an embodiment of the present application further provides a method for preparing a conductive film based on acoustic holographic microfluidics. Based on the conductive film preparation device in any of the above embodiments, the conductive film preparation method comprises the following steps:

[0057] Step 1: prepare a photosensitive solution containing conductive particles, and store the photosensitive solution in an ultrasonic dispersion syringe 2; specifically, mix the polymer matrix solution, photoinitiator, diluent and conductive particles in proportion, and then ultrasonically oscillate for 10 minutes to prepare a photosensitive solution, store the photosensitive solution in an ultrasonic dispersion syringe 2, and then use a connecting tube 3 to connect the outlet of the ultrasonic dispersion syringe 2 to the photosensitive solution injection port 12 of the acoustic holographic chip.

[0058] Step 2: Prepare a pre-cured film 10, adhere one end of the prepared pre-cured film 10 to the winding roller 11, and insert the other end into the photosensitive solution chamber 14 through the notch 15; specifically, use the same ratio of polymer matrix solution, photoinitiator and diluent as in step 1 to mix, and then ultrasonically vibrate for 10 minutes to prepare a pre-cured film 10 solution; stick two strip films with the same thickness as the conductive film to be prepared between two glass plates, and form a four-sided closed chamber with the two glass plates, and use a pipette to inject the pre-cured film 10 solution into it, and after curing with a curing lamp 9, cut it to a suitable size to ensure that it can be placed in the notch 15 on the acoustic holographic chip. Adhere one end of the pre-cured film 10 to the winding roller 11 with strong glue or strong tape, and insert the other end into the photosensitive solution chamber 14 through the notch 15 until it reaches the positioning groove 18.

[0059] Step 3: Turn on the built-in piezoelectric transducer in the ultrasonic dispersion syringe 2, use ultrasound to disperse the conductive particles in the photosensitive solution in real time, and at the same time turn on the injection pump 1 to inject the photosensitive solution stored in the ultrasonic dispersion syringe 2 into the acoustic holographic chip until the photosensitive solution contacts the pre-cured film 10, then turn on the curing lamp 9 to cure the photosensitive solution through local illumination and connect it to the pre-cured film 10, and the curing lamp 9 is kept on afterwards.

[0060] Step 4: Adjust the injection rate of the injection pump 1 and the rotation speed of the winding roller 11 to keep the photosensitive solution injected at a uniform speed, and at the same time pull out the cured conductive film with the winding roller 11. In this process, the injection rate of the photosensitive solution and the pulling rate of the conductive film must be balanced. Therefore, the conductive film polymer matrix should be selected from a material with a large elastic modulus and strong tensile strength after curing.

[0061] Step 5: Turn on the acoustic wave excitation device 8, observe the arrangement of the conductive particles through a stereo microscope, observe whether the pattern formed by the conductive particles is continuous, and at the same time fine-tune the injection rate of the injection pump 1 and the rotation speed of the winding roller 11, change the injection rate of the photosensitive solution and the conductive film pulling-out rate until the pattern formed by the conductive particles is continuous, continue to inject the photosensitive solution and rotate the winding roller 11 at a uniform speed, and continue to pull out the solidified conductive film to achieve continuous molding of the conductive film.

[0062] The conductive film preparation method utilizes acoustic holographic sound field modulation technology to pattern the conductive particles in the photosensitive solution; utilizes a curing lamp 9 to cure the photosensitive solution to form a conductive film; and based on microfluidic technology, continuously introduces the photosensitive solution containing the conductive particles, cures it, and pulls out the conductive film to achieve continuous preparation of the conductive film.

[0063] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0064] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A conductive film preparation device based on acoustic holographic microfluidics, characterized in that: It includes an acoustic holographic sound field modulation module, an ultrasonic dispersion injection module, a film pulling module, a connecting pipe and a curing lamp; the acoustic holographic sound field modulation module includes an acoustic holographic chip and a sound wave excitation device arranged at the bottom of the acoustic holographic chip; the ultrasonic dispersion injection module includes an injection pump and an ultrasonic dispersion syringe; the film pulling module includes a winding roller and a pre-cured film connected to the winding roller at one end; The acoustic holographic chip comprises an acoustic mask layer, a connection layer and a microchannel layer arranged in sequence from bottom to top; the acoustic mask layer is provided with a groove microstructure with an isosceles trapezoidal cross section for modulating a stripe-shaped standing wave acoustic field; the connection layer is provided with a convex microstructure complementary to the groove microstructure for conducting acoustic waves and interlayer bonding; A photosensitive solution flow channel and a photosensitive solution chamber that are interconnected are provided between the microchannel layer and the connecting layer. The horizontal position of the raised microstructure is located within the boundary of the photosensitive solution chamber. A photosensitive solution injection port that is connected to an end of the photosensitive solution flow channel away from the photosensitive solution chamber is provided on the microchannel layer. The ultrasonic dispersion syringe is connected to the photosensitive solution injection port through the connecting pipe. The ultrasonic dispersion syringe is used to inject a photosensitive solution mixed with conductive particles into the photosensitive solution injection port. A notch that is connected to an end of the photosensitive solution chamber away from the photosensitive solution flow channel is also provided on the microchannel layer. The notch is used for inserting an end of the precured film away from the winding roller into the photosensitive solution chamber. The curing lamp is used to cure the photosensitive solution at a portion in contact with the precured film.

