Porous force-sensitive material, flexible pressure sensor and especially made wearable smart insole for high altitude environment

Abstract

The application discloses a porous force-sensitive material, a flexible pressure sensor and a wearable smart insole for a plateau environment, in particular, is manufactured, and belongs to the field of sensor preparation.The porous force-sensitive material is prepared from raw materials with the following mass percentages: 5-15% of sodium phosphate, 35-55% of polyvinyl alcohol, 15-25% of glycerol and 5-10% of nano-bismuth telluride; and the method of "water medium dissolution + stirring dispersion + baking solidification" is adopted for preparation.The application solves the problems of poor measurement sensitivity of a traditional smart insole pressure sensor, a small measurement range, and easy damage and failure in a low-temperature plateau environment.

Description

Technical Field

[0001] This invention relates to the field of smart sensors, and more particularly to porous force-sensitive materials, flexible pressure sensors, and wearable smart insoles made therefrom for use in high-altitude environments. Background Technology

[0002] The extreme conditions of high-altitude training, such as low air pressure, low oxygen, and extreme cold, pose significant challenges to the management of training processes for officers and athletes. The low-oxygen, high-altitude environment easily leads to training injuries, causing considerable harm to the physical and mental health of officers and athletes. Therefore, intelligent monitoring of the high-altitude training process is crucial. Smart insoles can monitor gait information in real time during training, and are easily integrated into wearable devices without creating additional burdens, making them an important tool for intelligent monitoring.

[0003] However, existing smart insoles face problems such as easy damage in cold environments, reduced device sensitivity, narrowed device range, and even device failure, making them unable to achieve effective monitoring in actual high-altitude training. Summary of the Invention

[0004] One of the objectives of this invention is to provide a porous force-sensitive material to solve the above-mentioned problems.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A porous force-sensitive material, said porous force-sensitive material being made from the following raw materials in the following mass percentages:

[0007] Ionic electrolyte 5%–15%, polyvinyl alcohol 35%–65%, polyol 5%–35%, nano-bismuth telluride 5%–10%;

[0008] A porous force-sensitive material composed of an alcohol matrix, random pores, and bismuth telluride nanoparticles was prepared using the above-mentioned raw materials.

[0009] As a preferred technical solution, the ionic electrolyte is sodium phosphate and the polyol is glycerol.

[0010] Glycerol can be replaced by other polyols.

[0011] Ionic electrolytes are electrolytes composed of ions, specifically cations and anions, capable of conducting electric current in solution or molten state. These electrolytes dissociate into their constituent ions upon dissolution or melting, thus forming a medium for the movement of charged particles.

[0012] Examples of ionic electrolytes:

[0013] Salt water (NaCl solution): When dissolved in water, sodium chloride (NaCl) dissociates into sodium cations (Na+).+ ) and chloride anion (Cl - This forms an ionic electrolyte solution capable of conducting electric current.

[0014] Sulfuric acid (H2SO4): Sulfuric acid dissociates into hydrogen cations (H+). + ) and sulfate anions (SO4) 2- This allows it to function as an ionic electrolyte in various applications.

[0015] Potassium hydroxide (KOH) solution: Potassium hydroxide dissociates into potassium cations (K+). + ) and hydroxide anions (OH-) - This makes it an ionic electrolyte solution for use in alkaline batteries and other electrochemical systems.

[0016] Lithium-ion battery electrolytes: Lithium-ion batteries use various ionic electrolytes, such as lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), or lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), which promote the reaction of lithium cations (Li...) during charging and discharging. + () moves between the battery electrodes.

[0017] The second objective of this invention is to provide a method for preparing the above-mentioned porous force-sensitive material, comprising the following steps:

[0018] (1) First, water is used as the dissolving and dispersing medium to dissolve sodium phosphate and polyvinyl alcohol;

[0019] (2) Then, it is mixed with glycerol to form an aqueous ionic gel solution;

[0020] (3) Subsequently, the aqueous ionic gel solution and nano-bismuth telluride particles are mechanically stirred and dispersed.

[0021] (4) Then, mechanical stirring forms a foam fluid and it is coated into a thin layer.

