High-frequency dynamic response flexible membrane array sensor based on alveolar biomimetic structure and preparation method thereof

Abstract

The application relates to a preparation method of a high-frequency dynamic response flexible thin film array sensor based on alveolar biomimetic structure, and belongs to the technical field of pressure sensors. First, a flexible polymer thin film is spin-coated on a glass sheet and solidified, a metal thin film is deposited on the surface of the flexible polymer thin film, a photoresist is spin-coated on the surface of the metal thin film, and the photoresist and the metal thin film are patterned; second, photoresist type polyimide is spin-coated on the surface of the patterned metal thin film, and the photoresist type polyimide is patterned to expose only the interdigital unit area and the pad area; third, a pressure sensitive layer microstructure prepared from a nano-composite material is integrally bonded with the interdigital area of the encapsulated photoresist type polyimide sheet; and finally, high-temperature-resistant silicone rubber is spin-coated on the surface of the pressure sensitive layer to obtain a flexible piezoresistive sensor. The application has high-frequency response characteristics and high sensitivity, can be seamlessly attached to the inner wall of a complex curvature casing, can realize in-situ high-fidelity capture of the space-time distribution of wind pressure in a high-temperature and limited space environment, and provides a data cornerstone for intelligent perception and active flow control of a turbine engine.

Description

Technical Field

[0001] This invention belongs to the field of sensor technology and relates to a high-frequency dynamic response flexible thin-film array sensor based on alveolar biomimetic structure and its fabrication method. Background Technology

[0002] One of the core challenges to the performance and safety of turbofan engines lies in the real-time and accurate monitoring of the extremely complex flow fields inside the compressor and turbine casing. The casing walls are subjected to drastically changing aerodynamic pressures, and their dynamic characteristics (such as pressure pulsation amplitude, frequency, and spatial distribution) are directly related to engine surge, rotating stall boundary prediction, aerodynamic efficiency assessment, and structural fatigue life analysis. According to the Association for Aero Engines International (AAEII), most non-containment failures originate from structural resonance induced by aerodynamic instability. Therefore, obtaining high spatiotemporal resolution pressure distribution maps of the casing walls has become the cornerstone of modern high-performance aero-engine design, health management, and active control strategy optimization. Technological breakthroughs in this area have irreplaceable value in improving thrust-to-weight ratio, fuel economy, and flight safety redundancy.

[0003] Traditional wind pressure sensing technologies face multiple physical and engineering bottlenecks in applications within the harsh internal environment of aircraft casings. While current piezoelectric sensors offer fast response times, they struggle to maintain stable output under high temperatures and strong vibrations, and cannot be directly fitted onto complex curved surfaces. Rigid sensor arrays based on MEMS technology are limited by packaging size and wiring complexity; embedding them requires cutting and drilling into thin-walled casings, severely weakening structural strength and introducing additional aerodynamic disturbances and potential leakage points. Existing flexible piezoresistive sensors, while possessing the advantage of conformal surface design, generally suffer from inherent problems such as a sharp drop in sensitivity, significant hysteresis, insufficient dynamic response bandwidth, and poor long-term stability under high-temperature, high-pressure, and pulsating coupling conditions, making it difficult to meet the stringent signal-to-noise ratio and reliability requirements of aerospace-grade monitoring.

[0004] Emerging biomimetic design concepts offer a promising technological path to resolving the aforementioned contradictions. In nature, ingenious structures such as the gradient layered structure of armadillo scales and the curved micro-dome arrays of insect compound eyes demonstrate an extraordinary ability to achieve efficient gradient transmission of mechanical signals, optimized distribution of local stress, and high-density integration within limited space. Inspired by this, researchers have begun exploring the design of gradient-based, microstructured flexible sensing units. For example, biomimetic micro-dome structures with hardness gradients have been shown to significantly improve the pressure response linearity and sensitivity threshold of flexible piezoresistive materials. However, key bottlenecks remain for existing biomimetic flexible sensors, such as insufficient resolution in ultra-high dynamic pressure ranges (e.g., instantaneous pulsations within a casing) and the susceptibility to creep in high-temperature polymer substrates. More innovative structure-material co-design is urgently needed. Summary of the Invention

