Membrane type pressure sensor for monitoring cun-guan-chi pulse in traditional Chinese medicine pulse feeling and preparation method of membrane type pressure sensor

Abstract

The invention provides a film type pressure sensor for monitoring cun-guan-chi pulses in traditional Chinese medicine pulse feeling and a preparation method thereof, and relates to the technical field of traditional Chinese medicine. The patterned silver electrode can directly correspond to three pulse areas of cun, guan and chi, independent acquisition of signals of the three parts is realized, and signal confusion caused by the fact that a traditional sensor cannot be partitioned is avoided; the patterned gasket layer can provide stable support for the piezoresistive layer, ensure accurate and reliable contact between the piezoresistive layer and the three electrode areas, and reduce interlayer interference. The multi-layer structure works cooperatively, the bottom-layer base material and the top-layer base material are guaranteed to be flexibly attached to the wrist, electric signals can be accurately output through the silver electrodes according to resistance changes of the piezoresistive layer after the piezoresistive layer is pressed, accurate monitoring of cun-guan-chi pulse pressure is achieved, and reliable support is provided for objectification of traditional Chinese medicine pulse diagnosis.

Description

Technical Field

[0001] This invention relates to the field of traditional Chinese medicine technology, and more specifically, to a thin-film pressure sensor for monitoring the three pulses (cun, guan, chi) in traditional Chinese medicine pulse diagnosis and its preparation method. Background Technology

[0002] Traditional Chinese medicine pulse diagnosis is a core method of "integrating the four diagnostic methods". Physicians judge health status by sensing the pulse characteristics of the radial artery at the cun, guan, and chi positions. However, traditional pulse diagnosis relies on subjective experience, lacks quantitative indicators, and has poor repeatability, which restricts the promotion of the modernization of traditional Chinese medicine. Developing a thin-film pressure sensor that can accurately collect cun, guan, and chi pulse signals has become crucial.

[0003] While existing thin-film pressure sensors offer advantages such as flexibility and compactness, they fall short of pulse diagnosis requirements and exhibit significant technical limitations.

[0004] The performance of the piezoresistive slurry is insufficient and its adaptability is poor: the traditional carbon slurry used is unevenly dispersed and lacks elastic matrix for coordinated control. The initial resistance of the pressure point is low and the range is narrow, which cannot cover the pressure range required for "floating, mid-range and sinking". After curing, the structure is rigid and has poor resilience. The signal lags after being pressed and cannot quickly rebound to the baseline. It is easy to lose the dynamic characteristics of the pulse (such as rhythm and strength changes), resulting in data deviation.

[0005] The manufacturing process is complex and mass production is difficult: the key layers (silver electrode layer and piezoresistive layer) mostly rely on vacuum processes such as evaporation and sputtering or laser cutting after coating, which are cumbersome and costly; the silver electrode pattern has low precision and is difficult to align precisely with the dimensions, which can easily lead to poor contact; the piezoresistive layer has uneven thickness, resulting in large differences in sensitivity during mass production, poor performance consistency, and low efficiency, which cannot meet the needs of large-scale production.

[0006] Poor structural design adaptability and unstable signal: The structure is not optimized for pulse diagnosis, the layout of pressure points does not match the physiological positions of Cun, Guan and Chi (linear distribution with a spacing of 1-2cm), does not conform to the habit of "three-finger positioning", and the signal is difficult to correspond to the pulse pattern of the region; there is often no dedicated pad layer or the pad material has insufficient insulation and mechanical strength, electrical interference is easy to occur between layers, and the contact between the piezoresistive layer and the electrode layer is unstable when pressure is applied, resulting in large signal fluctuations.

[0007] The aforementioned defects result in existing sensors having low accuracy, slow response, and poor adaptability, which cannot support the objectification of pulse diagnosis and restricts the digital development of TCM pulse diagnosis. There is an urgent need to develop thin-film pressure sensors with wide range, fast rebound, simple manufacturing process, and accurate alignment to break through the bottleneck. Summary of the Invention

[0008] To overcome the shortcomings of the prior art, the present invention provides a thin-film pressure sensor for monitoring the three pulses of Cun, Guan, and Chi in traditional Chinese medicine pulse diagnosis and a method for preparing the same.

[0009] This invention provides a thin-film pressure sensor for monitoring the three pulses (cun, guan, chi) in traditional Chinese medicine pulse diagnosis, comprising:

[0010] Underlying substrate layer;

[0011] A silver electrode layer is patterned on the underlying substrate layer, and the silver electrode layer includes three electrode regions corresponding to the positions of cun, guan, and chi.

[0012] A pad layer is patterned on the silver electrode layer;

[0013] A piezoresistive layer is disposed on the pad layer and makes corresponding contact with the three electrode regions of the silver electrode layer;

[0014] A top substrate layer is disposed on the piezoresistive layer;

[0015] The piezoresistive layer changes resistance under pressure, and outputs an electrical signal through the silver electrode layer, thereby monitoring the pulse pressure at the cun, guan, and chi positions.

[0016] Compared with existing technologies, the advantages of this thin-film pressure sensor are as follows: it accurately adapts to the pulse diagnosis needs of traditional Chinese medicine (TCM) at the cun, guan, and chi positions; the patterned silver electrodes can directly correspond to the three pulse regions of cun, guan, and chi, enabling independent signal acquisition from the three locations and avoiding signal confusion caused by the inability of traditional sensors to partition the pulses; the patterned pad layer provides stable support for the piezoresistive layer, ensuring accurate and reliable contact between the piezoresistive layer and the three electrode regions, reducing interlayer interference; the multi-layer structure works in synergy, with the bottom and top substrates ensuring a flexible fit to the wrist; the resistance change of the piezoresistive layer under pressure can be accurately output as an electrical signal through the silver electrodes, enabling precise monitoring of the cun, guan, and chi pulse pressure and providing reliable support for the objectification of TCM pulse diagnosis.

[0017] The second objective of this invention is to provide a method for fabricating a thin-film pressure sensor, the method specifically comprising the following steps:

[0018] S1. Flexible substrate is used as the raw material for the bottom substrate layer and the top substrate layer, and is prepared for use after cleaning.