2. The conductive film preparation device according to claim 1, characterized in that: The lower surface of the microchannel layer is provided with a positioning groove connected to the notch and extending to the protruding microstructure, and a spacing is provided between the positioning groove and the protruding microstructure. The end of the pre-cured film away from the winding roller can be inserted into the positioning groove through the notch. The curing lamp is located above the acoustic holographic chip. The irradiation area of ​​the curing lamp is a strip, the long side of which is parallel to the width direction of the photosensitive solution chamber and is larger than the width of the photosensitive solution chamber, and the short side is larger than the spacing between the positioning groove and the protruding microstructure.

3. The conductive film preparation device according to claim 1, characterized in that: The acoustic wave excitation device is a lead zirconate titanate piezoelectric transducer, and the lead zirconate titanate piezoelectric transducer is connected to the bottom of the acoustic mask layer at a position corresponding to the groove microstructure through a coupling liquid.

4. The conductive film preparation device according to claim 1, characterized in that: In the groove microstructure, the upper base length of the isosceles trapezoid is 60 μm-100 μm, the lower base length is 500 μm, and the height is 170 μm-220 μm.

5. The conductive film preparation device according to claim 1, characterized in that: The diameter of the photosensitive solution injection port is 2mm, the width of the photosensitive solution flow channel is 1mm, and the height is 200μm; the width of the photosensitive solution chamber is 15mm, and the height is 200μm; the photosensitive solution flow channel and the photosensitive solution chamber are transitioned through an oblique angle, and the angle between the oblique angle and the channel is 30°-45°.

6. The conductive film preparation device according to claim 1, characterized in that: The microchannel layer and the connecting layer are both made of polydimethylsiloxane. The microchannel layer is prepared by soft lithography, and the connecting layer is prepared by pouring polydimethylsiloxane on the acoustic mask layer through a mold; the contact surface between the microchannel layer and the connecting layer is bonded at room temperature by oxygen plasma treatment.

7. The conductive film preparation device according to claim 6, characterized in that: The thickness of the connecting layer is 30 μm-80 μm.

8. The conductive film preparation device according to claim 1, characterized in that: The parameters of the groove microstructure are calculated by an iterative angular spectrum method; the calculation process includes the following steps:

1. drawing a binary amplitude diagram of the target stripe sound field; 2. calculating the angular spectrum of the target plane sound field; 3. back-propagating the angular spectrum to the surface of the sound mask and calculating the complex sound pressure distribution; 4. retaining the phase of the sound field on the surface of the sound mask and resetting the amplitude; 5. calculating the angular spectrum of the sound mask surface after reset and forward transmitting it to the target plane; 6. calculating the sound field distribution of the target plane after transmission, comparing the error with the design value, and iteratively calculating.

9. A method for preparing a conductive film based on acoustic holographic microfluidics, based on the conductive film preparation device according to any one of claims 1 to 8, characterized in that: The conductive film preparation method comprises the following steps: Step 1: preparing a photosensitive solution containing conductive particles, and storing the photosensitive solution in the ultrasonic dispersion syringe; Step 2: preparing a precured film, adhering one end of the prepared precured film to the winding roller, and inserting the other end into the photosensitive solution chamber through the notch; Step 3: Turn on the built-in piezoelectric transducer in the ultrasonic dispersion syringe, use ultrasonic waves to disperse the conductive particles in the photosensitive solution in real time, and turn on the injection pump at the same time to inject the photosensitive solution stored in the ultrasonic dispersion syringe into the acoustic holographic chip until the photosensitive solution contacts the pre-cured film, turn on the curing lamp, cure the photosensitive solution by local illumination and connect it to the pre-cured film, and keep the curing lamp turned on afterwards; Step 4: adjusting the injection rate of the injection pump and the rotation speed of the take-up roller to maintain a uniform injection speed of the photosensitive solution, and at the same time using the take-up roller to pull out the solidified conductive film. In this process, it is necessary to ensure that the injection rate of the photosensitive solution and the pull-out rate of the conductive film are balanced; Step 5: Turn on the acoustic wave excitation device, observe the arrangement of the conductive particles through a stereo microscope, observe whether the pattern formed by the conductive particles is continuous, and at the same time fine-tune the injection rate of the injection pump and the rotation speed of the winding roller, change the injection rate of the photosensitive solution and the conductive film pulling-out rate until the pattern formed by the conductive particles is continuous, continue to inject the photosensitive solution and rotate the winding roller at a uniform speed, and continue to pull out the solidified conductive film to achieve continuous molding of the conductive film.

10. The method for preparing a conductive film according to claim 9, characterized in that: In step 2, the pre-cured film is made of the same base material as the conductive film, but does not contain conductive particles.

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