[0005] To address existing problems, this invention provides a high-frequency dynamic response flexible thin-film array sensor based on an alveolar biomimetic structure and its fabrication method. Combining a high-temperature resistant polyimide flexible substrate with micro / nano-scale precision manufacturing processes, a biomimetic multilayer hemispherical microstructure sensing unit with a controllable stiffness gradient is designed. This sensor exhibits high-frequency dynamic response characteristics (better than 20kHz), seamlessly attaches to the inner wall of a complex curvature casing, and achieves in-situ high-fidelity capture of the spatiotemporal distribution of wind pressure in high-temperature, confined-space environments, providing a data foundation for intelligent engine sensing and active flow control.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for fabricating a high-frequency dynamic response flexible thin-film array sensor based on alveolar biomimetic structures, the method specifically including the following steps: Step 1: Spin-coat a flexible polymer substrate onto a glass slide and cure it. Then, deposit a metal film on the surface of the flexible polymer using a thin film deposition method.

[0007] Furthermore, the flexible polymer substrate is polyimide, and the metal film is gold. The film deposition method is magnetron sputtering.

[0008] Step 2: Spin-coat a layer of photoresist film onto the surface of the metal film. Ultraviolet light is irradiated onto the substrate surface with the photoresist film through a mask. After development, the metal film is patterned. Then, the photoresist on the surface is removed with acetone. In other words, the photoresist and metal film are patterned.

[0009] Furthermore, the metal thin film patterning method in step 2 is a standard photolithography process and wet etching. Specifically, an ultraviolet lithography machine is used to irradiate the substrate surface with the photoresist film through a mask, patterning the photoresist on the flexible polymer surface. A 25% AZ400K solution (a mixture of deionized water and AZ400K solution at a volume ratio of 3:1) is used as the developing solution to remove the exposed photoresist. The unexposed photoresist then serves as a protective layer in the subsequent etching process. A gold etching solution is used to remove the metal thin film without photoresist protection. Finally, an appropriate amount of acetone is used to remove the surface photoresist, resulting in a patterned electrode pattern on a polyimide substrate. The photoresist is AZ703 positive photoresist. The gold etching solution is prepared from water, I2, and KI, with 1g of I2 and 1g of KI added to every 50mL of H2O.

[0010] Step 3: Spin-coat a photolithographic polyimide film onto the substrate surface patterned in Step 2. Use ultraviolet light to irradiate the substrate surface with the photolithographic polyimide film through a chromium plate to perform photolithography. After development and shaping, only the interdigitated electrode area and electrode pad area are exposed. Finally, the polyimide is cured.

[0011] Furthermore, the photolithographic polyimide patterning method in step 3 is a standard photolithography process and wet etching. Specifically, an ultraviolet lithography machine is used to irradiate the substrate surface with the photolithographic thin film through a chromium plate, patterning the photoresist on the flexible polymer surface. RS120 solution is used as the developing solution to remove the unexposed photolithographic polyimide, and PEGMA solution is used for shaping. Finally, the patterned polyimide is placed in an oven for curing. The photolithographic polyimide is BL301 negative photolithographic polyimide.

[0012] Step 4: Prepare a conductive nanocomposite solution using a one-pot method. Spin-coat the conductive nanocomposite solution onto a 3D-printed biomimetic patterned resin mold. After the conductive nanocomposite solution cures and is demolded, a flexible pressure-sensitive layer containing microstructures is formed.