[0019] S2. Using screen printing, silver electrode patterns are printed on the surface of the cleaned substrate layer with silver paste as the raw material, and then the silver electrode layer is obtained after a curing process.

[0020] S3. A gasket layer is prepared by printing patterned pressure-sensitive adhesive or by laser-cutting patterned PET double-sided adhesive and then aligning and attaching it between the silver electrode layer and the piezoresistive layer.

[0021] S4. The piezoresistive layer paste is printed on the surface of the top substrate layer using screen printing, and then three curing processes are performed.

[0022] S5. The top substrate layer with the printed piezoresistive layer is bonded to the bottom substrate above the gasket layer and silver electrode layer, ensuring that the piezoresistive layer makes corresponding contact with the silver electrode layer and the gasket layer. Compared with existing technologies, the preparation method used in this invention has significant advantages. The entire process utilizes screen printing, which is simple to operate and easily achieves patterned processing. It can precisely form the silver electrode, gasket layer, and piezoresistive layer, ensuring the matching degree of each functional layer with the corresponding dimensional structure. Substrate cleaning pretreatment removes impurities and improves interlayer adhesion; staged curing treatment allows each layer to fully cure, ensuring structural stability and reliable performance. The final precise bonding step ensures accurate contact between the piezoresistive layer and the silver electrode layer and gasket layer, avoiding poor contact problems. The overall process is coherent and efficient, facilitating mass production while ensuring the consistency and performance of the sensor.

[0023] In one possible implementation, the flexible substrate is made from a material selected from PET, PI, TPU, and printable fabrics. The present invention uses these materials as the flexible substrate because they offer excellent flexibility, allowing for a close fit to the wrist and ensuring accurate pulse signal acquisition; they are also heat-resistant, adaptable to the multi-step curing process during fabrication, and structurally stable, maintaining the sensor's long-term performance.

[0024] In one possible embodiment, the pressure resist layer slurry is composed of the following components: 10-30 parts epoxy resin, 6.5-19.5 parts curing agent, 0.15-0.45 parts accelerator, 4-14 parts toner, 35-55 parts polyurethane slurry, 15-25 parts solvent, and 0.2-1 part dispersant.

[0025] The carbon powder is composed of beaded carbon black, sheet graphene powder and carbon nanotubes in a mass ratio of 2:1:2. The median particle size of the beaded carbon black is 25 nm, the median particle size of the sheet graphene powder is 5 μm, and the average diameter of the carbon nanotubes is 7-12 nm and the length is 50-250 μm.

[0026] Compared with existing technologies, the components of the piezoresistive layer slurry in this invention are synergistically adapted to the sensor requirements. The epoxy resin, combined with a curing agent and accelerator, ensures the stability of the piezoresistive layer structure. The toner, a mixture of conductive carbon black and graphite, ensures good piezoresistive characteristics for accurate response to pressure changes. The polyurethane slurry enhances the layer's resilience, and the solvent facilitates adjusting the slurry state for easy printing. The overall formulation allows the piezoresistive layer to possess both stable piezoresistive response and structural reliability, meeting the application requirements of pulse pressure monitoring.

[0027] In one possible implementation, the piezoresistive layer slurry is prepared by the following method:

[0028] A1. Raw material pretreatment and mixing: Weigh the epoxy resin, curing agent and accelerator according to the formula, stir evenly to obtain the resin system, then slowly add 3 / 5 of the total amount of carbon powder, stir evenly, add polyurethane slurry, stir evenly, then add the remaining 2 / 5 of the carbon powder and 1 / 2 of the total amount of solvent, stir evenly to form a preliminary mixed slurry.

[0029] A2. Ball milling dispersion: The initially mixed slurry is ball milled with stainless steel ball milling beads, and then the remaining 1 / 2 of the solvent is added and the ball milling process is continued to adjust the slurry viscosity to 40000 cP.

[0030] A3. Filtration and Homogenization / Defoaming: After filtering the slurry, homogenization and defoaming treatment are performed.

[0031] A4. Three-roll milling: The slurry is fed into a three-roll mill for grinding.

[0032] A5. Mixing treatment: The slurry after grinding is mixed again;

[0033] A6. Second homogenization and defoaming: The pressure resistance layer slurry is obtained by homogenizing and defoaming again.

[0034] Compared with existing technologies, this preparation method can fully disperse raw materials and avoid particle agglomeration by adding carbon powder and solvent in steps, combined with ball milling and three-roll milling; filtration and two homogenization and defoaming can remove impurities and air bubbles, ensuring the purity of the slurry; the overall process makes the slurry uniformly dispersed and stable, and the resulting piezoresistive layer is suitable for printing processes, and its rebound and piezoresistive response are reliable, which can meet the needs of pulse monitoring.

[0035] This carbon paste uses epoxy resin and polyurethane as the composite matrix, combined with 25nm beaded carbon black, 5μm sheet graphene, and 7-12nm×50-250μm carbon nanotubes in a 2:1:2 mass ratio to construct an "elastic matrix + multi-level conductive network" structure, suitable for the pulse detection requirements of Cun, Guan, and Chi positions: In terms of resilience, polyurethane (recovery ≤50ms) and epoxy resin work synergistically, and the carbon material fills the gaps to maintain conductivity, with an elastic recovery rate ≥98%. After being compressed, it returns to zero immediately upon release, with no static residual signal, accurately restoring the pulse waveform with a period of 0.8-1.2s and a deformation of 5-10μm; in terms of sensitivity, the carbon nanotubes form a through-pathway, and the three components form a three-dimensional network, achieving a sensitivity of 50-100kPa. -1 It can capture pressure differences of 0.2-0.5 kPa at the cun, guan, and chi positions, with a pulse wave feature recognition rate of ≥95%; its four-dimensional collaborative performance provides core material support for high-precision pulse monitoring.

[0036] In one possible implementation, in step S1, the cleaning process includes wiping the substrate surface with anhydrous ethanol and drying it at 100-130°C for 30 minutes. Wiping with anhydrous ethanol can remove oil and impurities from the substrate surface, and subsequent drying can remove residual moisture, avoiding problems such as bubbles and poor adhesion during subsequent printing, thus laying the foundation for accurate bonding of each functional layer and stable operation of the sensor.

