CN115808235A

CN115808235A - Preparation method of flexible wearable piezoresistive sensor based on polypyrrole

Info

Publication number: CN115808235A
Application number: CN202211467214.0A
Authority: CN
Inventors: 翁凌; 吴迪; 李宇寒; 关丽珠
Original assignee: Harbin University of Science and Technology
Current assignee: Harbin University of Science and Technology
Priority date: 2022-11-22
Filing date: 2022-11-22
Publication date: 2023-03-17

Abstract

A preparation method of a flexible wearable piezoresistive sensor based on polypyrrole belongs to the field of wearable piezoresistive sensors. The method takes pyrrole and sodium p-toluenesulfonate as raw materials, prepares the polypyrrole film by an electrochemical method, then uses a commercially available 3M adhesive tape to carry out biaxial stretching on the polypyrrole film, and then sticks the polypyrrole film on the polypyrrole film to prepare the folded structure film. And finally, packaging the flexible wearable piezoresistive sensor by using 3M adhesive tape and PDMS to obtain the flexible wearable piezoresistive sensor based on the polypyrrole. The invention improves the performance of the sensor well by constructing the micro-fold structure. When the sensor is compressed and deformed, the upper electrode and the lower electrode are changed from point contact to surface contact, a large number of new conductive paths are formed, and the resistance value of the sensor is reduced. The sensor provided by the invention has the advantages of simple preparation method, low cost and excellent performance, and has great development potential in the fields of health monitoring, motion monitoring, artificial intelligence, wearable equipment, man-machine interaction and the like.

Description

Preparation method of flexible wearable piezoresistive sensor based on polypyrrole

Technical Field

The invention belongs to the field of wearable piezoresistive sensors; in particular to a preparation method of a flexible wearable piezoresistive sensor based on polypyrrole; the flexible wearable piezoresistive sensor based on polypyrrole is mainly used in the fields of health monitoring, motion monitoring, artificial intelligence, wearable equipment, man-machine interaction and the like.

Background

In recent years, with the progress of modern technology and the improvement of living standard of people, the demand of people for flexible wearable sensors is increasing. Piezoresistive sensors have the advantages of simple preparation, low cost, excellent performance and the like, have wide application in the fields of health monitoring, motion monitoring, artificial intelligence, wearable electronic equipment, man-machine interaction and the like, and are increasingly attracted by scientific researchers. However, the conventional flexible wearable piezoresistive sensor still has the problems of low sensitivity, slow response speed, poor cycle stability, poor wearability, poor compatibility with a human body and the like, and the application of the flexible piezoresistive sensor is severely limited.

In order to improve the performance of flexible piezoresistive sensors, researchers have designed a variety of microstructures such as micro-dome/micro-pyramid arrays, interlocking structures, leaf/petal stamping patterns, corrugated structures, and the like. Among them, the pleated structure is receiving increasing attention from researchers due to its excellent properties.

Various conductive materials are also applied in the design of sensors, and the tried conductive materials are mainly carbon materials (carbon black, carbon nanotubes, graphene, etc.), metal nanomaterials (metal nanowires, metal nanoparticles, etc.), MXene, metal organic frameworks, conductive polymers, and the like. Polypyrrole is a typical conductive polymer, has the advantages of good air stability, easiness in electrochemical polymerization to form a film, high conductivity, good mechanical property, no toxicity and the like, and is very suitable for manufacturing flexible piezoresistive sensors.

PDMS has the advantages of good human body compatibility, no toxicity, no harm, excellent mechanical property, easy preparation and the like, and is very suitable for serving as a packaging material of a flexible wearable sensor.

Disclosure of Invention

The flexible wearable piezoresistive sensor based on polypyrrole, which is prepared by the invention, has the advantages of high sensitivity, low hysteresis, good circulation stability, good human body compatibility and the like through tests, and has great development potential in the fields of health monitoring, motion monitoring, artificial intelligence, wearable equipment, human-computer interaction and the like.

In order to achieve the purpose, the preparation method of the flexible wearable piezoresistive sensor based on polypyrrole in the invention comprises the following steps:

step one, pre-stretching a 3M adhesive tape (3M 4910VHB adhesive tape, a commercially available commodity), and then carrying out hydrophilic treatment;

adhering the polypyrrole film on a hydrophilic treated 3M adhesive tape, releasing pre-stretching, obtaining a fold structure film on the 3M adhesive tape, and then cutting the fold structure film into two pieces with the same size to obtain two electrodes;

bonding a copper wire on the two electrodes by using conductive silver adhesive, bonding the copper wire on the folded structure film, and then bonding a new 3M adhesive tape on one side of the 3M adhesive tape;

fourthly, placing the folds face to face, staggering the copper wires, sticking the copper wires together, coating a layer of PDMS on the surface, curing, and cooling to room temperature to obtain the sensor;

wherein, the copper wire of step three is the copper wire of removal insulating layer, and new 3M sticky tape size guarantees to cover the electrode.