[0013] Furthermore, the biomimetic patterned resin mold is provided with multiple grooves, which are composed of alternating arrays of deep and shallow grooves to form a microstructure for the flexible pressure-sensitive layer. The flexible pressure-sensitive layer containing the microstructure in step 4 is inspired by the multi-level fractal structure of alveoli (primary vesicle - secondary microvesicles). The microstructure is designed as a semi-ellipsoidal structure with two gradients. The first gradient semi-ellipsoidal structure is formed corresponding to the deep groove at the bottom of the mold, and the second gradient semi-ellipsoidal structure is formed corresponding to the shallow groove at the bottom of the mold. The ratio of the major axis of the first gradient semi-ellipsoidal structure to the second gradient semi-ellipsoidal structure is 1:(1.5~2.5), the ratio of the middle axis is 1:(1.5~2.5), and the ratio of the minor axis is 1:(1.5~2.5). The ratio of the major axis, the ratio of the middle axis, and the ratio of the minor axis are all preferably 1:2.

[0014] Furthermore, in step 4, the one-pot method involves adding conductive nanomaterials and high-temperature resistant silicone rubber to a volatile solvent, heating and magnetically stirring to fully disperse the conductive nanomaterials in the mixture solution, forming a nanocomposite solution, and then performing post-treatment to obtain a conductive nanocomposite solution.

[0015] Furthermore, the conductive nanomaterial is a carbon nanotube with a diameter of 5-15 nm and a length of 10-30 μm; the high-temperature resistant silicone rubber is silicone rubber GD401; and the volatile solvent is naphtha. Based on 20 ml of the volatile solvent, the amount of conductive nanomaterial added is 0.15-0.25 g, preferably 0.2 g; and the amount of high-temperature resistant silicone rubber added is 4-6 g, preferably 5 g.

[0016] Furthermore, before spin-coating the conductive nanocomposite solution onto the surface of the biomimetic patterned resin mold, a layer of release agent is sprayed onto the surface of the mold. (Per 1cm) 2 1 mL of conductive nanocomposite solution was spin-coated onto the surface of the biomimetic patterned resin mold.

[0017] Step 5: Integrate and bond the flexible pressure-sensitive layer obtained in Step 4 and the metal-film-patterned flexible polymer substrate obtained in Step 3. Furthermore, in step 5, the prepared conductive nanocomposite solution is rotated at high speed on a glass slide, and the tip of the flexible pressure-sensitive layer containing microstructures after demolding in step 4 is attached to the surface of the glass slide containing a thin layer of conductive nanocomposite material, so that a layer of conductive nanocomposite solution is adhered to the tip of the microstructure, and the surface of the interdigitated electrode area of ​​the flexible pressure-sensitive layer and the patterned flexible polymer substrate containing a metal thin film is integrally bonded.

[0018] Step 6: Spin-coat high-temperature resistant silicone rubber onto the entire surface of the flexible piezoresistive layer to complete the encapsulation of the flexible piezoresistive sensor and obtain a flexible thin-film array sensor.

[0019] Further, in step 6, the high-temperature resistant silicone rubber (JB 505) is prepared in a certain proportion (by mass ratio, matrix:curing agent = 10:1), and after thorough mixing and cross-linking, it is placed in a vacuum oven and vacuumed for 10 minutes. Then, the area except for the pressure-sensitive layer is protected with blue film tape, and the high-temperature resistant silicone rubber is spin-coated onto the entire surface of the flexible pressure-sensitive layer. After removing the blue film, the encapsulation of the flexible piezoresistive sensor is completed. Finally, the flexible piezoresistive sensor is cut to the size that meets the application requirements.

[0020] Step 7: Use anisotropic conductive adhesive to hot-press and align the externally processed flexible printed circuit board and the electrode pad area of ​​the flexible thin film array sensor. The area of ​​the anisotropic conductive adhesive is cut to be the same as the pad area of ​​the flexible thin film array sensor.

[0021] A high-frequency dynamic response flexible thin-film array sensor based on alveolar biomimetic structure is fabricated using the above-described method. The flexible piezoresistive sensor prepared by this invention can achieve high integration of sensing units, seamlessly attach to the inner wall of a complex curvature casing, and realize in-situ high-fidelity capture of the spatiotemporal distribution of wind pressure in high-temperature, high-vibration, and confined space environments.