[0037] In one possible implementation, the parameters of the screen printing method in steps S2, S3 and S4 are as follows: using a 100-350 mesh polyester screen, a squeegee hardness of 70 Shore A, a squeegee pressure of 0.3-0.4 MPa, a printing speed of 30-40 mm / s, a screen distance of 1.5 mm, and a wet film thickness of 20-30 μm.

[0038] Compared with existing technologies, the screen printing parameters used in this invention are reasonably matched, which can ensure that the printed patterns of the silver electrode layer, pad layer and piezoresistive layer are accurate and clear, and the thickness is uniform. It can also make each functional layer fit tightly with the substrate and adjacent layers, reducing defects such as bubbles and misalignment, laying the foundation for accurate correspondence of each layer and stable transmission of pulse pressure signals by the sensor.

[0039] In one possible implementation, the primary curing process in step S2 includes: pre-drying at 60-80°C for 10 minutes, followed by curing at 120-150°C for 30-60 minutes. The pre-drying process removes solvents from the silver paste, preventing bubbles or layer cracking during subsequent high-temperature curing. The high-temperature curing then ensures a stable silver electrode layer structure, strong adhesion, and excellent conductivity, guaranteeing reliable operation and adaptability to subsequent process requirements.

[0040] In one possible implementation, the secondary curing process in step S3 is carried out at 100-120°C for 40-50 minutes. The secondary curing parameters are adapted to the gasket layer material, allowing it to fully cure and form a stable structure. This ensures insulation performance to isolate interlayer interference and enhances adhesion to the silver electrode layer, providing reliable support for the piezoresistive layer and ensuring interlayer stability of the sensor.

[0041] In one possible implementation, the three curing processes in step S4 include: first pre-baking at 50-60℃ for 10-20 min, then holding at 80-100℃ for 10 min, and finally curing at 100-130℃ for 30 min, wherein the heating rate is 4-5℃ / min.

[0042] Compared with existing technologies, the present invention performs three stages of curing, combined with slow heating, which can gradually remove the solvent in the piezoresistive layer slurry and avoid rapid curing that can cause bubbles or cracks. The temperature of each stage is adapted to the material characteristics, which can fully cure the piezoresistive layer, ensuring structural stability, strong adhesion to the gasket layer, and good piezoresistive response and resilience, thus meeting the needs of pulse pressure monitoring. Attached Figure Description

[0043] Figure 1 This is a schematic cross-sectional view of the thin-film pressure sensor of the present invention.

[0044] Figure 2 This is a plan view of the thin-film pressure sensor of the present invention;

[0045] Figure 3 The graph shows the stepped pressure-step resistance characteristic curve of the thin-film pressure sensor prepared in Example 1.

[0046] Figure 4 The graph shows the resistance stability test of the thin-film pressure sensor prepared in Example 1 under the same pressure.

[0047] Figure 5 This is a wrist pulse signal detection diagram of the thin-film pressure sensor prepared in Example 1.

[0048] Explanation of reference numerals in the attached figures: 100, bottom substrate layer; 101, silver electrode layer; 102, electrode area; 103, gasket layer; 104, piezoresistive layer; 105, top substrate layer. Detailed Implementation

[0049] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described in detail below. It should be noted that the following embodiments are only used to illustrate the implementation methods and typical parameters of the present invention, and are not intended to limit the parameter range described in the present invention. Reasonable variations derived therefrom are still within the protection scope of the present invention.

[0050] It should be noted that the endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0051] Unless otherwise defined, all terms, symbols, and other scientific terms used herein are intended to have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In some instances, terms having a conventional meaning are defined herein for clarification or ease of reference, and such definitions should not be construed as indicating a significant difference from conventional understanding in the art. The technical methods described or referenced herein are generally well understood by those skilled in the art and employed by conventional methods. Unless otherwise stated, the use of commercially available kits, reagents, and instruments shall be performed according to the manufacturer's instructions and parameters.

[0052] A specific embodiment of the present invention provides a thin-film pressure sensor for monitoring the three pulses (cun, guan, chi) in traditional Chinese medicine pulse diagnosis, comprising:

[0053] The bottom substrate layer is 100;

[0054] A silver electrode layer 101 is patterned on the underlying substrate layer 100. The silver electrode layer 101 includes three electrode regions 102 corresponding to the positions of cun, guan, and chi.

[0055] The pad layer 103 is patterned on the silver electrode layer 101;

[0056] Piezoresistive layer 104 is disposed on pad layer 103 and is in contact with the three electrode regions 102 of silver electrode layer 101.

[0057] The top substrate layer 105 is disposed on the piezoresistive layer 104;

[0058] The piezoresistive layer 104 changes its resistance under pressure, and outputs an electrical signal through the silver electrode layer 101, thereby monitoring the pulse pressure at the cun, guan, and chi positions.

[0059] The present invention also provides a method for fabricating a thin-film pressure sensor, the method comprising the following steps:

[0060] S1. Using polyimide film as the raw material for the bottom substrate layer 100 and the top substrate layer 105, the substrate surface is wiped with anhydrous ethanol and dried at 100-130℃ for 30 minutes before use.

[0061] S2. Using screen printing, silver electrode patterns are printed on the surface of the cleaned substrate layer 100 using silver paste as raw material. Then, the substrate is pre-dried at 60-80℃ for 10 minutes and then cured at 120-150℃ for 30-60 minutes to obtain the silver electrode layer 101.

[0062] S3. The gasket layer 103 is prepared by printing patterned pressure-sensitive adhesive or by laser-cutting patterned PET double-sided adhesive and then aligning and attaching it between the silver electrode layer 101 and the piezoresistive layer 104.

[0063] S4. The piezoresistive layer 104 paste is printed on the surface of the top substrate layer 105 using screen printing, and then three curing processes are performed.

