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CN-115024698-B - Flexible pressure sensor for monitoring pulse wave and preparation method thereof

CN115024698BCN 115024698 BCN115024698 BCN 115024698BCN-115024698-B

Abstract

The invention relates to a flexible pressure sensor for monitoring pulse waves and a preparation method thereof, wherein a sensitive layer and an interdigital electrode are respectively prepared first and then assembled to obtain the flexible pressure sensor for monitoring pulse waves, the prepared flexible pressure sensor for monitoring pulse waves comprises the sensitive layer and the interdigital electrode, the two electrodes of the interdigital electrode are connected through a wire, the sensitive layer is a polymer elastomer film with a rigid convex microstructure array on the surface, the rigid convex microstructure array is a convex microstructure array based on conductive metal, the highest sensitivity of the flexible pressure sensor is not lower than 9.5kPa ‑1 , the response time is not higher than 30ms, and the mechanical detection lower limit is not higher than 8Pa. The rigid bulge microstructure constructed on the surface of the flexible sensitive layer has no lag and no damping on the response of mechanical stimulus, can endow the pressure sensor with high sensitivity, high response speed and low detection lower limit performance, and has the advantages of simple preparation method and low production cost, thereby being suitable for large-scale industrial production.

Inventors

  • CUI XIHUA
  • XU ZHIGUANG

Assignees

  • 嘉兴学院

Dates

Publication Date
20260508
Application Date
20220512

Claims (8)

  1. 1. The flexible pressure sensor for monitoring pulse waves comprises a sensitive layer and interdigital electrodes, wherein the two electrodes of the interdigital electrodes are connected through a wire; The rigid bulge microstructure array is a bulge microstructure array based on conductive metal, wherein the conductive metal is gold, silver or copper, the shape of bulges in the rigid bulge microstructure array is hemispherical, the diameter of each hemisphere is 0.1-1.0 mm, and the center of sphere of two adjacent hemispherical bulges is 0.15-1.5 mm; The highest sensitivity of the flexible pressure sensor is not lower than 9.5kPa -1 , the response time is not higher than 30ms, and the mechanical detection lower limit is not higher than 8Pa.
  2. 2. The flexible pressure sensor for monitoring pulse waves of claim 1, wherein the thickness of the polymer elastomer film is 0.2-0.5 mm; The metal thickness of the interdigital electrode is 100-200 nm, the length of the interdigital electrode is 10-20 mm, the width of the interdigital electrode is 10-20 mm, and the finger width and the finger spacing of the interdigital electrode are 0.2-2.0 mm.
  3. 3. The method for preparing the flexible pressure sensor for monitoring pulse waves according to any one of claims 1-2, which is characterized in that the sensitive layer and the interdigital electrode are prepared respectively first, and then the flexible pressure sensor for monitoring pulse waves is assembled; The rigid convex microstructure array on the surface of the sensitive layer is prepared by an additive manufacturing technology.
  4. 4. A method according to claim 3, characterized in that the specific preparation steps are as follows: (1) Uniformly coating a layer of polymer elastomer precursor liquid or elastic polymer solution on a plane mould, placing the mould in an oven for complete solidification, and uncovering the film to obtain a polymer elastomer film; (2) Constructing a raised microstructure array based on conductive metal slurry on the surface of a polymer elastomer film by an additive manufacturing technology, and forming a rigid raised microstructure array based on conductive metal after heating and curing to prepare the sensitive layer; (3) Firstly, sequentially ultrasonically cleaning a polymer film in acetone, ethanol and deionized water, drying, then performing plasma treatment on the surface of the polymer film, then covering a mask plate with an interdigital structure on the polymer film, then depositing a metal conductive material on the polymer film, and finally removing the mask plate to obtain the interdigital electrode; (4) And (3) contacting one side of the sensitive layer surface prepared in the step (2) with the rigid convex microstructure array with the electrode surface of the interdigital electrode prepared in the step (3), and packaging by using an adhesive to prepare the flexible pressure sensor for monitoring pulse waves.
  5. 5. The method of claim 4, wherein the polymer elastomer precursor liquid in step (1) is a polydimethylsiloxane precursor liquid and the elastomeric polymer solution is a thermoplastic polyurethane solution or a hydrogenated styrene-butadiene block copolymer solution; when the polymer elastomer precursor liquid is coated, the curing temperature is 70-120 ℃ and the curing time is 60-180 minutes; when the elastic polymer solution is coated, the curing temperature is 50-80 ℃ and the curing time is 12-24 hours.
  6. 6. The method of claim 4, wherein the additive manufacturing technique in step (2) is a pneumatic direct write technique, an ammeter jet printing technique, or an electrospinning technique; The curing temperature in the step (2) is 70-100 ℃ and the curing time is 60-120 minutes.
  7. 7. The method of claim 4, wherein the polymer film in step (3) is polyimide, polyethylene terephthalate, or polydimethylsiloxane; The ultrasonic cleaning time is 0.1-0.5 h; The plasma treatment time is 10-30 minutes; The metal conductive material is more than one of gold, silver and copper; The deposition mode of the metal conductive material is one or more of vacuum evaporation, magnetron sputtering and screen printing.
  8. 8. The method of claim 4, wherein the adhesive in step (4) is one or more of a polydimethylsiloxane precursor solution, a polyimide insulating tape, and a polyurethane medical tape; The two electrodes of the interdigital electrode are connected through a wire and fixed by using conductive adhesive; the conducting wire is copper wire or copper foil, and the conducting adhesive is conducting silver paste or conducting carbon paste.

