Intelligent insole based on human foot state recognition and preparation method thereof

Abstract

The invention discloses an intelligent insole based on human body foot state recognition and a preparation method thereof. The intelligent insole is internally provided with at least one pressure sensor, a biocompatible layer and a piezoresistive sensitive layer, wherein the biocompatible layer and the piezoresistive sensitive layer are compounded with each other; the pressure sensor is connected with the microprocessor through data transmission; the pressure sensor is arranged in the insole and connected with the PCB, and the PCB is connected with a power source. The intelligent insole capable of recognizing the human foot state is simple in processing technology, low in price, good in biocompatibility, capable of monitoring personal plantar pressure distribution in real time, capable of avoiding plantar wound infection of a patient during use and great in application potential in the field of medical detection.

Description

Technical Field

[0001] The invention relates to an intelligent insole for identifying the state of a human foot and a preparation method thereof, and belongs to the technical field of force perception and textile wearable measurement. Background Art

[0002] Diabetic foot ulcer (DFU) is one of the important complications of diabetes, and about 60% of diabetic foot ulcers come from neuropathy. These ulcers may lead to serious health problems, including the risk of amputation. Therefore, early detection and subsequent recovery of foot ulcers are crucial for diabetic patients. This can be achieved by monitoring the patient's foot pressure and shear force.

[0003] In recent years, artificial intelligence-based technologies have been developed to improve remote monitoring of diabetic foot ulcers through the use of mobile applications. The application of these technologies will help to detect and treat foot ulcers at an early stage and reduce related complications. Studies have shown that the continuous plantar pressure monitoring and dynamic decompression guidance provided by the smart insole system can reduce the recurrence of diabetic foot ulcers. The smart insole system can achieve remote monitoring, relieve patients' pain in a timely manner, and avoid foot deformities and deep damage caused by abnormal pressure distribution.

[0004] At present, the commonly used flexible foot pressure sensors in the market are mainly from foreign countries, such as the foot pressure detection system of Tekscan Company in the United States. This system has a high pressure measurement level, but it is expensive and not suitable for daily home use. Moreover, most foot pressure sensors do not take into account the user experience of users with foot diseases. If there are many bacteria on the surface of the sensor, it may even cause the patient's foot condition to worsen, affecting the patient's use. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide an intelligent insole for identifying the state of human feet, so that users can comfortably monitor their personal plantar pressure distribution in real time at home, which helps to discover foot problems in the early stages and can also provide doctors with clearer and more accurate patient plantar pressure distribution maps, making it easier for doctors to customize more reasonable treatment plans for patients.

[0006] In order to solve the above problems, the present invention provides a method for preparing a smart insole based on human foot state recognition, wherein the smart insole is provided with at least one pressure sensor, a biocompatible layer and a piezoresistive sensitive layer composited with each other by the pressure sensor;

[0007] The method for preparing the biocompatible layer comprises the following steps:

[0008] Step 1): chitosan and sodium alginate are respectively placed in a NaCl solution and mixed and stirred to dissolve to obtain a chitosan solution and a sodium alginate solution, and the pH values ​​of the two solutions are adjusted to 5;

[0009] Step 2): soaking the PET film in a propanol solution of 1,6-hexanediamine for 4 to 5 hours and drying; soaking the dried PET film alternately in a chitosan solution and a sodium alginate solution, and finally washing with deionized water and drying to obtain a biocompatible layer;

[0010] The method for preparing the piezoresistive sensitive layer comprises the following steps:

[0011] Step a): diluting carbon black ink to obtain a carbon black solution, adding graphene to the carbon black solution, mixing and stirring, and drying and evaporating excess solvent to obtain a mixture of graphene and carbon black ink;

[0012] Step b): mixing dipropylene glycol methyl ether, 2-(2-ethoxyethoxy) ethyl acetate, a mixture of graphene and carbon black ink, and fatty acid methyl ester sulfonate to form a mixed solution;

[0013] Step c): mixing dipropylene glycol methyl ether and phenoxy resin and stirring until the phenoxy resin is gradually dissolved, and then mixing and dispersing the mixed solution obtained in step b) to obtain a piezoresistive sensitive solution;

[0014] Step d): using wool fabric as a substrate, coating the piezoresistive sensitive solution by screen printing to obtain a piezoresistive sensitive layer;

[0015] The biocompatible layer is compounded with the piezoresistive sensitive layer to obtain a pressure sensor;

[0016] The pressure sensor is connected to the microprocessor through data transmission; the pressure sensor is placed in the insole, the pressure sensor is connected to the PCB board, and the PCB board is connected to a power supply.