[0064] The carbon powder is composed of beaded carbon black, sheet graphene powder, and carbon nanotubes in a mass ratio of 2:1:2. The median particle size of the beaded carbon black is 25 nm, the median particle size of the sheet graphene powder is 5 μm, and the average diameter of the carbon nanotubes is 7-12 nm and the length is 50-250 μm. The three-stage curing process includes: pre-baking at 50-60℃ for 10-20 min, holding at 80-100℃ for 10 min, and finally curing at 100-130℃ for 30 min, with a heating rate of 4-5℃ / min. The epoxy resin is a thermosetting epoxy resin, and the curing agent is an acid anhydride curing agent.

[0065] S5. Precisely attach the top substrate to the bottom substrate so that the piezoresistive layer 104 makes corresponding contact with the silver electrode layer 101 and the pad layer 103.

[0066] It is worth mentioning that the parameters of the screen printing method in steps S2, S3 and S4 are as follows: using a 100-350 mesh polyester screen, a squeegee hardness of 70 Shore A, a squeegee pressure of 0.3-0.4 MPa, a printing speed of 30-40 mm / s, a screen distance of 1.5 mm, and a wet film thickness of 20-30 μm.

[0067] In step S4, the piezoresistive layer 104 slurry is prepared by the following method:

[0068] A1. Raw material pretreatment and mixing: Weigh the epoxy resin, curing agent and accelerator according to the formula, stir evenly to obtain the resin system, then slowly add 3 / 5 of the total amount of carbon powder, stir evenly, add polyurethane slurry, stir evenly, then add the remaining 2 / 5 of the carbon powder and 1 / 2 of the total amount of solvent, stir evenly to form a preliminary mixed slurry.

[0069] A2. Ball milling dispersion: The initially mixed slurry is ball milled with stainless steel ball milling beads, and then the remaining 1 / 2 of the solvent is added and the ball milling process is continued to adjust the slurry viscosity to 40000 cP.

[0070] A3. Filtration and Homogenization / Defoaming: After filtering the slurry, homogenization and defoaming treatment are performed.

[0071] A4. Three-roll milling: The slurry is fed into a three-roll mill for grinding.

[0072] A5. Mixing treatment: The slurry after grinding is mixed again;

[0073] A6. Second homogenization and defoaming: A second homogenization and defoaming process is performed to obtain the pressure resistance layer slurry.

[0074] More specifically, the piezoresistive layer 104 slurry can be prepared by the following method:

[0075] B1. Prepare the following raw materials: 10-30 parts epoxy resin, 6.5-19.5 parts curing agent, 0.15-0.45 parts accelerator, 4-14 parts toner, 35-55 parts polyurethane slurry, 15-25 parts solvent, and 0.2-1 parts dispersant.

[0076] B2. Weigh the epoxy resin, curing agent and accelerator, place them in a stainless steel mixing container, start the mixing equipment, and stir at 900 r / min for 30 minutes at room temperature of 25℃ until the materials are completely dissolved and a uniform and transparent resin system is formed.

[0077] B3. Then, slowly add 60wt% toner to the resin system while stirring (keeping the stirring speed at 600 rpm). Control the addition time within 10 minutes to ensure uniform dispersion of the toner and avoid agglomeration. After the toner is evenly dispersed, add the pre-dissolved polyurethane slurry to the system, adjust the stirring speed to 1200 rpm, and continue stirring for 30 minutes to fully integrate the elastic matrix with the resin and toner. Add the remaining toner while stirring (600 rpm). Add 50wt% of 51 solvent, adjust the stirring speed to 800 rpm, and continue stirring for 1 hour to form a preliminary mixed slurry with a solid content of about 60%.

[0078] B4. Transfer all the initially mixed slurry to a stainless steel ball mill jar. Add stainless steel ball milling beads with a particle size gradient of 5mm, 3mm, and 1mm (mass ratio 2:2:1) at a slurry-to-milling-beads mass ratio of 1:3. Set the rotation speed to 5000r / min and start the equipment for ball milling for 30 minutes. The carbon powder is then dispersed secondaryly through high-energy collision. After 30 minutes of ball milling, slowly add the remaining 51 solvent to the ball mill jar and continue ball milling at 5000r / min for 10 minutes. Adjust the slurry viscosity to 40000cP (25℃). After ball milling, filter the slurry through a 200-mesh nylon screen to remove the ball milling beads and large particle impurities. Collect the filtered, uniform slurry.

[0079] B5. Transfer the filtered slurry to a vacuum homogenizer and defoamer. Set the vacuum level to -0.09MPa and the rotation speed to 1500r / min for homogenization and defoaming treatment for 10 minutes to remove air bubbles from the slurry. After homogenization and defoaming, send the slurry to a three-roll mill for fine grinding. For the first grinding, set the feed roller spacing of the three-roll mill to 70μm and the discharge roller spacing to 35μm, and control the slurry feed speed to 5L / h. Pass the slurry through the rollers twice according to these parameters to reduce the particle agglomeration size.

[0080] B6. After the three-roll milling is completed, the slurry is collected and transferred to a mixing container. The mixing speed is controlled at 800 r / min and the mixing is continued for 1 hour. After the mixing is completed, the slurry is transferred to a homogenizer and defoamer again. It is treated at 1500 r / min speed and -0.09 MPa vacuum for 10 minutes to finally obtain a uniformly dispersed, bubble-free, and viscosity-stable pressure resistance layer 104 slurry.

[0081] The solvent is 51 solvent, which is a mixture of ethylene glycol butyl ether, ethylene glycol butyl ether acetate, dipropylene glycol methyl ether, diethylene glycol butyl ether and diethylene glycol butyl ether acetate in a mass ratio of 1:1:1:1:1.

[0082] The polyurethane slurry is formulated from 15.6 wt% isophorone, 22 wt% 5836 type PU (PU granules purchased from Dongguan Jiurui Plastic Raw Materials Co., Ltd.), and 62.4 wt% DBE. The specific steps include: first, stirring isophorone and DBE at 500 r / min for 1 min, then heating to 47°C, adding 5836 type PU and performing gradient mechanical stirring, successively stirring at 550 r / min for 15 min, 820 r / min for 10 min, 1280 r / min for 25 min, and finally stirring at 1420 r / min for 35 min.

