Ciliary optical fluid sensor array and flow field testing method based on bionics

Abstract

The present invention discloses a bionics-based ciliary optical fluid sensor array and a flow field testing method. The ciliary optical fluid sensor array fabrication method includes steps S1-S7 of peeling off a PDMS pyramid array from a silicon template, adding a transparent mechanical force transmission layer to the upper surface of the PDMS pyramid, and fabricating cilia on the mechanical force transmission layer. The novel bionic ciliary optical fluid sensor array designed by the present invention realizes flow field testing by converting flow field information into optical information and combining it with artificial intelligence processing, eliminating the complex electrode wiring and signal processing circuit problems caused by the traditional bionic ciliary fluid sensor array converting flow field signals into electrical signals. The ciliary optical fluid sensor array is fabricated using conventional micro-nano processing techniques such as photolithography, wet etching, and PDMS microstructure fabrication. Based on this method, large-area sensor arrays can be designed and applied to typical flow field tests, turbulence tests, and prediction of critical conditions for boundary layer separation.

Description

Technical Field

[0001] The present invention relates to the field of MEMS fluid sensing technology, and in particular to a bionics-based ciliary optical fluid sensor array and a flow field testing method. Background Art

[0002] Fluid measurement technology is widely used in various fields of our lives, including military, civilian and biomedical fields. Fluid measurement mainly includes the measurement of typical flow fields, as well as the measurement of challenging technologies such as turbulence and critical conditions of boundary layer separation. Whether it is underwater unmanned vehicles, aerial drones, or many other application fields such as biomedicine, flow sensors are required to have high resolution, short response time, low cost and high durability. Traditional fluid sensing methods, such as hot wire anemometers (HWA), acoustic Doppler shift velocimeters and particle image velocimeters (PIV), cannot meet these requirements due to their large size, low sensitivity and complex setup. Thanks to the miniaturization, integration, low cost and mass production of MEMS technology, fluid measurement based on MEMS sensors has become an important means of fluid measurement technology, among which MEMS bionic ciliary fluid sensors are an important category of MEMS fluid sensors.

[0003] Humans and many other organisms, such as aquatic animals and amphibians, are equipped with highly sensitive ciliary fluid sensing systems to help them survive challenging environments. These sensing systems have been a key inspiration for the development of highly sensitive and high-performance artificial fluid sensors. Based on biomimetics and combined with MEMS technology, research institutions at home and abroad have designed MEMS ciliary fluid sensors based on various biomimetic and sensor principles. These include piezoresistive, piezoelectric, capacitive, and magnetic MEMS ciliary fluid sensors designed to mimic the lateral line system of fish, bats, crickets, seals, and the vestibular system of the human inner ear.

[0004] A single MEMS ciliary fluid sensor suffers from low resolution when capturing flow field information. In practical applications, arrays are often used to address the low resolution and incomplete flow field information captured by individual sensors. However, regardless of whether the sensor is piezoresistive, piezoelectric, or capacitive, specific electrodes must be designed for electrical interconnection. Affected by factors such as electrode line width, electrode spacing, and process conditions, the electrode arrangement will occupy a large portion of the device space. The complexity of array electrode wiring and the large amount of space occupied will severely limit the large-scale manufacturing of sensor arrays and reduce the resolution of the sensor array. Summary of the Invention

[0005] In order to overcome the deficiencies of the prior art, the present invention provides a bionics-based ciliary optical fluid sensor array and a flow field testing method.

[0006] To solve the above technical problems, the present invention provides the following technical solution: a biomimetic-based ciliary optical fluid sensor array, wherein the manufacturing method of the ciliary optical fluid sensor array comprises the following steps:

[0007] S1. First, a silicon nitride film b is deposited on the surface of single-crystal silicon by plasma-enhanced chemical vapor deposition (PECVD) as a mask layer for subsequent potassium hydroxide wet etching;

[0008] S2. Using conventional UV lithography, a photoresist (AR-P 5350) pattern is formed on the surface of the silicon nitride film obtained in S1.