[0017] Preferably, in step 1), the pH adjuster used for adjusting the pH value is acetic acid or alkaline solution.

[0018] Preferably, in the step 2), the PET film is cleaned with acetone, ethanol and deionized water respectively before use, and then placed in a drying oven for drying; the PET film is immersed in the chitosan solution and the sodium alginate solution for 30 times respectively.

[0019] Preferably, in the step b), the mass ratio of dipropylene glycol methyl ether, 2-(2-ethoxyethoxy) ethyl acetate, a mixture of graphene and carbon black ink, and fatty acid methyl ester sulfonate is 6:2:1:0.1.

[0020] Preferably, in step c), the mass ratio of dipropylene glycol methyl ether to phenoxy resin is 8:2.

[0021] Preferably, the data transmission is Bluetooth, 2.4G wireless technology or Wi-Fi technology, preferably Bluetooth technology is used as the main data transmission means to achieve effective data exchange and control.

[0022] Preferably, the number of the pressure sensors is 3, which are respectively arranged at the first iliac fossa, the fourth iliac fossa and the heel position of the insole, which can not only save energy consumption and extend the single use time, but also capture the key pressure distribution data of the foot.

[0023] Preferably, the power supply and PCB board are placed at the tongue of the shoe, which can avoid direct contact with the wearer and facilitate the connection between the sensor and other circuit components.

[0024] Preferably, the microprocessor adopts a gait recognition algorithm, including at least one of SVM, KNN, and XGBoost.

[0025] The present invention also provides an intelligent insole based on human foot state recognition prepared by the above preparation method.

[0026] The present invention proposes a design and preparation method of an intelligent insole for identifying the state of human feet. The intelligent insole for identifying the state of human feet has a simple processing technology, is inexpensive, has good biocompatibility, can monitor an individual's plantar pressure distribution in real time, and is a biocompatible flexible plantar pressure sensor that can prevent plantar wound infection in patients and display plantar pressure distribution. It has great application potential in the field of medical testing.

[0027] The intelligent insole for human foot status recognition in the present invention adopts piezoresistive sensing, which forms a graphene-carbon black-graphene conductive structure by mixing a carbon black solution and a small amount of graphene. The foot contact pressure sensor has a biocompatible layer on the side that directly contacts the foot and a piezoresistive sensitive layer on the other side. The core principle of the sensor is the piezoresistive effect. It is powered by an external power source such as a lithium battery, and uses the pressure sensor as the source of data acquisition. The plantar pressure signal is collected through the hardware circuit, and the microprocessor processes the signal and transmits the data to the host computer through the Bluetooth module.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The design and preparation of the biocompatible layer of the smart insole for human foot status recognition is less likely to breed bacteria than the surface of general sensors and is harmless to the human body. In practical applications, it can effectively reduce the risk of worsening wound infection in users with foot diseases.

[0030] (2) The design and preparation of the piezoresistive sensitive layer of the intelligent insole for human foot status recognition uses a mixed solution of carbon black and graphene as the conductive material to form a conductive structure of graphene-carbon black-graphene, and the system is stable.

[0031] (3) Design and preparation of the piezoresistive sensitive layer of the intelligent insole for human foot status recognition. The piezoresistive sensitive layer is treated with phenoxy resin, which can serve as an adhesive to increase the adhesion of the conductive solution and wool fabric. At the same time, after it is mixed with graphene carbon black, it produces a porous structure at the microscopic level, which significantly increases the sensitivity of the pressure-sensitive material.