[0083] The detection method of this invention is described in detail below:

[0084] Viscosity: The viscosity was measured using a viscometer at a temperature of 25 degrees Celsius and a rotation speed of 50 rpm. The viscometer was manufactured by Shanghai Fangrui Instrument Co., Ltd.

[0085] Sheet resistance: tested using a handheld four-probe tester manufactured by Suzhou Jingge Electronics Co., Ltd.

[0086] Adhesion: Using the cross-cut adhesion test standard, apply transparent tape to the cut edge of the coating, peel off the tape evenly, and check the damage to the cut coating. If there is no peeling or chipping, and the edges are neat, it is 5B.

[0087] Example 1

[0088] This embodiment provides a thin-film pressure sensor for monitoring the three pulses (cun, guan, chi) in traditional Chinese medicine pulse diagnosis, including:

[0089] The bottom substrate layer is 100;

[0090] A silver electrode layer 101 is patterned on the underlying substrate layer 100. The silver electrode layer 101 includes three electrode regions 102 corresponding to the positions of cun, guan, and chi.

[0091] The pad layer 103 is patterned on the silver electrode layer 101;

[0092] Piezoresistive layer 104 is disposed on pad layer 103 and is in contact with the three electrode regions 102 of silver electrode layer 101.

[0093] The top substrate layer 105 is disposed on the piezoresistive layer 104;

[0094] The piezoresistive layer 104 changes its resistance under pressure, and outputs an electrical signal through the silver electrode layer 101, thereby monitoring the pulse pressure at the cun, guan, and chi positions.

[0095] It was prepared by the following method:

[0096] S1. Using polyimide film as the raw material for the bottom substrate layer 100 and the top substrate layer 105, the substrate surface is wiped with anhydrous ethanol and dried at 100°C for 30 minutes before use.

[0097] S2. Using screen printing, silver electrode patterns are printed on the surface of the cleaned substrate layer 100 using silver paste as raw material. Then, the substrate is pre-dried at 60°C for 10 minutes and then cured at 120°C for 30 minutes to obtain the silver electrode layer 101.

[0098] S3. A gasket layer 103 is prepared by printing patterned pressure-sensitive adhesive or by laser-cutting patterned PET double-sided adhesive and then aligning and attaching it between the silver electrode layer 101 and the piezoresistive layer 104.

[0099] S4. The piezoresistive layer 104 paste is printed on the surface of the top substrate layer 105 using screen printing, and then subjected to three curing processes. The three curing processes include: pre-baking at 50℃ for 10 min, holding at 80℃ for 10 min, and finally curing at 100℃ for 30 min, with a heating rate of 4℃ / min. The epoxy resin is a thermosetting epoxy resin, and the curing agent is an acid anhydride curing agent.

[0100] S5. Precisely attach the top substrate to the bottom substrate so that the piezoresistive layer 104 makes corresponding contact with the silver electrode layer 101 and the pad layer 103.

[0101] It is worth mentioning that the parameters of the screen printing method in steps S2, S3 and S4 are as follows: a 300-mesh polyester screen is used, the squeegee hardness is 70 Shore A, the squeegee pressure is 0.3 MPa, the printing speed is 30 mm / s, the screen distance is 1.5 mm, and the wet film thickness is 20 μm.

[0102] The piezoresistive layer 104 slurry is prepared by the following method:

[0103] B1. Prepare the following raw materials: 12.9 parts epoxy resin, 8.4 parts curing agent, 0.2 parts accelerator, 5 parts toner, 51.7 parts polyurethane slurry, 19.4 parts solvent, and 0.6 parts toner stabilizer;

[0104] B2. Weigh the epoxy resin, curing agent and accelerator, place them in a stainless steel mixing container, start the mixing equipment, and stir at 900 r / min for 30 minutes at room temperature of 25℃ until the materials are completely dissolved and a uniform and transparent resin system is formed.

[0105] B3. Then, slowly add 60wt% toner to the resin system while stirring (keeping the stirring speed at 600 rpm). Control the addition time within 10 minutes to ensure uniform dispersion of the toner and avoid agglomeration. After the toner is evenly dispersed, add the pre-dissolved polyurethane slurry to the system, adjust the stirring speed to 1200 rpm, and continue stirring for 30 minutes to fully integrate the elastic matrix with the resin and toner. Add the remaining toner while stirring (600 rpm). Add 50wt% of 51 solvent, adjust the stirring speed to 800 rpm, and continue stirring for 1 hour to form a preliminary mixed slurry with a solid content of about 60%.

[0106] B4. Transfer all the initially mixed slurry to a stainless steel ball mill jar. Add stainless steel ball milling beads with a particle size gradient of 5mm, 3mm, and 1mm (mass ratio 2:2:1) at a slurry to ball milling bead mass ratio of 1:3. Set the rotation speed to 5000r / min and start the equipment for ball milling for 30 minutes. The carbon powder is then dispersed secondaryly through high-energy collision. After 30 minutes of ball milling, slowly add the remaining 51 solvent to the ball mill jar and continue ball milling at 5000r / min for 10 minutes. Adjust the slurry viscosity to 40000cP (25℃). After ball milling, filter the slurry through a 200-mesh nylon screen to remove the ball milling beads and large particle impurities. Collect the filtered uniform slurry.

[0107] B5. Transfer the filtered slurry to a vacuum homogenizer and defoamer. Set the vacuum level to -0.09MPa and the rotation speed to 1500r / min for homogenization and defoaming treatment for 10 minutes to remove air bubbles from the slurry. After homogenization and defoaming, send the slurry to a three-roll mill for fine grinding. For the first grinding, set the feed roller spacing of the three-roll mill to 70μm and the discharge roller spacing to 35μm, and control the slurry feed speed to 5L / h. Pass the slurry through the rollers twice according to these parameters to reduce the particle agglomeration size.

[0108] B6. After the three-roll milling is completed, the slurry is collected and transferred to a mixing container. The mixing speed is controlled at 800 r / min and the mixing is continued for 1 hour. After the mixing is completed, the slurry is transferred to a homogenizer and defoamer. It is treated at 1500 r / min speed and -0.09 MPa vacuum for 10 minutes to finally obtain a uniformly dispersed, bubble-free, and viscosity-stable high-resistance carbon paste for screen printing.