[0009] S3, using the photoresist as a mask, using inductively coupled plasma etching technology (RIE etching) to etch the silicon nitride film exposed outside the photoresist in S2, so that the silicon nitride in the unmasked area is completely etched until the silicon layer is exposed;

[0010] S4, removing the residual photoresist after S3;

[0011] S5, using silicon nitride as a mask, utilizing the anisotropic characteristics of potassium hydroxide (KOH) wet etching to etch the silicon substrate exposed outside the silicon nitride mask layer after S4 is completed, to form a PDMS inverted pyramid array mold;

[0012] S6, mixing the base component of Dow Corning Sylgard 184 silicone rubber and two parts of the curing agent in a weight ratio of 10:1, vacuum evacuating, and pouring into the silicone template formed in S5;

[0013] S7. Peel off the PDMS pyramid array from the silicon template, add a transparent mechanical force transmission layer on the upper surface of the PDMS pyramid to better convert the displacement of the cilia into the deformation of the PDMS pyramid array, and make cilia on the mechanical force transmission layer.

[0014] The present invention also provides a flow field testing method for a bionics-based ciliary optical fluid sensor array to test the ciliary optical fluid sensor array as described above. The testing method adopts a testing system including a light source, a camera, a charge-coupled device (CCD) and a computer connected thereto, glass, and a bionic ciliary optical fluid sensor fixed on the glass surface. The method converts flow field information into optical information and combines it with artificial intelligence for processing, thereby eliminating complex electrodes and signal processing circuits.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] The present invention designs a flow field testing technology based on artificial intelligence and bionic ciliary optical fluid sensor arrays. This method converts flow field information into optical information and combines it with artificial intelligence processing methods to perform flow field testing and processing, completely eliminating the complex electrode wiring and signal processing circuit problems caused by the traditional bionic ciliary fluid sensor array converting flow field signals into electrical signals. The ciliary optical fluid sensor array of the present invention is manufactured using conventional micro-nano processing technologies such as photolithography, wet etching, and PDMS microstructure production. Based on this method, ultra-large area sensor array manufacturing and higher test resolution can be achieved, and it can be applied to typical flow field testing, turbulence testing, and prediction of critical conditions for boundary layer separation. At the same time, this technology shows excellent application prospects in the fields of drones, underwater unmanned submersibles, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the working principle of a single bionic ciliary optical fluid sensor of the present invention;

[0018] Figure 2 This is a schematic diagram of a method for manufacturing a biomimetic ciliary optical fluid sensor array according to the present invention;

[0019] Figure 3 (a) is a schematic diagram of light refraction when light is vertically incident on the upper half of the side wall of the PDMS pyramid according to the present invention;

[0020] Figure 3 (b) is a schematic diagram of light refraction when light is incident vertically onto the lower half of the side wall of the PDMS pyramid according to the present invention;

[0021] Among them: 1. Charge-coupled device (CCD); 2. Camera; 3. Bionic ciliary optical fluid sensor; 4. Cilia; 5. Mechanical force transmission layer; 6. PDMS inverted pyramid array; 7. Glass; 8. Light source; 9. Flow field; 10. Cilia swing; 11. Displacement caused by the mechanical force transmission layer; 12. Compressed pyramid array; 13. Single PDMS inverted pyramid; 14. Single compressed PDMS inverted pyramid; 15. Light spot array signal; 16. Strong optical signal; 17. Computer; 18. Single crystal silicon; 19. Silicon nitride; 20. Photoresist; 21. Light vertically incident on the upper half of the side wall of the PDMS pyramid microstructure; 22. Final output light; 23. Light partially reflected into the air gap between the PDMS pyramid microstructures; 24. Light vertically incident on the lower half of the side wall of the PDMS pyramid microstructure; 25. Light vertically incident on the unstructured area of ​​PDMS; 26. Light vertically incident on the tip of the PDMS pyramid microstructure. DETAILED DESCRIPTION

[0022] In order to make the technical means, creative features, purpose and efficacy of the present invention easy to understand, the present invention is further described below in conjunction with specific examples, but the following examples are only preferred embodiments of the present invention, not all. Based on the examples in the embodiments, other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention. The experimental methods in the following examples, unless otherwise specified, are conventional methods, and the materials, reagents, etc. used in the following examples, unless otherwise specified, can be obtained from commercial channels.