[0022] An application of a high-frequency dynamic response flexible thin-film array sensor based on alveolar biomimetic structure is described, which is seamlessly attached to the inner wall of a complex curvature casing to achieve monitoring of the internal pressure of a turbofan engine compressor and detection of the periodic frequency response of the fan blades each time they pass the sensor.

[0023] Compared with existing flexible sensor fabrication methods, the present invention has the following advantages: (1) This invention can break through the bottleneck of high frequency dynamic response. The dynamic response frequency of the sensor is better than (20kHz). The alveolar multi-level fractal structure (main cavity-secondary microbubble) forms a hierarchical resonance system, which decomposes the high frequency pressure wave into microstructure responses of different scales, significantly broadening the effective bandwidth.

[0024] (2) The present invention can solve the bottleneck of conformal integration of complex curved surfaces and micro-manufacturing process. Existing rigid MEMS sensors are difficult to achieve conformal integration with curved surfaces when monitoring pressure, and the inherent structure of the sensor will destroy the flow field inside the compressor.

[0025] (3) The sensor of the present invention has a short installation time and a simple manufacturing process. When in use, only a slit (<1mm) needs to be opened on the surface of the casing. In contrast, drilling multiple rows of holes when installing a rigid MEMS sensor array will cause significant damage to the casing itself. The high sensitivity and high frequency response of this sensor can effectively promote the improvement of my country's modern high-performance aero-engine design, health management and active control strategy optimization capabilities. Attached Figure Description

[0026] Figure 1 It is polyimide spin-coated onto the surface of a glass slide; Figure 2 It is a metal thin film deposited on the surface of polyimide; Figure 3 It involves spin-coating photoresist onto a metal thin film surface and patterning the photoresist and the metal thin film. Figure 3 (a) in the figure is a side view of a patterned metal thin film; Figure 3 (b) is a top view of a patterned metal thin film; Figure 4 The design was inspired by a biomimetic pressure-sensitive layer and a patterned metal thin film. The surface of the film was then spin-coated with photolithographic polyimide and patterned. Figure 5 This involves the preparation of a conductive nanocomposite pressure-sensitive layer.

[0027] Figure 6 It is an integrated bonding of the pressure-sensitive layer and the photolithographic polyimide sheet.

[0028] Figure 7 The sensor encapsulation is completed by spin-coating high-temperature resistant rubber.

[0029] Figure 8 Anisotropic conductive adhesive is used to connect the printed circuit board and the sensor pads.

[0030] Figure 9 This is a schematic diagram of the three-dimensional structure of a flexible thin-film array sensor based on alveolar biomimetic structure; Figure 10 It is the dynamic response waveform of the sensor in the 10-25kHz range; Figure 10 (a) in the figure represents the voltage output signal of the sensing unit when following a 10kHz vibration. Figure 10 (b) in the figure represents the voltage output signal of the sensing unit when following a 15kHz vibration. Figure 10 (c) in the figure represents the voltage output signal of the sensing unit when following a 20kHz vibration. Figure 10In the figure, (d) represents the voltage output signal of the sensing unit when following a 25kHz vibration.

[0031] In the figure: 1. Polyimide film; 2. Glass sheet; 3. Metal film; 31. Metal film patterning; 4. Photoresist; 5. Photolithographic polyimide; 6. Flexible pressure-sensitive layer with microstructure; 7. High-temperature resistant rubber; 8. Printed circuit board; 9. Anisotropic conductive adhesive. Detailed Implementation

[0032] The embodiments of the present invention will be described in detail below with reference to the technical solutions and accompanying drawings.