[0109] Example 2

[0110] This embodiment provides a thin-film pressure sensor for monitoring the three pulses (cun, guan, chi) in traditional Chinese medicine pulse diagnosis, including:

[0111] The bottom substrate layer is 100;

[0112] A silver electrode layer 101 is patterned on the underlying substrate layer 100. The silver electrode layer 101 includes three electrode regions 102 corresponding to the positions of cun, guan, and chi.

[0113] The pad layer 103 is patterned on the silver electrode layer 101;

[0114] Piezoresistive layer 104 is disposed on pad layer 103 and is in contact with the three electrode regions 102 of silver electrode layer 101.

[0115] The top substrate layer 105 is disposed on the piezoresistive layer 104;

[0116] The piezoresistive layer 104 changes its resistance under pressure, and outputs an electrical signal through the silver electrode layer 101, thereby monitoring the pulse pressure at the cun, guan, and chi positions.

[0117] It was prepared by the following method:

[0118] S1. Using polyimide film as the raw material for the bottom substrate layer 100 and the top substrate layer 105, the substrate surface is wiped with anhydrous ethanol and dried at 112°C for 30 minutes before use.

[0119] S2. Using screen printing, silver electrode patterns are printed on the surface of the cleaned substrate layer 100 using silver paste as raw material. Then, the substrate is pre-dried at 70°C for 10 min and cured at 135°C for 50 min to obtain the silver electrode layer 101.

[0120] S3. A gasket layer 103 is prepared by printing patterned pressure-sensitive adhesive or by laser-cutting patterned PET double-sided adhesive and then aligning and attaching it between the silver electrode layer 101 and the piezoresistive layer 104.

[0121] S4. The piezoresistive layer 104 paste is printed on the surface of the top substrate layer 105 using screen printing, and then subjected to three curing processes. The three curing processes include: pre-baking at 55℃ for 15 minutes, holding at 90℃ for 10 minutes, and finally curing at 120℃ for 30 minutes, with a heating rate of 4.5℃ / min. The epoxy resin is a thermosetting epoxy resin, and the curing agent is an acid anhydride curing agent.

[0122] S5. Precisely attach the top substrate to the bottom substrate so that the piezoresistive layer 104 makes corresponding contact with the silver electrode layer 101 and the pad layer 103.

[0123] It is worth mentioning that the parameters of the screen printing method in steps S2, S3 and S4 are as follows: a 300-mesh polyester screen is used, the squeegee hardness is 70 Shore A, the squeegee pressure is 0.35 MPa, the printing speed is 35 mm / s, the screen distance is 1.5 mm, and the wet film thickness is 25 μm.

[0124] The piezoresistive layer 104 slurry can be prepared by the following method:

[0125] B1. Prepare the following raw materials: 30 parts epoxy resin, 19.5 parts curing agent, 0.45 parts accelerator, 7 parts toner, 55 parts polyurethane slurry, 25 parts solvent, and 1 part toner stabilizer.

[0126] B2. Weigh the epoxy resin, curing agent and accelerator, place them in a stainless steel mixing container, start the mixing equipment, and stir at 900 r / min for 30 minutes at room temperature of 25℃ until the materials are completely dissolved and a uniform and transparent resin system is formed.

[0127] B3. Then, slowly add 60wt% toner to the resin system while stirring (keeping the stirring speed at 600 rpm). Control the addition time within 10 minutes to ensure uniform dispersion of the toner and avoid agglomeration. After the toner is evenly dispersed, add the pre-dissolved polyurethane slurry to the system, adjust the stirring speed to 1200 rpm, and continue stirring for 30 minutes to fully integrate the elastic matrix with the resin and toner. Add the remaining toner while stirring (600 rpm). Add 50wt% of 51 solvent, adjust the stirring speed to 800 rpm, and continue stirring for 1 hour to form a preliminary mixed slurry with a solid content of about 60%.

[0128] B4. Transfer all the initially mixed slurry to a stainless steel ball mill jar. Add stainless steel ball milling beads with a particle size gradient of 5mm, 3mm, and 1mm (mass ratio 2:2:1) at a slurry-to-milling-beads mass ratio of 1:3. Set the rotation speed to 5000r / min and start the equipment for ball milling for 30 minutes. The carbon powder is then dispersed secondaryly through high-energy collision. After 30 minutes of ball milling, slowly add the remaining 51 solvent to the ball mill jar and continue ball milling at 5000r / min for 10 minutes. Adjust the slurry viscosity to 40000cP (25℃). After ball milling, filter the slurry through a 200-mesh nylon screen to remove the ball milling beads and large particle impurities. Collect the filtered, uniform slurry.

[0129] B5. Transfer the filtered slurry to a vacuum homogenizer and defoamer. Set the vacuum level to -0.09MPa and the rotation speed to 1500r / min for homogenization and defoaming treatment for 10 minutes to remove air bubbles from the slurry. After homogenization and defoaming, send the slurry to a three-roll mill for fine grinding. For the first grinding, set the feed roller spacing of the three-roll mill to 70μm and the discharge roller spacing to 35μm, and control the slurry feed speed to 5L / h. Pass the slurry through the rollers twice according to these parameters to reduce the particle agglomeration size.

[0130] B6. After the three-roll milling is completed, the slurry is collected and transferred to a mixing container. The mixing speed is controlled at 800 r / min and the mixing is continued for 1 hour. After the mixing is completed, the slurry is transferred to a homogenizer and defoamer again. It is treated at 1500 r / min speed and -0.09 MPa vacuum for 10 minutes to finally obtain a uniformly dispersed, bubble-free, and viscosity-stable high-resistance carbon paste for screen printing.

[0131] Example 3

[0132] This embodiment provides a thin-film pressure sensor for monitoring the three pulses (cun, guan, chi) in traditional Chinese medicine pulse diagnosis, including:

[0133] The bottom substrate layer is 100;

[0134] A silver electrode layer 101 is patterned on the underlying substrate layer 100. The silver electrode layer 101 includes three electrode regions 102 corresponding to the positions of cun, guan, and chi.