Further defined, the polypyrrole film in the first step is prepared by the following steps:

step 1, adding pyrrole and sodium p-toluenesulfonate into deionized water, and uniformly stirring;

and 2, carrying out reaction by using an electrochemical method, after the reaction is finished, drying in an oven at 60 ℃, taking out after 10min, cooling to room temperature, and stripping the polypyrrole film on the electrode to obtain the polypyrrole film.

Further defined, the concentration of pyrrole in step 1 is 0.05M-0.2M, and the concentration of sodium p-toluenesulfonate is 0.05M-0.5M.

Further limited, in the step 2, the electrochemical method uses constant current polarization, the polarization current is 5mA-20mA, the reaction time is 15min-90min, the electrode is a stainless steel sheet, the area is 16cm-100cm, and the polar distance is 0.5cm-4cm.

Further defined, the pre-stretching in the first step is uniaxial stretching or biaxial stretching, and the stretching amplitude is 50-200%.

Further defined, the pre-stretching in the first step is biaxial stretching, and the stretching amplitude is 100%.

Further defined, the hydrophilic treatment in the first step is a plasma treatment or a silane coupling agent treatment.

Further defined, the 3M tape thickness in steps one and three was 1mm.

Further limiting, the shape of the electrode in the second step is a square with the side length of 0.8cm-1.6 cm.

Further defined, the curing is carried out at 110 ℃ for 10min in the fourth step.

The flexible wearable piezoresistive sensor based on polypyrrole, which is prepared by the method, is mainly applied to the fields of health monitoring, motion monitoring, artificial intelligence, wearable equipment, man-machine interaction and the like.

In general, compared with the prior art, the flexible wearable piezoresistive sensor designed by the invention can achieve the following beneficial effects:

the polypyrrole film prepared by the invention has the advantages of excellent conductivity, good flexibility, good mechanical strength, simple preparation method, large-scale preparation, low cost, environmental protection, no toxicity, no harm and the like, and is suitable for preparing wearable flexible piezoresistive sensors.

Due to the existence of the micro-fold structure, when the sensor is compressed, the upper electrode and the lower electrode are in point contact and surface contact, a large number of new conductive paths are formed, and the resistance value of the sensor is reduced. The method for preparing the fold structure is simple and economic, is easy to prepare, has ideal size and scale of the micro-folds, and well improves the performance of the sensor. Due to the existence of the 3M adhesive tape, the electrode with the folded structure has good resilience, and the sensitivity and the detection range of the electrode are increased.

The invention uses 3M adhesive tape and PDMS for packaging, is simple and economical, and improves the performance and stability of the sensor. The PDMS has the advantages of good compatibility with human bodies, no toxicity, no harm, excellent mechanical property, easy preparation and the like, so that the sensor is suitable for application of wearable devices.

The invention improves the performance of the sensor well by constructing the micro-fold structure. When the sensor is compressed and deformed, the upper electrode and the lower electrode are changed from point contact to surface contact, a large number of new conductive paths are formed, and the resistance value of the sensor is reduced. The sensor designed by the invention has the advantages of simple preparation method, low cost and excellent performance, and has great development potential in the fields of health monitoring, motion monitoring, artificial intelligence, wearable equipment, man-machine interaction and the like.

For a better understanding of the nature and technical content of the present invention, reference should be made to the following detailed description of the invention and to the accompanying drawings, which are provided for purposes of illustration and description only and are not intended to be limiting.

Drawings

FIG. 1 is a polypyrrole-based flexible wearable piezoresistive sensor Δ R/R0-pressure test made by the method of example 1;

FIG. 2 is SEM images of the surface of the polypyrrole pleating structure film prepared by the method of example 1, wherein a is magnified 125 times, b is magnified 250 times, and c is magnified 350 times;

FIG. 3 is SEM images of polypyrrole pleated structure thin film prepared by the method of example 1, wherein a is enlarged 130 times and b is enlarged 250 times.

FIG. 4 is a diagram of polypyrrole based flexible wearable piezoresistive sensor pulse monitoring made by the method of example 1;

FIG. 5 illustrates a polypyrrole-based Flexible wearable piezoresistive transducer, a-Technology, b-flexile, c-Hello, fabricated by the method of example 1.