[0033] As attached Figures 1-10 As shown in the figure, this embodiment provides a method for fabricating a high-frequency dynamic response flexible thin-film array sensor based on an alveolar biomimetic structure as follows: Step 1) As attached Figure 1 and Figure 2 As shown, a polyimide film 1 was spin-coated onto glass slide 2 (600 rpm, 9 s; high-speed 2500 rpm, 30 s) and cured by heating using a stepped heating strategy with the following parameters: 60℃, 10 min; 80℃, 10 min; 100℃, 10 min; 120℃, 10 min; 140℃, 10 min; 160℃, 10 min; 180℃, 10 min; 200℃, 10 min; 220℃, 10 min). A 100 nm thick metal film (Au) 2 was sputtered onto the surface of the 20 µm thick polyimide film 1 using magnetron sputtering.

[0034] Step 2) As attached Figure 3 As shown, a layer of photoresist 4 (AZ703) was spin-coated onto the surface of the metal thin film 2. The spin-coating parameters were low speed (600 rpm, 9 s) and high speed (2500 rpm, 30 s). The spin-coated photoresist substrate was pre-baked (85℃, 20 min). The photoresist 3 was then exposed and patterned using a UV lithography machine with an exposure time of 102.9 s and a light intensity of 3.4 mW / cm². 2 The photoresist substrate was then developed in a 25% AZ400K solution for 30 seconds. Following this, a gold etching solution (I2:KI:H2O = 1g:5g:50mL) was used to remove the unprotected metal film 2. The etching time was 30 seconds. The substrate was then rinsed with deionized water. Finally, the photoresist substrate was immersed in acetone solution for 30 seconds to remove the surface photoresist and then rinsed with ethanol to form a patterned metal film substrate.

[0035] Step 3) As attached Figure 4As shown, a layer of photolithographic polyimide 5 was spin-coated onto the surface of a metal thin film patterned substrate. The spin-coating parameters were low speed (600 rpm, 9 s) and high speed (3000 rpm, 30 s). The spin-coated photolithographic polyimide wafer was then pre-baked (85℃, 20 min). The photolithographic polyimide 5 was then exposed and patterned using a UV lithography machine with an exposure time of 88 s and a light intensity of 3.4 mW / cm². 2 The substrate was then placed in RS120 solution as a developer to remove unexposed photolithographic polyimide for 120 seconds, followed by 10 seconds of setting with PEGMA solution. The entire substrate was then cleaned with ethanol. Finally, the entire substrate was placed in an oven to imidize the photolithographic polyimide 5 using a stepped heating strategy with the following parameters: 60℃, 10 min; 80℃, 10 min; 100℃, 10 min; 120℃, 10 min; 140℃, 10 min; 160℃, 10 min; 180℃, 10 min; 200℃, 10 min; 220℃, 10 min.

[0036] Step 4) As attached Figure 5 As shown, inspired by the multi-level fractal structure of alveoli (primary vesicle - secondary microvesicles), a biomimetic patterned resin mold was designed with multiple grooves, consisting of an alternating array of deep and shallow grooves, to form a microstructure for a flexible pressure-sensitive layer. The microstructure is designed as a two-gradient semi-ellipsoidal structure, with the major axis ratio of the first gradient semi-ellipsoidal structure being 1:2, the midaxis ratio being 1:2, and the minor axis ratio being 1:2. The preparation process is as follows: 0.2g of conductive carbon nanotubes and 5g of high-temperature resistant silicone rubber GD401 were added to a beaker containing 25mL of volatile solvent naphtha Zippo 355 PJD1. The beaker was heated (40℃, 6h) using a magnetic stirrer (800rpm) and thoroughly stirred to form a conductive nanocomposite solution. A biomimetic patterned resin mold was printed using a high-precision 3D printer (MicroArch S230). A release agent was sprayed onto the surface of the mold, and then the prepared conductive nanocomposite solution was spin-coated onto the resin mold (low speed 600rpm, 9s; high speed 1000rpm, 30s). After the conductive nanocomposite solution was allowed to stand at room temperature for 24 hours to cure and demold, a flexible pressure-sensitive layer 6 containing microstructures was formed.