[0135] The pad layer 103 is patterned on the silver electrode layer 101;

[0136] Piezoresistive layer 104 is disposed on pad layer 103 and is in contact with the three electrode regions 102 of silver electrode layer 101.

[0137] The top substrate layer 105 is disposed on the piezoresistive layer 104;

[0138] The piezoresistive layer 104 changes its resistance under pressure, and outputs an electrical signal through the silver electrode layer 101, thereby monitoring the pulse pressure at the cun, guan, and chi positions.

[0139] It was prepared by the following method:

[0140] S1. Using polyimide film as the raw material for the bottom substrate layer 100 and the top substrate layer 105, the substrate surface is wiped with anhydrous ethanol and dried at 130°C for 30 minutes before use.

[0141] S2. Using screen printing, silver electrode patterns are printed on the surface of the cleaned substrate layer 100 using silver paste as raw material. Then, the substrate is pre-dried at 80°C for 10 min and then cured at 150°C for 60 min to obtain the silver electrode layer 101.

[0142] S3. A gasket layer 103 is prepared by printing patterned pressure-sensitive adhesive or by laser-cutting patterned PET double-sided adhesive and then aligning and attaching it between the silver electrode layer 101 and the piezoresistive layer 104.

[0143] S4. The piezoresistive layer 104 paste is printed on the surface of the top substrate layer 105 using screen printing, and then subjected to three curing processes. The three curing processes include: pre-baking at 60℃ for 20 min, holding at 100℃ for 10 min, and finally curing at 130℃ for 30 min, with a heating rate of 5℃ / min. The epoxy resin is a thermosetting epoxy resin, and the curing agent is an acid anhydride curing agent.

[0144] S5. Precisely attach the top substrate to the bottom substrate so that the piezoresistive layer 104 makes corresponding contact with the silver electrode layer 101 and the pad layer 103.

[0145] It is worth mentioning that the parameters of the screen printing method in steps S2, S3 and S4 are as follows: a 300-mesh polyester screen is used, the squeegee hardness is 70 Shore A, the squeegee pressure is 0.4 MPa, the printing speed is 40 mm / s, the screen distance is 1.5 mm, and the wet film thickness is 30 μm.

[0146] The piezoresistive layer 104 slurry can be prepared by the following method:

[0147] B1. Prepare the following raw materials: 10 parts epoxy resin, 6.5 parts curing agent, 0.15 parts accelerator, 2 parts toner, 35 parts polyurethane slurry, 15 parts solvent, and 0.2 parts toner stabilizer.

[0148] B2. Weigh the epoxy resin, curing agent and accelerator, place them in a stainless steel mixing container, start the mixing equipment, and stir at 900 r / min for 30 minutes at room temperature of 25℃ until the materials are completely dissolved and a uniform and transparent resin system is formed.

[0149] B3. Then, slowly add 60wt% toner to the resin system while stirring (keeping the stirring speed at 600 rpm). Control the addition time within 10 minutes to ensure uniform dispersion of the toner and avoid agglomeration. After the toner is evenly dispersed, add the pre-dissolved polyurethane slurry to the system, adjust the stirring speed to 1200 rpm, and continue stirring for 30 minutes to fully integrate the elastic matrix with the resin and toner. Add the remaining toner while stirring (600 rpm). Add 50wt% of 51 solvent, adjust the stirring speed to 800 rpm, and continue stirring for 1 hour to form a preliminary mixed slurry with a solid content of about 60%.

[0150] B4. Transfer all the initially mixed slurry to a stainless steel ball mill jar. Add stainless steel ball milling beads with a particle size gradient of 5mm, 3mm, and 1mm (mass ratio 2:2:1) at a slurry-to-milling-beads mass ratio of 1:3. Set the rotation speed to 5000r / min and start the equipment for ball milling for 30 minutes. The carbon powder is then dispersed secondaryly through high-energy collision. After 30 minutes of ball milling, slowly add the remaining 51 solvent to the ball mill jar and continue ball milling at 5000r / min for 10 minutes. Adjust the slurry viscosity to 40000cP (25℃). After ball milling, filter the slurry through a 200-mesh nylon screen to remove the ball milling beads and large particle impurities. Collect the filtered, uniform slurry.

[0151] B5. Transfer the filtered slurry to a vacuum homogenizer and defoamer. Set the vacuum level to -0.09MPa and the rotation speed to 1500r / min for homogenization and defoaming treatment for 10 minutes to remove air bubbles from the slurry. After homogenization and defoaming, send the slurry to a three-roll mill for fine grinding. For the first grinding, set the feed roller spacing of the three-roll mill to 70μm and the discharge roller spacing to 35μm, and control the slurry feed speed to 5L / h. Pass the slurry through the rollers twice according to these parameters to reduce the particle agglomeration size.

[0152] B6. After the three-roll milling is completed, the slurry is collected and transferred to a mixing container. The mixing speed is controlled at 800 r / min and the mixing is continued for 1 hour. After the mixing is completed, the slurry is transferred to a homogenizer and defoamer again. It is treated at 1500 r / min speed and -0.09 MPa vacuum for 10 minutes to finally obtain a uniformly dispersed, bubble-free, and viscosity-stable high-resistance carbon paste for screen printing.

[0153] The thin-film sensors prepared in Examples 1-3 were subjected to performance tests, and the test results are shown in Table 1:

[0154]

[0155]

[0156] The inventors further conducted performance tests on the thin-film sensor prepared in Example 1, and the performance test results are as follows: Figures 3-5 As shown, where Figure 3 This is a stepped pressure-step resistance characteristic curve. It shows that the sensor's resistance synchronously presents a stepped signal under different pressure levels, with a one-to-one correspondence between the two. This test demonstrates the sensor's pressure sensing capability and signal conversion performance. The clear correspondence between pressure and resistance step changes indicates that the sensor has good linear response and high sensitivity, accurately converting pressure changes into resistance changes. This shows that the sensor has high accuracy and stability in pressure measurement, reliably reflecting minute pressure changes, and is suitable for applications requiring precise pressure measurement.