Detailed Description

The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

The following examples used 3M adhesive tape with a thickness of 1mm.

Example 1:

the preparation method of the polypyrrole film in the embodiment is carried out according to the following steps:

step one, weighing 1.3550g of pyrrole and 6.8449g of p-toluenesulfonic acid, adding into 200mL of deionized water, and uniformly stirring;

and step two, carrying out reaction by using an electrochemical method, and polarizing by using constant current, wherein the polarizing current is 10mA. The reaction time was 60 minutes. The electrode is a stainless steel sheet with an area of 5X 5cm. The pole pitch was 1cm.

Step three, after the reaction is finished, putting the mixture into a 60 ℃ oven for drying, taking out the mixture after 10min, and cooling the mixture to room temperature;

and step four, carefully peeling the polypyrrole film on the stainless steel sheet from the periphery by using a wallpaper knife, and finishing the preparation of the polypyrrole film.

Then preparing the polypyrrole wrinkle structure film by using the polypyrrole film prepared by the method, wherein the preparation method is specifically completed by the following steps:

step one, cutting a purchased 3M4910VHB adhesive tape (namely 3M adhesive tape) into a size of 10cm multiplied by 10cm, and then performing pre-stretching on the adhesive tape, wherein the pre-stretching is biaxial stretching, and the stretching amplitude is 100%;

and (II) adhering the polypyrrole film to the 3M adhesive tape, and finally releasing the pre-stretched 3M adhesive tape to obtain the film with the fold structure on the 3M adhesive tape.

The polypyrrole wrinkled structure film prepared by the method is used for packaging a sensor and is specifically completed by the following steps:

step 1, cutting the effective parts of the prepared polypyrrole fold structure film into two pieces with the same size of 1cm multiplied by 1cm, and meanwhile, leaving a section of lead-out part for connecting a copper wire to obtain two electrodes;

2, polishing two ends of a soft copper wire by using sand paper to remove an insulating layer of the soft copper wire, fixing the soft copper wire on the leading-out parts of the two electrodes by using a small amount of conductive silver paste, and curing the soft copper wire in a 110 ℃ oven for 10 minutes to complete the connection of the wire;

step 3, aligning the centers of two polypyrrole wrinkle structure electrodes connected with leads to one side of a 3M adhesive tape, sticking a new 3M adhesive tape (12 cm multiplied by 12 cm), placing the wrinkle surfaces of the two electrodes in a staggered manner, and sticking the copper leads together;

and 4, coating a layer of PDMS on the upper surface and the lower surface of the adhered sensor, curing the PDMS in a 110 ℃ oven for 10 minutes, taking out the PDMS, and cooling the PDMS to room temperature in a natural environment to complete the packaging of the sensor.

The Δ R/R0-pressure test of the flexible wearable piezoresistive sensor based on polypyrrole prepared in this example is shown in fig. 1, and it can be known from fig. 1 that the sensitivity of the flexible wearable piezoresistive sensor based on polypyrrole prepared in this example is large when the strain is small; when the strain is medium, the value is medium; at high strains, the values are small.

The SEM images of different magnifications of the surface of the polypyrrole pleated membrane prepared in this example are shown in fig. 2, and as can be seen from fig. 2, the surface of the polypyrrole pleated membrane prepared in this example has uniform pleat morphology and ideal amplitude.

An SEM image of the polypyrrole pleating structure thin film prepared in this example with different magnifications is shown in fig. 3, and as can be seen from fig. 3, the cross section of the polypyrrole pleating structure thin film prepared in this example has uniform micro-morphology and ideal amplitude.

As shown in fig. 4, it can be seen from fig. 4 that the flexible wearable piezoresistive sensor based on polypyrrole prepared in this embodiment can well reflect the fluctuation of human pulse through the change of resistance.

As shown in fig. 5, it can be known from fig. 5 that the flexible wearable piezoresistive sensor based on polypyrrole prepared in this embodiment can well reflect the voice condition of a human body through the change of resistance.