[0037] Step 5) As attached Figure 6As shown, a conductive nanocomposite solution is prepared in step 4 and spin-coated (low speed 600 rpm, 9 s; high speed 1500 rpm, 30 s) onto a clean glass slide. Then, the conductive nanocomposite solution glass slide is attached to the surface with the microstructure end of the flexible pressure-sensitive layer 6 facing the surface, so that the uncured conductive nanocomposite solution is attached to the tip of the microstructure of the flexible pressure-sensitive layer. Finally, the entire flexible pressure-sensitive layer and the interdigitated electrode area corresponding to the photolithographic polyimide substrate are integrally bonded.

[0038] Step 6) As attached Figure 7 As shown, high-temperature resistant silicone rubber 7 (JB 505) is prepared with a matrix and curing agent ratio of 10:1, with 10 mL and 1 mL of solution respectively. After mixing and cross-linking for 2 minutes, the mixture is placed in a vacuum oven and vacuumed for 10 minutes. Then, blue film tape is used to protect the area except for the flexible pressure-sensitive layer 6 containing microstructures. The high-temperature resistant silicone rubber 7 solution is spin-coated onto the entire surface of the flexible pressure-sensitive layer. After removing the blue film, the flexible piezoresistive sensor is encapsulated. Finally, the sensor is cut to the size that meets the application requirements.

[0039] Step 7) As attached Figure 8 As shown, anisotropic conductive adhesive is used to hot-press (150°C, 15s) the externally processed printed circuit board 8 and the electrode pad area of ​​the flexible thin film array sensor for alignment and bonding. The area of ​​the anisotropic conductive adhesive is cut to be the same as the pad area of ​​the flexible thin film array sensor.

[0040] Figure 9 A three-dimensional structural diagram of a flexible thin-film array sensor based on alveolar biomimetic structure is shown. Specifically, from bottom to top: a metal thin-film patterned substrate, a patterned photolithographic polyimide film 5, a flexible pressure-sensitive layer with microstructure made of conductive nanocomposite material 6 and a high-temperature resistant rubber encapsulation layer 7 on the upper left, an anisotropic conductive adhesive 9 and a printed circuit board 8 on the upper right.

[0041] Figure 10 This refers to the dynamic response performance of the sensor under high-frequency excitation. The specific test procedure is as follows: A piezoelectric ceramic is attached to the lower surface of the sensor. The piezoelectric ceramic and sensor are coaxially positioned and fixed using a special fixture on a universal testing machine, ensuring tight contact and uniform force. A high-frequency electrical signal of a preset frequency is generated by a signal generator as the excitation source. This excitation signal is amplified by a power amplifier and applied to the piezoelectric ceramic, causing it to vibrate at the corresponding frequency, thus providing high-frequency excitation to the sensor. Simultaneously, a complete test circuit is constructed using a custom-designed printed circuit board and a stable voltage supply. A multi-channel data acquisition system synchronously acquires the sensor's output electrical signal under excitation to accurately obtain its dynamic response data. Figure 10(a) When an excitation signal with a frequency of 10 kHz is applied to the sensor, the voltage signal waveform output by the sensor is consistent with the frequency of the excitation signal, demonstrating good response consistency. Figure 10 (b) is the output voltage signal waveform of the sensor when the excitation signal frequency is increased to 15kHz. The output signal can still accurately follow the excitation signal frequency, and the signal amplitude is stable without noise interference. Figure 10 (c) In the test scenario where the excitation signal frequency is 20kHz, the frequency of the sensor output voltage signal is synchronized with the excitation frequency and the waveform is regular, indicating that it still has reliable response performance at this frequency. Figure 10 (d) shows the output voltage signal waveform when the excitation signal frequency reaches 25kHz. The sensor can still accurately capture the excitation signal frequency and output the corresponding electrical signal without frequency shift or signal attenuation. In summary, within the high-frequency excitation range of 10kHz to 25kHz, the frequency of the sensor's output voltage signal always maintains a precise match with the excitation signal frequency, and the output waveform is stable with low distortion. This fully demonstrates that the sensor has excellent high-frequency tracking capability and can achieve accurate and stable response to high-frequency excitation signals.