[0022] (5) Finally, during the curing and film formation stage, the alcoholic ionic gel porous foam film is retained by using the baking evaporation medium water.

[0023] To obtain highly uniformly dispersed ionic gels, this invention innovatively proposes a two-step method of "aqueous medium dissolution + stirring dispersion". In the aqueous medium dissolution method, water is used as the dissolution and dispersion medium to dissolve sodium phosphate and polyvinyl alcohol, which are then mixed with glycerol to form an aqueous ionic gel solution. During the curing and film-forming stage, the medium water is evaporated by baking, and finally the alcoholic ionic gel is retained.

[0024] Stirring dispersion refers to the mechanical stirring and dispersion of the mixed aqueous ionic gel solution and bismuth telluride nanoparticles.

[0025] Furthermore, in order to obtain a porous foam structure, the speed of mechanical stirring, the baking and curing temperature, and the curing speed are controlled so that the air bubbles formed by mechanical stirring do not have time to dissipate and are thus cured to form a porous foam.

[0026] As a preferred technical solution, in step (4), the mechanical stirring is 1500 rpm to 3000 rpm.

[0027] Regarding rotational speed: speeds below 1500 rpm result in larger pore sizes in the foam formed by mechanical stirring, making it easier for the foam to dissipate during heating. Higher rotational speeds produce better foam quality; however, due to the speed limitations of the mechanical stirring motor, it is difficult to achieve higher speeds.

[0028] As a preferred technical solution, in step (5), the baking temperature is 60-80℃ and the baking time is 1-5 h.

[0029] Baking temperature: Generally between 60 and 80°C, because sufficient temperature is needed to dry the foam (avoiding slow curing and foam collapse due to excessively low temperature). However, excessively high temperature will damage the structure of the organic matrix in the foam or denature the ionic electrolyte. Therefore, it is generally between 60 and 80°C.

[0030] Baking time: Baking time is usually 1 to 5 hours, to dry the moisture in the gel. Therefore, the baking time is related to the water content in the prepared gel fluid.

[0031] The third objective of this invention is to provide a flexible pressure sensor, wherein the flexible pressure sensor uses conductive fabric as the upper and lower electrodes and the aforementioned porous force-sensitive material as the intermediate force-sensitive layer.

[0032] The fourth objective of this invention is to provide a wearable smart insole for use in high-altitude environments: the insole includes at least two of the aforementioned flexible pressure sensors, and also includes a signal processing module, a wireless transmission module, and a power supply module electrically connected to the flexible pressure sensors, preferably a rechargeable battery.

[0033] As a preferred technical solution, the number of pressure sensors in a single insole is 5 to 50.

[0034] The force-sensitive material of this invention is composed of low-temperature resistant ion gel and bismuth telluride nanoparticles. In order to improve the sensitivity and range of the device under low-temperature conditions, a porous foam structure was further designed to construct a flexible pressure sensor based on the porous foam force-sensitive material. Finally, a low-temperature resistant smart insole was prepared based on the multi-point pressure sensor.

[0035] Compared with the prior art, the advantages of the present invention are: the present invention solves the problems of poor measurement sensitivity, small measurement range, and easy damage and failure in low temperature and high altitude environments of traditional smart insole pressure sensors. Specifically, the traditional smart insole has a maximum pressure of ~1 MPa and a low temperature of ~-10°C; while the smart insole of the present invention (suitable for scenarios with great impact force on the sole of the foot, such as long jump and high jump) has a maximum pressure of ~5 MPa and a low temperature of ~-30°C. Attached Figure Description

[0036] Figure 1 This is a flowchart illustrating the fabrication process of the force-sensitive material according to Embodiment 1 of the present invention.

[0037] Figure 2 This is a three-dimensional structural diagram of the force-sensitive material obtained in Example 1 of the present invention;

[0038] Figure 3 This is a three-dimensional structural diagram of the flexible pressure sensor according to Embodiment 1 of the present invention;

[0039] Figure 4 This is a three-dimensional structural diagram of the smart insole according to Embodiment 1 of the present invention.

