A leather-based flexible capacitive pressure sensor and a method of manufacturing the same

Abstract

The present application belongs to the technical field of flexible electronics, and particularly relates to a leather-based flexible capacitive pressure sensor and a preparation method thereof. The sensor integrates a dielectric layer and an electrode layer. The method uses the thickness and natural hierarchical structure of leather to realize the leather-based flexible capacitive pressure sensor integrating the dielectric layer and the electrode layer. First, based on the tanning theory, zirconium salt is selected to modify the leather collagen fiber. Zirconium ions interact with the leather collagen fiber, enhance the polarity of the leather collagen fiber, increase the dielectric constant of the whole leather, and thus improve the dielectric property of the leather, which is used as the dielectric layer of the sensor. Then, pyrrole is selected to in-situ polymerize polypyrrole on the upper layer of the nipple layer and the lower layer of the reticular layer of the leather, so as to endow the leather with excellent conductivity, which is used as the electrode layer of the sensor, and thus the leather-based flexible capacitive pressure sensor integrating the dielectric layer and the electrode layer is obtained.

Description

Technical Field

[0001] This invention belongs to the field of flexible electronics technology, specifically relating to a leather-based flexible capacitive pressure sensor and its fabrication method. Background Technology

[0002] Leather is a biomass material woven from collagen fibers, composed of a papillary layer and a reticular layer, possessing excellent elasticity, biocompatibility, flexibility, and mechanical strength. Polypyrrole is a simple and environmentally friendly conductive polymer with high electrical conductivity, commonly used in the fabrication of electrode layers for flexible capacitive pressure sensors.

[0003] With the rapid development of artificial intelligence technology, flexible pressure sensors, as autonomous input devices for intelligent detection equipment, have received widespread attention in wearable electronic devices such as motion detection, healthcare, and human-computer interaction. Among them, flexible capacitive pressure sensors, composed of a dielectric layer and an electrode layer, can convert external force signals into capacitive signal outputs, offering advantages such as simple structure, high sensitivity, and fast response speed. However, these sensors suffer from poor adhesion between the dielectric and electrode layers and weak interfacial bonding, leading to unstable sensing performance and a tendency to fail.

[0004] Therefore, developing flexible capacitive pressure sensors that integrate dielectric and electrode layers has become a new challenge and opportunity in the field of flexible electronics technology. Summary of the Invention

[0005] This invention proposes a leather-based flexible capacitive pressure sensor and its fabrication method, aiming to solve the problem of poor adhesion and weak interfacial bonding between the dielectric layer and electrode layer in existing flexible capacitive pressure sensors, which leads to unstable sensing performance.

[0006] The technical solution adopted in this invention is as follows:

[0007] A method for fabricating a leather-based flexible capacitive pressure sensor: using zirconium salt-modified leather collagen fibers as the dielectric layer, polypyrrole is in-situ polymerized and grown on the upper layer of the papillary layer and the lower layer of the mesh layer of the leather as the electrode layer, and external wires are attached to both sides of the electrode layer to assemble the flexible capacitive pressure sensor.

[0008] Furthermore, the above method includes the following steps:

[0009] (1) Preparation of dielectric layer: Zirconium sulfate tetrahydrate Zr(SO4)2·4H2O was dissolved in a certain amount of deionized water. Leather was added to the Zr(SO4)2·4H2O solution and reacted at 25℃ and 10.5r / min for 30min. A certain amount of formic acid solution was added to the system every 15min until the pH was 2.0. After reacting for 4h, a certain amount of sodium bicarbonate solution was added to the system every 15min until the pH was 3.0. The temperature was raised to 40℃ and reacted for 30-40min. The temperature and speed were turned off and the reaction was carried out for 12h. The temperature was raised to 40℃ and reacted for 30min to obtain zirconium salt modified leather collagen fiber, which was used as the dielectric layer of the sensor.

[0010] (2) Electrode layer preparation: 0.5-2.0g of pyrrole (Py) was dispersed in ice water and magnetically stirred for 30-60min to obtain a Py solution; the zirconium salt modified leather collagen fiber prepared in step (1) was added to the Py solution, and 10.0-15.0g of ferric chloride hexahydrate (FeCl3·6H2O) was dissolved in deionized water and then placed in a constant pressure separatory funnel and slowly added to the Py solution. After the addition was completed, the reaction was carried out for 120-180min to obtain polypyrrole modified leather, which was used as the electrode layer of the sensor.

[0011] (3) Assembly of flexible capacitive pressure sensor: Wires are attached to both sides of the electrode layer of the sensing material, and then encapsulated with bio-permeable tape to obtain a leather-based flexible capacitive pressure sensor that integrates the dielectric layer and the electrode layer.