[0042] The above-described embodiments are merely illustrative of the implementation methods of the present invention, but should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the protection scope of the present invention.

Claims

1. A method for fabricating a high-frequency dynamic response flexible thin-film array sensor based on alveolar biomimetic structures, characterized in that, The preparation method includes the following steps: Step 1: Spin-coat a flexible polymer substrate onto a glass slide and cure it. Then, deposit a metal film on the surface of the flexible polymer using a thin film deposition method. Step 2: Spin-coat a layer of photoresist film onto the surface of the metal film. Ultraviolet light is irradiated onto the substrate surface with the photoresist film through a mask. After development, the metal film is patterned. Then, the surface photoresist is removed to achieve the patterning of the photoresist and the metal film. Step 3: Spin-coat a photolithographic polyimide film onto the substrate surface patterned in Step 2. Perform photolithography on the substrate surface with the photolithographic polyimide film. After development and shaping, only the interdigitated electrode area and electrode pad area are exposed. Finally, cure the polyimide. Step 4: Prepare conductive nanocomposite solution by one-pot method, spin-coat the conductive nanocomposite solution onto the 3D printed biomimetic patterned resin mold, and form a flexible pressure-sensitive layer with microstructure after the conductive nanocomposite solution is cured and demolded. The biomimetic patterned resin mold has multiple grooves, which are formed by alternating arrays of deep and shallow grooves to form the microstructure of the flexible pressure-sensitive layer. The flexible pressure-sensitive layer containing the microstructure is designed as a semi-ellipsoidal structure with two gradients. The first gradient semi-ellipsoidal structure is formed corresponding to the deep groove at the bottom of the mold, and the second gradient semi-ellipsoidal structure is formed corresponding to the shallow groove at the bottom of the mold. Step 5: Integrate and bond the flexible pressure-sensitive layer obtained in Step 4 and the metal-film-patterned flexible polymer substrate obtained in Step 3. Step 6: Spin-coat high-temperature resistant silicone rubber onto the entire surface of the flexible piezoresistive layer to complete the encapsulation of the flexible piezoresistive sensor and obtain a flexible thin-film array sensor. Step 7: Use anisotropic conductive adhesive to hot-press and align the externally processed flexible printed circuit board and the electrode pad area of ​​the flexible thin film array sensor. The area of ​​the anisotropic conductive adhesive is cut to be the same as the pad area of ​​the flexible thin film array sensor.

2. The method for fabricating a high-frequency dynamic response flexible thin-film array sensor based on alveolar biomimetic structure according to claim 1, characterized in that, In step 1, the flexible polymer substrate is polyimide, and the metal film is gold; the film deposition method is magnetron sputtering.

3. The method for fabricating a high-frequency dynamic response flexible thin-film array sensor based on alveolar biomimetic structure according to claim 2, characterized in that, In step 2, the metal thin film patterning method is a standard photolithography process and wet etching; specifically: Ultraviolet lithography is used to irradiate the surface of a substrate with a photoresist film through a mask, so that the photoresist on the surface of the flexible polymer is patterned. The exposed photoresist is removed, and the unexposed photoresist at this time serves as a protective layer in the subsequent etching process. A gold etching solution is used to remove the metal film without photoresist protection. Finally, the surface photoresist is removed to obtain a patterned electrode pattern with a polyimide substrate. The photoresist is AZ703 positive photoresist; the gold etching solution is prepared from water, I2 and KI, wherein 1g of I2 and 1g of KI are added to every 50mL of H2O.

4. The method for fabricating a high-frequency dynamic response flexible thin-film array sensor based on alveolar biomimetic structure according to claim 3, characterized in that, The photolithographic polyimide patterning method in step 3 is a standard photolithography process and wet etching; specifically: The ultraviolet lithography machine uses a chromium plate to irradiate the surface of a substrate with a photolithographic thin film, which patterns the photoresist on the surface of the flexible polymer, removes the unexposed photolithographic polyimide, and sets the shape. Finally, the patterned polyimide is placed in an oven to cure. The photolithographic polyimide is BL301 negative photolithographic polyimide.