[0040] In the figure: 1. Alcohol-based matrix; 2. Random pores; 3. Bismuth telluride nanoparticles; 4. Upper electrode; 5. Lower electrode; 6. Intermediate force-sensitive layer; 7. Flexible pressure sensor; 8. Substrate; 9. Signal processing module; 10. Wireless transmission module; 11. Battery module. Implementation

[0041] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other. Example

[0042] A porous force-sensitive material, said porous force-sensitive material being made from the following raw materials:

[0043] Sodium phosphate 1 g, polyvinyl alcohol 6 g, glycerol 2.5 g, nano bismuth telluride 0.5 g;

[0044] The structure of the porous force-sensitive material made from the above-mentioned raw materials is as follows: Figure 2As shown, it consists of an alcohol-based matrix 1, random pores 2, and bismuth telluride nanoparticles 3; the size of the random pores is normally distributed, ranging from 30 to 200 μm.

[0045] For the preparation method of the above-mentioned porous force-sensitive material, please refer to [link / reference]. Figure 1 It includes the following steps:

[0046] First, using water (28 g) as the dissolving and dispersing medium, 1 g of sodium phosphate and 6 g of polyvinyl alcohol were dissolved by low-speed stirring at 90°C with a stirring speed of about 300 rpm and a stirring time of 1 h.

[0047] (2) Then, glycerol (2.5 g) was mixed into the solution and stirred (300 rpm, 1 h) to form an aqueous ionic gel solution;

[0048] (3) Subsequently, the aqueous ionic gel solution and bismuth telluride nanoparticles (0.5 g) were mechanically stirred and dispersed at 300 rpm;

[0049] (4) Then, mechanical stirring (2000 rpm) is used to form a foam fluid and coated into a thin layer (thickness ~1 mm).

[0050] (5) Finally, during the curing and film formation stage, the medium water is evaporated by baking (60 °C, 3 h) to retain the alcohol ion gel porous foam film.

[0051] The flexible pressure sensor prepared using the above materials has the following structure: Figure 3 As shown, conductive fabric serves as the upper electrode 4 and the lower electrode 5, and the aforementioned porous force-sensitive material serves as the intermediate force-sensitive layer 6.

[0052] The structure of the smart insole further prepared using the aforementioned flexible pressure sensor is as follows: Figure 4 As shown, it includes a substrate 8, in which seven flexible pressure sensors 7 as described above are embedded, and also includes a signal processing module 9, a wireless transmission module 10 and a power supply module 11 electrically connected to the flexible pressure sensors 7.

[0053] The aforementioned smart insoles underwent low-temperature resistance testing and measurement range testing.

[0054] The process of low-temperature resistance testing:

[0055] ① Ensure the device is in the off state;

[0056] ② Adjust the air temperature inside the test chamber to the low-temperature storage temperature (-30 ℃);

[0057] ③ After the sample temperature stabilizes, maintain this storage temperature for 24 hours;

[0058] ④ Conduct a comprehensive visual inspection of the equipment and record the inspection results;

[0059] ⑤ Conduct performance tests on the equipment and record the results;

[0060] ⑥ Compare these data with the data from before the experiment.

[0061] The sensor's measurement range was tested using a universal tensile and compressive testing machine and an LCR meter.

[0062] Low temperature resistance test results: After 24 hours at -30℃, the sensing performance of the device did not show significant attenuation, demonstrating good low temperature resistance; the measurement range is 0~5 MPa. Example

[0063] Compared with Example 1, the only difference in this embodiment is the raw material composition of the porous force-sensitive material. The raw material composition of this embodiment is: phosphoric acid, polyvinyl alcohol, methyl silicone oil, and bismuth telluride nanoparticles. The rest is the same as in Example 1.

[0064] First, using water (28 g) as the dissolving and dispersing medium, 1 g of phosphoric acid and 6 g of polyvinyl alcohol were dissolved at 90°C with low-speed stirring at a speed of about 300 rpm for 1 h.