[0012] A leather-based flexible capacitive pressure sensor prepared according to any of the above methods.

[0013] The beneficial effects of this invention are as follows:

[0014] 1. The method for preparing a leather-based flexible capacitive pressure sensor provided by this invention firstly involves modifying leather collagen fibers with zirconium salts to achieve the interaction between zirconium ions and the leather collagen fibers, significantly improving the overall dielectric constant of the leather and thus enhancing its dielectric properties. This modified leather serves as the dielectric layer of the sensor. Further, pyrrole is selected and grown in situ through polymerization on the upper layer of the leather papillary layer and the lower layer of the reticular layer, forming a uniform conductive coating on its surface. This coating serves as the electrode layer of the sensor, resulting in a leather-based flexible capacitive pressure sensor integrating both the dielectric and electrode layers. This method solves the problems of poor adhesion and weak interfacial bonding between the dielectric and electrode layers in flexible capacitive pressure sensors, thereby improving the sensing performance and stability of the flexible capacitive pressure sensor.

[0015] 2. The leather-based flexible capacitive pressure sensor provided by the present invention integrates the dielectric layer and the electrode layer into one unit. Compared with the non-integrated type, the signal strength of the integrated flexible capacitive pressure sensor is significantly improved by 5 to 10 times, and the sensor can still maintain stable sensing performance after repeated cyclic friction or bending operations. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the invention clearer, the invention will be further described in detail below with reference to embodiments.

[0017] A method for fabricating a leather-based flexible capacitive pressure sensor: using zirconium salt-modified leather collagen fibers as the dielectric layer, polypyrrole is in-situ polymerized and grown on the upper layer of the papillary layer and the lower layer of the mesh layer of the leather as the electrode layer, and external wires are attached to both sides of the electrode layer to assemble the flexible capacitive pressure sensor. The specific steps include:

[0018] (1) Preparation of dielectric layer: Zirconium sulfate tetrahydrate Zr(SO4)2·4H2O was dissolved in a certain amount of deionized water. Leather was added to the Zr(SO4)2·4H2O solution and reacted at 25℃ and 10.5r / min for 30min. A certain amount of formic acid solution was added to the system every 15min until the pH was 2.0. After reacting for 4h, a certain amount of sodium bicarbonate solution was added to the system every 15min until the pH was 3.0. The temperature was raised to 40℃ and reacted for 30-40min. The temperature and speed were turned off and the reaction was carried out for 12h. The temperature was raised to 40℃ and reacted for 30min to obtain zirconium salt modified leather collagen fiber, which was used as the dielectric layer of the sensor.

[0019] (2) Electrode layer preparation: 0.5-2.0g of pyrrole (Py) was dispersed in ice water and magnetically stirred for 30-60min to obtain a Py solution; the zirconium salt modified leather collagen fiber prepared in step (1) was added to the Py solution, and 10.0-15.0g of ferric chloride hexahydrate (FeCl3·6H2O) was dissolved in deionized water and then placed in a constant pressure separatory funnel and slowly added to the Py solution. After the addition was completed, the reaction was carried out for 120-180min to obtain polypyrrole modified leather, which was used as the electrode layer of the sensor.

[0020] (3) Assembly of flexible capacitive pressure sensor: Wires are attached to both sides of the electrode layer of the sensing material, and then encapsulated with bio-permeable tape to obtain a leather-based flexible capacitive pressure sensor that integrates the dielectric layer and the electrode layer.

[0021] Example 1

[0022] A method for fabricating a leather-based flexible capacitive pressure sensor includes the following steps:

[0023] (1) Preparation of dielectric layer: Zirconium sulfate tetrahydrate (Zr(SO4)2·4H2O) was dissolved in a certain amount of deionized water. Leather was added to the Zr(SO4)2·4H2O solution and reacted at 25℃ and 10.5r / min for 30min. A certain amount of formic acid solution was added to the system every 15min until the pH was 2.0. After reacting for 4h, a certain amount of sodium bicarbonate solution was added to the system every 15min until the pH was 3.0. The temperature was raised to 40℃ and reacted for 30-40min. The temperature and speed were turned off and the reaction was carried out for 12h. The temperature was raised to 40℃ and reacted for 30min to obtain zirconium salt modified leather collagen fiber, which can be used as the dielectric layer of sensor.