[0157] Figure 4 This is a graph showing the resistance stability test under the same pressure. It illustrates the signal stability of the sensor under the same pressure, from a static resistance (>2 megohms, approximately an open circuit) to a small resistance. This test demonstrates the repeatability and stability of the sensor under a specific pressure. If the signal remains stable as the resistance changes from a static state to a small resistance under the same pressure, it indicates that the sensor has good repeatability and anti-interference capabilities. This shows that the sensor can provide stable measurement results in practical applications, maintaining high accuracy and reliability even under environmental changes or long-term operation, making it suitable for scenarios requiring long-term stable monitoring.

[0158] Figure 5 This is a wrist pulse signal detection graph (cun, guan, and chi signals). It shows that the sensor is attached to the wrist and simultaneously detects the cun, guan, and chi pulse signals, with each signal's characteristic peaks being clear and distinct.

[0159] This test demonstrates the sensor's performance in the biomedical field. It shows that the sensor possesses high sensitivity and good spatial resolution, accurately distinguishing and clearly capturing pulse signals at different locations on the wrist (cun, guan, chi). This indicates the sensor's excellent performance in monitoring human physiological signals, providing technical support for the modernization and objectification of traditional Chinese medicine pulse diagnosis. It is also suitable for other medical scenarios requiring precise monitoring of human pulse signals, providing accurate and reliable pulse data for medical diagnosis, and contributing to the early detection and treatment of diseases.

[0160] While the disclosure is as stated above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of this disclosure, and all such changes and modifications will fall within the protection scope of this invention.

Claims

1. A thin-film pressure sensor for monitoring the three pulses (cun, guan, chi) in traditional Chinese medicine pulse diagnosis, characterized in that, include: Underlying substrate layer; A silver electrode layer is patterned on the underlying substrate layer, and the silver electrode layer includes three electrode regions corresponding to the positions of cun, guan, and chi. A pad layer is patterned on the silver electrode layer; A piezoresistive layer is disposed on the pad layer and makes corresponding contact with the three electrode regions of the silver electrode layer; A top substrate layer is disposed on the piezoresistive layer; The piezoresistive layer changes resistance under pressure, and outputs an electrical signal through the silver electrode layer, thereby monitoring the pulse pressure at the cun, guan, and chi positions.

2. A method for fabricating a thin-film pressure sensor as described in claim 1, characterized in that, The preparation method specifically includes the following steps: S1. Flexible substrate is used as the raw material for the bottom substrate layer and the top substrate layer, and is prepared for use after cleaning. S2. Using screen printing, silver electrode patterns are printed on the surface of the cleaned substrate layer using silver paste as raw material, and then a curing process is performed to obtain the silver electrode layer. S3. A gasket layer is prepared by printing patterned pressure-sensitive adhesive or by laser-cutting patterned PET double-sided adhesive and then aligning and attaching it between the silver electrode layer and the piezoresistive layer. S4. The pressure resistance layer paste is printed on the surface of the top substrate layer using screen printing, and then three curing processes are performed. S5. The top substrate layer with the piezoresistive layer printed on it is attached to the gasket layer and the silver electrode layer of the bottom substrate, so that the piezoresistive layer is in corresponding contact with the silver electrode layer and the gasket layer.

3. The preparation method according to claim 2, characterized in that, The raw material for the flexible substrate is selected from PET, PI, TPU and printable fabrics.

4. The preparation method according to claim 2, characterized in that, The pressure resistance layer slurry is composed of the following components: 10-30 parts epoxy resin, 6.5-19.5 parts curing agent, 0.15-0.45 parts accelerator, 4-14 parts toner, 35-55 parts polyurethane slurry, 15-25 parts solvent, and 0.2-1 parts dispersant. The carbon powder is composed of beaded carbon black, sheet graphene powder and carbon nanotubes in a mass ratio of 2:1:

2. The median particle size of the beaded carbon black is 25 nm, the median particle size of the sheet graphene powder is 5 μm, and the average diameter of the carbon nanotubes is 7-12 nm and the length is 50-250 μm.

5. The preparation method according to claim 4, characterized in that, The piezoresistive layer slurry is prepared by the following method: A1. Raw material pretreatment and mixing: Weigh the epoxy resin, curing agent and accelerator according to the formula, stir evenly to obtain the resin system, then slowly add 3 / 5 of the total amount of carbon powder, stir evenly, add polyurethane slurry, stir evenly, then add the remaining 2 / 5 of the carbon powder and 1 / 2 of the total amount of solvent, stir evenly to form a preliminary mixed slurry. A2. Ball milling dispersion: The initially mixed slurry is ball milled with stainless steel ball milling beads, and then the remaining 1 / 2 of the solvent is added and the ball milling process is continued to adjust the slurry viscosity to 40000 cP. A3. Filtration and Homogenization / Defoaming: After filtering the slurry, homogenization and defoaming treatment are performed. A4. Three-roll milling: The slurry is fed into a three-roll mill for grinding. A5. Mixing treatment: The slurry after grinding is mixed again; A6. Second homogenization and defoaming: The pressure resistance layer slurry is obtained by homogenizing and defoaming again.

6. The preparation method according to claim 2, characterized in that, In step S1, the cleaning process includes wiping the substrate surface with anhydrous ethanol and drying it at 100-130°C for 30 minutes.

7. The preparation method according to claim 2, characterized in that, In steps S2, S3 and S4, the parameters of the screen printing method are as follows: a 100-350 mesh polyester screen is used, the squeegee hardness is 70 Shore A, the squeegee pressure is 0.3-0.4 MPa, the printing speed is 30-40 mm / s, the screen distance is 1.5 mm, and the wet film thickness is 20-30 μm.

8. The preparation method according to claim 2, characterized in that, The first curing process in step S2 includes: pre-drying at 60-80℃ for 10 min, and then curing at 120-150℃ for 30-60 min.

9. The preparation method according to claim 2, characterized in that, The secondary curing process described in step S3 is carried out at 100-120℃ for 40-50 minutes.

10. The preparation method according to claim 2, characterized in that, The three curing processes in step S4 include: first, pre-baking at 50-60℃ for 10-20 minutes, then holding at 80-100℃ for 10 minutes, and finally curing at 100-130℃ for 30 minutes, wherein the heating rate is 4-5℃ / min.

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