[0032] (4) The present invention innovatively designs a smart insole for human foot status recognition, which mainly includes three core parts: pressure sensor, hardware design and host computer program. The preparation of the pressure sensor mainly includes the preparation of the biocompatible layer and the piezoresistive sensitive layer. The prepared smart insole has a simple processing technology, low price, good biocompatibility, can monitor the individual's plantar pressure distribution in real time, and avoid the patient's plantar wound infection when used. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A schematic diagram of the distribution of pressure sensors on the smart insole provided by the present invention;

[0034] Figure 2 A schematic diagram of the positions of the PCB board and the power supply on the smart insole provided by the present invention;

[0035] Figure 3 A data signal diagram of a pressure sensor 1 of the smart insole provided by the present invention;

[0036] Figure 4 A data signal diagram of the pressure sensor 2 of the smart insole provided by the present invention;

[0037] Figure 5 This is a data signal diagram of the pressure sensor 3 of the smart insole provided by the present invention. DETAILED DESCRIPTION

[0038] In order to make the present invention more clearly understood, preferred embodiments are described in detail below with reference to the accompanying drawings.

[0039] Example 1

[0040] Preparation of biocompatible layer:

[0041] (1) The PET film was cleaned with acetone, ethanol and deionized water for 15 to 20 minutes respectively, and then placed in a drying oven for drying;

[0042] (2) preparing a 0.06 g / mL 1,6-hexanediamine / propanol solution, stirring continuously for 5 hours to ensure that it is fully dissolved, and soaking the dried PET film in the prepared 1,6-hexanediamine / propanol solution for 4 to 5 hours, and then drying it in a drying oven;

[0043] (3) preparing a 0.01 mol / L NaCl solution containing 0.2 wt % acetic acid, dissolving chitosan in the prepared NaCl solution to make the chitosan concentration 1 mg / mL, and obtaining a chitosan solution; preparing a 0.01 mol / L NaCl solution, dissolving sodium alginate in the prepared NaCl solution to make the sodium alginate concentration 1 mg / mL, and obtaining a sodium alginate solution; and adjusting the pH value of the two solutions to 5 using acetic acid and alkali solution;

[0044] (4) The dried PET film was alternately immersed in a chitosan solution and a sodium alginate solution for 30 times, each time for 3 minutes, and finally washed with deionized water and dried to obtain a biocompatible layer.

[0045] Preparation of piezoresistive sensitive layer:

[0046] (1) appropriately diluting the carbon black ink to obtain a carbon black solution of a certain viscosity, wherein the mass ratio of the carbon black ink to the diluent is about 1:2; adding graphene to the carbon black solution, wherein the mass ratio of the carbon black to the graphene is about 19:1, mixing and stirring, and drying and evaporating other excess solvents to obtain graphene / carbon black ink;

[0047] (2) mixing dipropylene glycol methyl ether, 2-(2-ethoxyethoxy) ethyl acetate, graphene / carbon black ink, and fatty acid methyl ester sulfonate in a mass ratio of 6:2:1:0.1 and stirring for 1 hour;

[0048] (3) mixing dipropylene glycol methyl ether and phenoxy resin in a mass ratio of 8:2 and stirring until the phenoxy resin is gradually dissolved in the solvent to form a substance with a certain viscosity;

[0049] (4) mixing the substances obtained in (2) and (3), and rapidly stirring the mixed solution to disperse it, thereby obtaining a piezoresistive sensitive solution;

[0050] (5) Using wool fabric as a substrate, a piezoresistive sensitive solution is coated by screen printing to obtain a piezoresistive sensitive layer.

[0051] The biocompatible layer and the piezoresistive sensitive layer are combined to obtain a pressure sensor. The pressure sensor is cut into a desired shape (circular in this embodiment) and placed in the insole. Figure 1 As shown, pressure sensor three 3 is arranged at the first rib of the insole, pressure sensor one 1 is arranged at the fourth rib of the insole, and pressure sensor two 2 is arranged at the heel position of the insole.

[0052] The three pressure sensors are connected to a PCB board 4, and the PCB board 4 is connected to a power supply 5. The power supply 5 and the PCB board 4 are placed at the tongue position of the shoe.