[0023] Example 1

[0024] Please refer to Figure 1 、 Figure 2 As shown, the present invention provides a bionics-based ciliary optical fluid sensor array, and the method for manufacturing the bionics ciliary optical fluid sensor array 3 includes the following steps:

[0025] S1. First, a silicon nitride film b is deposited on the surface of the single crystal silicon 18 by plasma enhanced chemical vapor deposition (PECVD) as a mask layer for subsequent potassium hydroxide wet etching;

[0026] S2. Using a conventional UV lithography method, a photoresist 20 (AR-P5350) pattern is formed on the surface of the silicon nitride film obtained in S1;

[0027] S3, using the photoresist 20 as a mask, using inductively coupled plasma etching technology (RIE etching) to etch the silicon nitride film exposed outside the photoresist 20 in S2, so that the silicon nitride 19 in the unmasked area is completely etched until the silicon layer is exposed;

[0028] S4, removing the remaining photoresist 20 after S3;

[0029] S5, using silicon nitride 19 as a mask, utilizing the anisotropic characteristics of potassium hydroxide (KOH) wet etching to etch the silicon substrate exposed outside the silicon nitride mask layer after S4 is completed, to form a PDMS inverted pyramid array 6 mold;

[0030] S6, mixing the base component of Dow Corning Sylgard 184 silicone rubber and two parts of the curing agent in a weight ratio of 10:1, vacuum evacuating, and pouring into the silicone template formed in S5;

[0031] S7, peeling off from the silicon template to form a PDMS pyramid array, adding a transparent mechanical force transmission layer 5 on the upper surface of the PDMS pyramid to better convert the displacement of the cilia 4 into the deformation of the PDMS pyramid array, and making cilia 4 on the mechanical force transmission layer 5;

[0032] In a specific embodiment of the present invention, a bionic ciliary optical fluid sensor 3 array is produced by the above S1-S7. When the bionic ciliary optical fluid sensor 3 is not placed in the flow field 9, the light signal emitted by the bottom light source 8 passes through the tip of the pyramid array and is captured and recorded by the camera 2 and CCD. The light signal presented at this time is a weak light spot array signal 15; when the bionic ciliary optical fluid sensor 3 is placed in the flow field 9, the fluid acts on the cilia 4, causing the cilia 4 to swing, the mechanical force transmission layer 5 to displace, and this displacement change is transferred to the bottom PDMS inverted pyramid array 6 structure, causing the PDMS inverted pyramid array 6 to deform and become a compressed pyramid array 12. The tip of the PDMS inverted pyramid is compressed and the area increases. At this time, the optical signal 16 through the pyramid tip is enhanced, and finally the change in this optical signal is stored in the computer 17 and analyzed in combination with artificial intelligence. The present invention converts the flow field 9 information into optical information and combines it with artificial intelligence processing methods to test and process the flow field 9, completely abandoning the complex electrode wiring and signal processing circuit problems caused by the traditional bionic ciliary 4 fluid sensor array converting the flow field 9 signal into an electrical signal.

[0033] Example 2

[0034] Please refer to Figure 1 As shown, the present invention provides a flow field testing method based on a bionic ciliary optical fluid sensor array, which tests the bionic ciliary optical fluid sensor 3 array as described above. The testing method adopts a testing system including a light source 8, a camera 2, a charge coupled device (CCD) and a computer 17 connected thereto, glass 7, and a bionic ciliary optical fluid sensor 3 fixed on the surface of the glass 7. The method converts flow field 9 information into optical information and combines it with artificial intelligence for processing, thereby eliminating complex electrodes and signal processing circuits.