[0065] (2) Then, methyl silicone oil (2.5 g) was mixed into the solution and stirred (300 rpm, 1 h) to form an aqueous ionic gel solution;

[0066] (3) Subsequently, the aqueous ionic gel solution and bismuth telluride nanoparticles (0.5 g) were mechanically stirred and dispersed at 300 rpm;

[0067] (4) Then, mechanical stirring (2000 rpm) is used to form a foam fluid and coated into a thin layer (thickness ~1 mm).

[0068] (5) Finally, during the curing and film formation stage, the medium water is evaporated by baking (60 °C, 3 h) to retain the alcohol ion gel porous foam film.

[0069] Low temperature resistance test results: After 24 hours at -30℃, the sensing performance of the device did not show significant attenuation, demonstrating good low temperature resistance; the measurement range is 0~5 MPa. Example

[0070] Compared with Example 1, this example uses 1.5 g of sodium phosphate, 5.5 g of polyvinyl alcohol, 2.5 g of glycerol, and 0.5 g of nano-bismuth telluride, with the rest being the same as in Example 1.

[0071] Low temperature resistance test results: After 24 hours at -30℃, the sensing performance of the device did not show significant attenuation, demonstrating good low temperature resistance; the measurement range is 0~5 MPa. Example

[0072] Compared with Example 1, this example uses 0.5 g of sodium phosphate, 5.5 g of polyvinyl alcohol, 3.5 g of glycerol, and 0.5 g of nano-bismuth telluride, while the rest is the same as in Example 1.

[0073] Low temperature resistance test results: After 24 hours at -30℃, the sensing performance of the device did not show significant attenuation, demonstrating good low temperature resistance; the measurement range is 0~5 MPa. Example

[0074] Compared with Example 1, the only difference in this embodiment is that the mechanical stirring speed in step (4) of the preparation process of the porous force-sensitive material is 1500 rpm. The rest is the same as in Example 1, that is:

[0075] First, using water (28 g) as the dissolving and dispersing medium, 2 g of sodium phosphate and 4 g of polyvinyl alcohol were dissolved by low-speed stirring at 90°C with a stirring speed of about 300 rpm and a stirring time of 1 h.

[0076] (2) Then, glycerol (7 g) was mixed into the solution and stirred (300 rpm, 1 h) to form an aqueous ionic gel solution;

[0077] (3) Subsequently, the aqueous ionic gel solution and bismuth telluride nanoparticles (2 g) were mechanically stirred and dispersed at 300 rpm;

[0078] (4) Then, mechanical stirring (1500 rpm) is used to form a foam fluid and coated into a thin layer (thickness ~1 mm).

[0079] (5) Finally, during the curing and film formation stage, the medium water is evaporated by baking (60 °C, 3 h) to retain the alcohol ion gel porous foam film.

[0080] Low temperature resistance test results: After 24 hours at -30℃, the sensing performance of the device did not show significant attenuation, indicating good low temperature resistance; the measurement range is 0~4 MPa. Example

[0081] Compared with Example 1, the only difference in this embodiment is that the curing time in step (5) of the porous force-sensitive material preparation process is 2 hours. The rest is the same as in Example 1, namely:

[0082] First, using water (28 g) as the dissolving and dispersing medium, 2 g of sodium phosphate and 4 g of polyvinyl alcohol were dissolved by low-speed stirring at 90°C with a stirring speed of about 300 rpm and a stirring time of 1 h.

[0083] (2) Then, glycerol (7 g) was mixed into the solution and stirred (300 rpm, 1 h) to form an aqueous ionic gel solution;

[0084] (3) Subsequently, the aqueous ionic gel solution and bismuth telluride nanoparticles (2 g) were mechanically stirred and dispersed at 300 rpm;

[0085] (4) Then, mechanical stirring (2000 rpm) is used to form a foam fluid and coated into a thin layer (thickness ~1 mm).

[0086] (5) Finally, during the curing and film formation stage, the medium water is evaporated by baking (60 °C, 1 h) to retain the alcohol ion gel porous foam film.

[0087] Low temperature resistance test results: After 24 hours at -30℃, the sensing performance of the device did not show significant attenuation, demonstrating good low temperature resistance; the measurement range is 0~5 MPa.