[0024] (2) Electrode layer preparation: 0.7g pyrrole (Py) was dispersed in ice water and magnetically stirred for 60min to obtain Py solution; the zirconium salt modified leather collagen fiber prepared in operation (1) was added to Py solution, 10.8g ferric chloride hexahydrate (FeCl3·6H2O) oxidant was dissolved in deionized water, and then placed in a constant pressure separatory funnel and slowly dripped into Py solution. After the dripping was completed, the reaction was carried out for 120min to obtain polypyrrole modified leather with excellent conductivity on both sides, which can be used as the electrode layer of sensor;

[0025] (3) Assemble the flexible capacitive pressure sensor: attach wires to both sides of the electrode layer of the sensing material, and then encapsulate it with bio-permeable tape to obtain a leather-based flexible capacitive pressure sensor that integrates the dielectric layer and the electrode layer.

[0026] Example 2

[0027] A method for fabricating a leather-based flexible capacitive pressure sensor includes the following steps:

[0028] (1) Preparation of dielectric layer: Zirconium sulfate tetrahydrate (Zr(SO4)2·4H2O) was dissolved in a certain amount of deionized water. Leather was added to the Zr(SO4)2·4H2O solution and reacted at 25℃ and 10.5r / min for 30min. A certain amount of formic acid solution was added to the system every 15min until the pH was 2.0. After reacting for 4h, a certain amount of sodium bicarbonate solution was added to the system every 15min until the pH was 3.0. The temperature was raised to 40℃ and reacted for 30-40min. The temperature and speed were turned off and the reaction was carried out for 12h. The temperature was raised to 40℃ and reacted for 30min to obtain zirconium salt modified leather collagen fiber, which can be used as the dielectric layer of sensor.

[0029] (2) Electrode layer preparation: 2.0 g of pyrrole (Py) was dispersed in ice water and magnetically stirred for 30 min to obtain a Py solution; the zirconium salt modified leather collagen fiber prepared in operation (1) was added to the Py solution, and 13.5 g of ferric chloride hexahydrate (FeCl3·6H2O) was dissolved in deionized water and then placed in a constant pressure separatory funnel and slowly added to the Py solution. After the addition was completed, the reaction was carried out for 180 min to obtain polypyrrole modified leather with excellent conductivity on both sides, which can be used as the electrode layer of the sensor.

[0030] (3) Assemble the flexible capacitive pressure sensor: attach wires to both sides of the electrode layer of the sensing material, and then encapsulate it with bio-permeable tape to obtain a leather-based flexible capacitive pressure sensor that integrates the dielectric layer and the electrode layer.

[0031] The embodiments described above are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A method for fabricating a leather-based flexible capacitive pressure sensor, characterized in that: A flexible capacitive pressure sensor is assembled by using zirconium salt modified leather collagen fiber as the dielectric layer, and polypyrrole is grown in situ on the upper layer of the papillary layer and the lower layer of the reticular layer of the leather as the electrode layer. External wires are attached to both sides of the electrode layer. Specifically, the following steps are included: (1) Preparation of dielectric layer: Zirconium sulfate tetrahydrate Zr(SO4)2·4H2O was dissolved in a certain amount of deionized water. Leather was added to the Zr(SO4)2·4H2O solution and reacted at 25℃ and 10.5r / min for 30 min. A certain amount of formic acid solution was added to the system every 15 min until the pH was 2.

0. After reacting for 4 h, a certain amount of sodium bicarbonate solution was added to the system every 15 min until the pH was 3.

0. The temperature was raised to 40℃ and reacted for 30 ~ 40 min. The temperature and speed were turned off and the reaction was carried out for 12 h. The temperature was raised to 40℃ and reacted for 30 min to obtain zirconium salt modified leather collagen fiber, which was used as the dielectric layer of the sensor. (2) Electrode layer preparation: 0.5 ~ 2.0 g of pyrrole Py was dispersed in ice water and magnetically stirred for 30 ~ 60 min to obtain Py solution; the zirconium salt modified leather collagen fiber prepared in step (1) was added to the Py solution, and 10.0 ~ 15.0 g of ferric chloride hexahydrate FeCl3·6H2O was dissolved in deionized water and then placed in a constant pressure separatory funnel and slowly added to the Py solution. After the addition was completed, the reaction was carried out for 120 ~ 180 min to obtain polypyrrole modified leather, which was used as the electrode layer of the sensor. (3) Assembly of flexible capacitive pressure sensor: attach wires to both sides of the electrode layer of the sensing material, and then encapsulate with bio-permeable tape to obtain a leather-based flexible capacitive pressure sensor that integrates the dielectric layer and the electrode layer.

2. A leather-based flexible capacitive pressure sensor prepared by the method described in claim 1.