Description

Flexible pressure sensor for monitoring pulse wave and preparation method thereof Technical Field The invention belongs to the technical field of pressure sensors, and relates to a flexible pressure sensor for monitoring pulse waves and a preparation method thereof. Background The pulse wave of human body contains a large number of physiological signals, can continuously reflect the regular change trend of hemodynamic parameters such as heart rate, blood oxygen, blood pressure and the like of the human body, and is used for evaluating the cardiovascular performance. In the traditional Chinese medicine field, pulse diagnosis is also one of important diagnosis modes, but pulse diagnosis mainly depends on experience of traditional Chinese medicine to carry out subjective judgment, so that diagnosis results have great difference and are difficult to objectively quantify. The appearance of pulse-taking instrument provides conditions for the objective standardized diagnosis of traditional Chinese medicine, but the traditional pulse-taking instrument has larger volume and cannot be used for real-time wearable monitoring and wide popularization and application. The flexible pressure sensor is used for collecting and analyzing pulse wave signals of a human body, converting the pulse wave signals into digital signals for quantitative analysis, and the flexible pressure sensor has important application prospects in the field of wearable and continuous monitoring of cardiovascular diseases. In order to realize high-quality monitoring of weak signals of pulse waves, a convex microstructure is usually introduced into a flexible pressure sensor to improve the sensitivity of the sensor, but the traditional flexible sensor is composed of flexible polymer elastomer from a matrix to the microstructure, and the flexible polymer material has high viscoelasticity, high damping and hysteresis for mechanical stimulation, so that the mechanical detection lower limit of the flexible pressure sensor is high, the response speed is low, and high-resolution and high-quality monitoring of characteristic peaks contained in pulse wave signals cannot be realized. Therefore, the research of the flexible pressure sensor which can monitor the pulse wave signals and has high sensitivity and quick response and the preparation method thereof has very important significance. Disclosure of Invention The invention aims to solve the problems in the prior art and provides a flexible pressure sensor for monitoring pulse waves and a preparation method thereof. In order to achieve the above purpose, the invention adopts the following technical scheme: The flexible pressure sensor for monitoring pulse waves comprises a sensitive layer and interdigital electrodes, wherein the two electrodes of the interdigital electrodes are connected through a wire, and the sensitive layer is a polymer elastomer film with a rigid convex microstructure array on the surface; the rigid convex microstructure array is a convex microstructure array based on conductive metal; The highest sensitivity of the flexible pressure sensor is not lower than 9.5kPa -1, the response time is not higher than 30ms, and the mechanical detection lower limit is not higher than 8Pa. As a preferable technical scheme: a flexible pressure sensor for monitoring pulse waves as described above, wherein the conductive metal is gold, silver or copper. The flexible pressure sensor for monitoring pulse waves is characterized in that the thickness of the polymer elastomer film is 0.2-0.5 mm; The metal thickness of the interdigital electrode is 100-200 nm, the length of the interdigital electrode is 10-20 mm, the width of the interdigital electrode is 10-20 mm, and the finger width and the finger spacing of the interdigital electrode are 0.2-2.0 mm. According to the flexible pressure sensor for monitoring pulse waves, the shape of the protrusions in the rigid protrusion microstructure array is hemispherical, the diameter of each hemisphere is 0.1-1.0 mm (less than 0.1mm, which is difficult to realize by the existing additive manufacturing technology, and the size of the protrusion microstructure is too large to play a role in sensitization when the diameter of the protrusion microstructure is higher than 1.0 mm), and the center-to-center distance between every two adjacent hemispherical protrusions is 0.15-1.5 mm. The invention also provides a flexible pressure sensor for monitoring pulse waves, which is prepared by respectively preparing the sensitive layer and the interdigital electrode and then assembling the sensitive layer and the interdigital electrode; The rigid bulge microstructure array on the surface of the sensitive layer is prepared by an additive manufacturing technology, and is limited by a preparation method of a microstructure, wherein the microstructure in the prior art is mainly prepared indirectly by a template method, only flexible polymer materials can be used for forming the microstruct