[0088] Comparative Example 1

[0089] Compared with Example 1, the only difference in this embodiment is that the curing time in step (5) of the porous force-sensitive material preparation process is 30 min, while the rest is the same as in Example 1.

[0090] (1) First, water (28 g) was used as the dissolving and dispersing medium. At 90°, 2 g of sodium phosphate and 4 g of polyvinyl alcohol were dissolved by low-speed stirring. The stirring speed was about 300 rpm and the stirring time was 1 h.

[0091] (2) Then, glycerol (7 g) was mixed into the solution and stirred (300 rpm, 1 h) to form an aqueous ionic gel solution;

[0092] (3) Subsequently, the aqueous ionic gel solution and bismuth telluride nanoparticles (2 g) were mechanically stirred and dispersed at 300 rpm;

[0093] (4) Then, mechanical stirring (2000 rpm) is used to form a foam fluid and coated into a thin layer (thickness ~1 mm).

[0094] (5) Finally, during the curing and film formation stage, the medium water is evaporated by baking (60 °C, 30 min) to retain the alcohol ion gel porous foam film.

[0095] The sample exhibits an unrecoverable force response due to incomplete evaporation of moisture.

[0096] Comparative Example 2

[0097] Compared with Example 1, the only difference in this embodiment is that the stirring speed in step (5) of the preparation process of the porous force-sensitive material is 500 rpm. The rest is the same as in Example 1, that is:

[0098] (1) First, water (28 g) was used as the dissolving and dispersing medium. At 90°, 2 g of sodium phosphate and 4 g of polyvinyl alcohol were dissolved by low-speed stirring. The stirring speed was about 300 rpm and the stirring time was 1 h.

[0099] (2) Then, glycerol (7 g) was mixed into the solution and stirred (300 rpm, 1 h) to form an aqueous ionic gel solution;

[0100] (3) Subsequently, the aqueous ionic gel solution and bismuth telluride nanoparticles (2 g) were mechanically stirred and dispersed at 300 rpm;

[0101] (4) Then, mechanical stirring (500 rpm) is used to form a foam fluid and coated into a thin layer (thickness ~1 mm).

[0102] (5) Finally, during the curing and film formation stage, the medium water is evaporated by baking (60 °C, 3 h) to retain the alcohol ion gel porous foam film.

[0103] The sample could not form uniform small bubbles due to the slow stirring speed, and therefore a foam force-sensitive film could not be obtained.

[0104] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A porous force-sensitive material, characterized in that, The porous force-sensitive material is made from the following raw materials in the following mass percentages: Ionic electrolyte 5%–15%, polyvinyl alcohol 35%–65%, polyol 15%–25%, nano-bismuth telluride 5%–10%; A porous force-sensitive material composed of an alcohol matrix, random pores, and bismuth telluride nanoparticles was prepared using the above-mentioned raw materials. Its preparation method includes the following steps: (1) First, water is used as the dissolving and dispersing medium to dissolve the ionic electrolyte and polyvinyl alcohol; (2) Then, it is mixed with polyol to form an aqueous ionic gel solution; (3) Subsequently, the aqueous ionic gel solution and nano-bismuth telluride particles are mechanically stirred and dispersed. (4) Then, mechanical stirring is used to form a foam fluid and coated into a thin layer; the mechanical stirring is 1500 rpm to 3000 rpm; (5) Finally, the film is cured by baking and evaporating the medium water and curing it, retaining the alcohol ion gel porous foam film. The baking temperature is 60-80°C and the baking time is 1-5 h. The ionic electrolyte is sodium phosphate, and the polyol is glycerol.

2. A flexible pressure sensor, characterized in that, The flexible pressure sensor uses conductive fabric as the upper and lower electrodes, and the porous force-sensitive material described in claim 1 as the middle force-sensitive layer.

3. A wearable smart insole for use in high-altitude environments, characterized in that, The insole includes at least two flexible pressure sensors as described in claim 2, and further includes a signal processing module, a wireless transmission module, and a power supply module electrically connected to the flexible pressure sensors.

4. The wearable smart insole for high-altitude environments according to claim 3, characterized in that, The number of pressure sensors in a single insole ranges from 5 to 50.

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