[0053] The pressure sensor is connected to the microprocessor via Bluetooth. The microprocessor adopts gait recognition algorithms, including KNN and XGBoost.

[0054] Using the above-mentioned smart insole, the foot pressure signals of the three pressure sensors in the insole are plotted when walking on flat ground. Figure 3-5 Reflects the changes in foot pressure when walking on flat ground.

Claims

1. A method for preparing a smart insole based on human foot state recognition, characterized in that: The smart insole is provided with at least one pressure sensor, and the pressure sensor comprises a biocompatible layer and a piezoresistive sensitive layer composited with each other; The method for preparing the biocompatible layer comprises the following steps: Step 1): chitosan and sodium alginate are respectively placed in a NaCl solution and mixed and stirred to dissolve to obtain a chitosan solution and a sodium alginate solution, and the pH values ​​of the two solutions are adjusted to 5; Step 2): soaking the PET film in a propanol solution of 1,6-hexanediamine for 4 to 5 hours and drying; soaking the dried PET film alternately in a chitosan solution and a sodium alginate solution, and finally washing with deionized water and drying to obtain a biocompatible layer; The method for preparing the piezoresistive sensitive layer comprises the following steps: Step a): diluting carbon black ink to obtain a carbon black solution, adding graphene to the carbon black solution, mixing and stirring, and drying and evaporating excess solvent to obtain a mixture of graphene and carbon black ink; Step b): mixing dipropylene glycol methyl ether, 2-(2-ethoxyethoxy) ethyl acetate, a mixture of graphene and carbon black ink, and fatty acid methyl ester sulfonate to form a mixed solution; Step c): mixing dipropylene glycol methyl ether and phenoxy resin and stirring until the phenoxy resin is gradually dissolved, and then mixing and dispersing the mixed solution obtained in step b) to obtain a piezoresistive sensitive solution; Step d): using wool fabric as a substrate, coating the piezoresistive sensitive solution by screen printing to obtain a piezoresistive sensitive layer; The biocompatible layer is compounded with the piezoresistive sensitive layer to obtain a pressure sensor; The pressure sensor is connected to the microprocessor through data transmission; the pressure sensor is placed in the insole, the pressure sensor is connected to the PCB board, and the PCB board is connected to a power supply.

2. The method for preparing the intelligent insole based on human foot state recognition according to claim 1, characterized in that: In the step 1), the pH value is adjusted by acetic acid or alkali solution.

3. The method for preparing the intelligent insole based on human foot state recognition according to claim 1, characterized in that: In the step 2), the PET film is cleaned with acetone, ethanol and deionized water respectively before use, and then placed in a drying oven for drying; the PET film is immersed in the chitosan solution and the sodium alginate solution for 30 times respectively.

4. The method for preparing the intelligent insole based on human foot state recognition according to claim 1, characterized in that: In the step b), the mass ratio of dipropylene glycol methyl ether, 2-(2-ethoxyethoxy) ethyl acetate, a mixture of graphene and carbon black ink, and fatty acid methyl ester sulfonate is 6:2:1:0.

1.

5. The method for preparing the intelligent insole based on human foot state recognition according to claim 1, characterized in that: In the step c), the mass ratio of dipropylene glycol methyl ether to phenoxy resin is 8:

2.

6. The method for preparing the intelligent insole based on human foot state recognition according to claim 1, characterized in that: The data transmission is Bluetooth, 2.4G wireless technology or Wi-Fi technology.

7. The method for preparing the intelligent insole based on human foot state recognition according to claim 1, characterized in that: The number of the pressure sensors is 3, which are respectively arranged at the first trochanter bone, the fourth trochanter bone and the heel position of the insole.

8. The method for preparing the intelligent insole based on human foot state recognition according to claim 1, characterized in that: The power supply and the PCB board are placed at the tongue of the shoe.

9. The method for preparing the intelligent insole based on human foot state recognition according to claim 1, characterized in that: The microprocessor adopts a gait recognition algorithm, including at least one of SVM, KNN, and XGBoost.

10. A smart insole based on human foot state recognition prepared by the preparation method according to any one of claims 1 to 9.

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