[0035] In a specific embodiment of the present invention, the bionic ciliary optical fluid sensor 3 array of the present invention is manufactured using conventional micro-nano processing technologies such as photolithography, wet etching, and PDMS microstructure production. Based on this method, ultra-large area sensor array manufacturing and higher test resolution can be achieved, and can be applied to typical flow field 9 testing, turbulence testing, and prediction of critical conditions for boundary layer separation; at the same time, this technology shows excellent application prospects in the fields of drones, underwater unmanned submersibles, etc.

[0036] Working principle: First, a layer of silicon nitride film b is deposited on the surface of single crystal silicon 18 by plasma enhanced chemical vapor deposition (PECVD) as a mask layer for subsequent potassium hydroxide wet etching, and then a photoresist 20 (AR-P 5350) pattern is made on the surface of the obtained silicon nitride film using a traditional UV photolithography method. Then, the photoresist 20 is used as a mask and the silicon nitride film exposed outside the photoresist 20 is etched using inductively coupled plasma etching technology (RIE etching). The silicon nitride 19 in the unmasked area is completely etched until the silicon layer is exposed, and the residual photoresist 20 after S3 is removed. Using silicon nitride 19 as a mask, the silicon substrate exposed outside the silicon nitride mask layer is etched using the anisotropic characteristics of potassium hydroxide (KOH) wet etching to form a PDMS inverted pyramid array 6 mold, and then Dow Corning Sylgard The basic components of 184 silicone rubber and the two parts of the curing agent are mixed in a weight ratio of 10:1, vacuum-exhausted, and poured into the silicon template formed in the previous step. Finally, the PDMS pyramid array is peeled off from the silicon template to form a transparent mechanical force transmission layer 5. A transparent mechanical force transmission layer 5 is added to the upper surface of the PDMS pyramid to better convert the displacement of the cilia 4 into the deformation of the PDMS pyramid array, and cilia 4 are made on the mechanical force transmission layer 5. When the bionic cilia optical fluid sensor 3 is not placed in the flow field 9, the light signal emitted by the bottom light source 8 passes through the tip of the pyramid array and is captured by the camera 2 and CCD. Capture and record, the light signal presented at this time is a weak light spot array signal 15; when the bionic ciliary optical fluid sensor 3 is placed in the flow field 9, the fluid acts on the cilia 4, causing the cilia 4 to swing, the mechanical force transmission layer 5 to displace, and this displacement change is transferred to the bottom PDMS inverted pyramid array 6 structure, causing the PDMS inverted pyramid array 6 to deform and become a compressed pyramid array 12. The tip of the PDMS inverted pyramid is compressed and the area becomes larger. At this time, the optical signal 16 through the tip of the pyramid is enhanced, and finally the change of this optical signal is stored in the computer 17 and analyzed in combination with artificial intelligence.

[0037] Reference for the mechanism of light vertically incident on PDMS pyramid microstructures Figure 3 , when the light 21 is irradiated on the upper half of the side wall of the PDMS pyramid, as shown in Figure 3 (a) The incident angle of light at the PDMS / air interface is 54°, which is greater than the critical angle of total internal reflection of 47°, determined by the refractive indices of PDMS (n = 1.43) and air (n = 1.00). According to the law of refraction, the light undergoes total internal reflection at the PDMS / air interface and ultimately refracts out of the PDMS structure 23. However, during this process, some light 22 leaks into the air between the PDMS gaps and passes through the glass below. Because this leaked light encounters multiple interfaces during propagation, the final intensity of the light entering the glass is less than 10% of its initial intensity.