Example 2:

and step two, carrying out reaction by using an electrochemical method, and carrying out polarization by using constant current, wherein the polarization current is 5mA, the reaction time is 120 minutes, the electrode is a stainless steel sheet, and the area is 5 multiplied by 5cm. The pole pitch was 1cm.

and step four, carefully peeling the polypyrrole film on the stainless steel sheet from the periphery by using a wallpaper knife, and thus finishing the preparation of the polypyrrole film.

step one, cutting a purchased 3M4910VHB adhesive tape (namely 3M adhesive tape) into a size of 10 multiplied by 10cm, and then performing pre-stretching, wherein the pre-stretching is biaxial stretching, and the stretching amplitude is 50%;

and (II) adhering the polypyrrole film on the 3M adhesive tape, and finally releasing the pre-stretched 3M adhesive tape to obtain the film with the fold structure on the 3M adhesive tape.

step 1, cutting the effective parts of the prepared polypyrrole fold structure film into two pieces with the same size of 1cm multiplied by 1cm, and meanwhile, leaving a section of leading-out part for connecting a copper wire to obtain two electrodes;

and 2, polishing two ends of the soft copper wire by using sand paper to remove the insulating layer. Then fixing the conductive silver paste on the leading-out parts of the two electrodes by using a little conductive silver paste. Curing the mixture in a drying oven at 110 ℃ for 10 minutes to complete the connection of the wires;

and 4, coating a layer of PDMS on the upper surface and the lower surface of the adhered sensor, and curing in an oven at 110 ℃ for 10 minutes. And taking out the sensor, and cooling the sensor to room temperature in a natural environment to finish the packaging of the sensor.

Example 3:

and step two, carrying out reaction by using an electrochemical method, carrying out constant current polarization, wherein the polarization current is 20mA, the reaction time is 40 minutes, the electrode is a stainless steel sheet, and the area is 5cm multiplied by 5cm. The polar distance is 1cm;

step three, after the reaction is finished, putting the mixture into a 60 ℃ oven for drying, taking the mixture out after 10min, and cooling the mixture to room temperature;

and step four, carefully peeling the polypyrrole film on the stainless steel sheet from the periphery by using a wallpaper knife, and finishing the preparation of the polypyrrole film. Then preparing the polypyrrole wrinkle structure film by using the polypyrrole film prepared by the method, wherein the preparation method is specifically completed by the following steps:

cutting a purchased 3M4910VHB (namely 3M adhesive tape) into 10cm multiplied by 10cm, and then performing pre-stretching, wherein the pre-stretching is biaxial stretching, and the stretching amplitude is 150%;

step 1, cutting the effective parts of the prepared polypyrrole fold structure film into two pieces with the same size of 1.2cm multiplied by 1.2cm, and meanwhile, leaving a section of lead-out part for connecting a copper wire to obtain two electrodes;

and 2, polishing two ends of the soft copper wire by using sand paper to remove the insulating layer. Then fixing the conductive silver paste on the leading-out parts of the two electrodes by using a small amount of conductive silver paste. Curing the mixture in a drying oven at 110 ℃ for 10 minutes to complete the connection of the wires;

step 3, aligning the centers of two polypyrrole wrinkle structure electrodes connected with leads to one side of a 3M adhesive tape, sticking a new 3M adhesive tape (12 cm multiplied by 12cm in size), placing the wrinkle surfaces of the two electrodes in a face-to-face mode, staggering copper leads, and sticking the copper leads together;

Claims

1. A preparation method of a flexible wearable piezoresistive sensor based on polypyrrole is characterized by comprising the following steps:

step one, performing hydrophilic treatment after pre-stretching a 3M adhesive tape;

wherein, the copper wire of step three is the copper wire of removal insulating layer, and new 3M sticky tape size is guaranteed to cover the electrode.

2. The method according to claim 1, wherein the polypyrrole film is prepared by the following steps:

3. The process according to claim 2, wherein the concentration of pyrrole in step 1 is 0.05M to 0.2M and the concentration of sodium p-toluenesulfonate is 0.05M to 0.5M.

4. The production method according to claim 2, wherein constant current polarization is used in step 2, the polarization current is 5 to 20mA, the reaction time is 15 to 90 minutes, the electrode is a stainless steel sheet, the area is 16 to 100cm, and the polar distance is 0.5 to 4cm.

5. The method according to claim 1, wherein the pre-stretching in the first step is a uniaxial stretching or a biaxial stretching, and the stretching range is 50% to 200%.

6. The method according to claim 1, wherein the preliminary stretching in the first step is a biaxial stretching with a stretching width of 100%.

7. The method according to claim 1, wherein the hydrophilic treatment in the first step is a plasma treatment or a silane coupling agent treatment.

8. The method of claim 1, wherein the 3M tape thickness in steps one and three is 1mm.

9. The method according to claim 1, wherein the shape of the electrode in the second step is a square having a side of 0.8cm to 1.6 cm.

10. The method of claim 1, wherein the curing is performed at 110 ℃ for 10min in step four.