5. The method for fabricating a high-frequency dynamic response flexible thin-film array sensor based on alveolar biomimetic structure according to claim 4, characterized in that, In step 4, the one-pot method involves adding conductive nanomaterials and high-temperature resistant silicone rubber to a volatile solvent, heating and magnetically stirring to fully disperse the conductive nanomaterials in the mixture solution, forming a nanocomposite solution, and then performing post-treatment to obtain a conductive nanocomposite solution.

6. The method for fabricating a high-frequency dynamic response flexible thin-film array sensor based on alveolar biomimetic structure according to claim 5, characterized in that, In step 4: The ratio of the major axis of the first gradient semi-ellipsoidal structure to the minor axis of the second gradient semi-ellipsoidal structure is 1:(1.5~2.5), the ratio of the middle axis is 1:(1.5~2.5), and the ratio of the minor axis is 1:(1.5~2.5); the ratio of the major axis, the middle axis, and the minor axis are preferably all 1:2; The conductive nanomaterial is carbon nanotube with a diameter of 5-15 nm and a length of 10-30 μm; the high-temperature resistant silicone rubber is silicone rubber GD401; the volatile solvent is naphtha; 0.15-0.25 g of conductive nanomaterial and 4-6 g of high-temperature resistant silicone rubber are added for every 20 ml of volatile solvent. Before spin-coating the conductive nanocomposite solution onto the surface of the biomimetic patterned resin mold, a layer of release agent is sprayed onto the surface of the biomimetic patterned resin mold, with each 1cm layer containing a layer of release agent. 2 1 mL of conductive nanocomposite solution was spin-coated onto the surface of the biomimetic patterned resin mold.

7. The method for fabricating a high-frequency dynamic response flexible thin-film array sensor based on alveolar biomimetic structure according to claim 6, characterized in that, In step 5: The prepared conductive nanocomposite solution is rotated at high speed on a glass slide. The tip of the flexible pressure-sensitive layer containing microstructure after demolding in step 4 is attached to the surface of the glass slide containing a thin layer of conductive nanocomposite material, so that a layer of conductive nanocomposite solution adheres to the tip of the microstructure. The flexible pressure-sensitive layer and the interdigitated electrode area of ​​the flexible polymer substrate with metal thin film pattern are integrated and bonded together.

8. The method for fabricating a high-frequency dynamic response flexible thin-film array sensor based on alveolar biomimetic structure according to claim 7, characterized in that, In step 6: After crosslinking the matrix and curing agent at a mass ratio of 10:1, high-temperature resistant silicone rubber is obtained. It is then placed in a vacuum oven and vacuumed. Blue film tape is used to protect the area except for the pressure-sensitive layer. The high-temperature resistant silicone rubber is then spin-coated onto the entire surface of the flexible pressure-sensitive layer. After removing the blue film tape, the flexible piezoresistive sensor is encapsulated. The flexible piezoresistive sensor is then cut as needed.

9. A high-frequency dynamic response flexible thin-film array sensor based on alveolar biomimetic structure, characterized in that, The flexible piezoresistive sensor, prepared by any one of the preparation methods described in claims 1-8, can achieve a high degree of integration of the sensing unit, seamlessly attach to the inner wall of a complex curvature casing, and realize in-situ high-fidelity capture of the spatiotemporal distribution of wind pressure in high-temperature, strong-vibration, and confined-space environments.

10. The application of a high-frequency dynamic response flexible thin-film array sensor based on an alveolar biomimetic structure according to claim 9, characterized in that, It is seamlessly attached to the inner wall of the complex curvature casing to enable monitoring of the internal pressure of the turbofan engine compressor and periodic frequency response detection of the fan blades each time they pass the sensor.

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