[0038] When the light 24 is irradiated on the lower half of the PDMS pyramid sidewall, Figure 3 (b) Light undergoes total internal reflection and enters the PDMS tip region 25. When light strikes the PDMS unstructured region 26 and the PDMS tip region 27 perpendicularly, it is reflected slightly but mostly passes through the underlying glass. Therefore, when light strikes the entire PDMS device perpendicularly, it can only pass through the PDMS microstructure tip region 25 and the PDMS unstructured region 26, but not through the sloping sidewalls of the PDMS microstructure.

[0039] While embodiments of the present invention have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents. The design and fabrication of microstructure templates include methods combining conventional photolithography with dry etching (reactive ion etching, inductively coupled plasma etching); combining conventional photolithography with wet etching (metal-assisted chemical etching, potassium hydroxide wet etching, etc.); and micron and nanoimprinting. Materials for the microstructure templates include semiconductor and dielectric materials such as silicon, silicon dioxide, and silicon nitride. Microstructure shapes include inverted pyramids, needles, and cylinders. Materials for the microstructures include a range of transparent, flexible polymer materials, such as PDMS. The size of a single microstructure ranges from 1 nm to 1 μm.

Claims

1. A biomimetic ciliary optical fluid sensor array, characterized by: The method for manufacturing a ciliary optical fluid sensor array comprises the following steps: S1. First, a silicon nitride film is deposited on the surface of the silicon wafer as a mask layer for subsequent potassium hydroxide wet etching; S2, patterning the device surface obtained in S1 with a photoresist (20) using a conventional photolithography method; S3, using the photoresist (20) as a mask, etching the silicon nitride film exposed outside the photoresist (20) in S2 using an inductively coupled plasma etching technique; S4, removing the remaining photoresist (20) after S3 is completed; S5, using silicon nitride (19) as a mask, utilizing the anisotropic characteristics of potassium hydroxide wet etching to etch the silicon substrate exposed outside the silicon nitride masking layer after S4 is completed, to form a silicon inverted pyramid array template; S6, mixing the base component of Dow Corning Sylgard 184 silicone rubber and two parts of the curing agent in a weight ratio of 10:1, vacuum evacuating, and pouring into the silicone template formed in S5; S7 is peeled off from the silicon template to form a PDMS pyramid array.

2. The bionics-based ciliary optical fluid sensor array according to claim 1, characterized in that: In S1, a silicon nitride film b is deposited on the surface of a single crystal silicon (18) by plasma enhanced chemical vapor deposition.

3. The bionics-based ciliary optical fluid sensor array according to claim 1, characterized in that: In S2, a photoresist (20) pattern is formed on the surface of the silicon nitride film using conventional ultraviolet lithography.

4. The bionics-based ciliary optical fluid sensor array according to claim 1, characterized in that: In S3 and S4, the photoresist (20) is used as a mask, and the silicon nitride (19) layer not covered by the photoresist (20) is etched by reactive ion etching, so that the silicon nitride (19) in the unmasked area is completely etched until the silicon layer is exposed, and the residual photoresist (20) is removed.

5. The bionics-based ciliary optical fluid sensor array according to claim 1, characterized in that: In S5, potassium hydroxide wet etching is performed using silicon nitride (19) as a mask to form a silicon inverted pyramid array mold.

6. The bionics-based ciliary optical fluid sensor array according to claim 1, characterized in that: In S7, for the PDMS pyramid array formed by peeling, a transparent mechanical force transmission layer (5) is added to the upper surface of the PDMS pyramid, so that the displacement of the cilia (4) can be better converted into the deformation of the PDMS pyramid array, and the cilia (4) are made on the mechanical force transmission layer (5).

7. A flow field testing method for a biomimetic ciliary optical fluid sensor array, characterized by: The ciliary optical fluid sensor array according to any one of claims 1 to 6 is tested, wherein the test system adopted by the test method includes a light source (8), a camera (2), a charge-coupled device (1) and a computer (17) connected thereto, glass (7), and a bionic ciliary optical fluid sensor (3) fixed on the surface of the glass (7), which converts flow field information into optical information and combines it with artificial intelligence for processing, thereby eliminating complex electrodes and signal processing circuits.

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