Preparation method of flexible sensor with sensitivity adjustable in large range

Abstract

The invention discloses a preparation method and application of a flexible sensor with wide-range adjustable sensitivity (GF), and particularly relates to a preparation method of a flexible sensor with wide-range adjustable sensitivity. The shape memory matrix, the conductive nanoparticles and other materials are mixed, so that the shape memory material is conductive, the sensitivity can be adjusted in a large range through the stretching of the repeatable shape memory material, the shape memory material can be suitable for various scenes, and the problems of signal crosstalk of the current sensor, unadjustable sensitivity and the like are solved.

Description

Technical Field

[0001] The invention belongs to the field of flexibility, and in particular relates to a method for preparing a flexible sensor with adjustable sensitivity in a wide range. Background Art

[0002] Flexible sensors refer to sensors made of flexible materials, which have good flexibility, ductility, bendability, etc. Due to the flexible materials and structures, flexible sensors can be arranged arbitrarily according to the application scenarios, which helps to promote the development of health assessment and disease diagnosis technology towards intelligence, remoteness, efficiency, and precision. In terms of sensing mechanism, flexible sensors can be divided into flexible resistive sensors, flexible capacitive sensors, flexible piezoelectric sensors, and flexible inductive sensors. At present, there are also reports on new sensors such as electronic skin and ionic skin. Various sensors are widely used in medical care, electronic products, textiles, aerospace, environmental monitoring and other fields.

[0003] Based on different sensing mechanisms, flexible pressure sensors can be divided into piezoresistive, capacitive, piezoelectric and triboelectric. Among them, the piezoresistive sensor is a sensor that senses force, pressure or weight based on the resistance change of the material. It is made of piezoresistive material, and the resistance value of the material changes when it is subjected to external force. This sensor usually consists of an elastomer and a piezoresistor covered on its surface. When an external force acts on the elastomer, it deforms, thereby changing the resistance value. This sensor has the advantages of simplicity, reliability, compact structure, easy manufacturing and low cost, and is widely used in industrial automation, robot control, medical equipment, household appliances and other fields. The sensitivity of the flexible pressure sensor is one of its main performances, and the performance change of the sensitivity depends on the structural change of the sensor and the change of the conductive properties of the nano-conductive composite material. Today's flexible pressure sensors need to adjust the sensitivity by changing the material preparation formula, and it is difficult to reversibly adjust the sensitivity after the material is prepared. There is a lack of sensors that can reversibly adjust the sensitivity over a wide range. Therefore, the present invention is proposed to solve the above problems. Summary of the invention

[0004] The purpose of the present invention is to solve the problems of the sensitivity of the flexible pressure sensor being unadjustable or the adjustable range being too low, the sensitivity being not high enough, etc. after the material is prepared, and to provide a method for preparing a flexible sensor with adjustable sensitivity over a wide range.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] The present invention provides a method for preparing a flexible sensor with adjustable sensitivity over a wide range, comprising the following steps:

[0007] Step (1): preparing a shape memory material matrix;

[0008] Step (2): grinding and mixing the conductive nanoparticles and the dispersant;

[0009] Step (3): adding the conductive nanoparticles mixed in step (2) into the shape memory material matrix and mixing them thoroughly to obtain a shape memory matrix containing conductive nanoparticles;

[0010] Step (4): vacuum defoaming and thermally polymerizing the shape memory matrix containing the conductive nanoparticles to obtain a shape memory resin-based sensor;

[0011] Preferably, the shape memory matrix includes one or more of polyurethane shape memory resin, polypropylene shape memory resin, polyethylene shape memory resin, and polyester shape memory resin.

[0012] Preferably, the conductive nanoparticles include one of carbon black, carbon nanotubes, graphene, graphene oxide or a mixture thereof.

[0013] Preferably, the dispersant is one or more of octanol polyoxyethylene ether, dodecanol polyoxyethylene ether, nonylbenzene polyoxyethylene ether, octanol polyoxyethylene ether sodium sulfate, and nonyl polyoxyethylene ether.

[0014] Preferably, the curing agent is one or more of benzoyl peroxide, benzoyl peroxide propionic acid, benzoyl peroxide butyric acid, and benzoyl peroxide acetate.

[0015] Preferably, in step (2), the ratio of the dispersant to the conductive nanoparticles is 1:1 to 1:4.

[0016] Preferably, in step (3), the conductive nanoparticles account for 1% to 7% of the total content; further preferably, the conductive nanoparticles account for 2% to 4% of the total content.

[0017] Preferably, in step (3), the content of the free radical thermal curing agent accounts for 1% to 2% of the total content.

[0018] The method for preparing a flexible sensor with adjustable sensitivity over a wide range provided by the present invention has the following beneficial effects:

[0019] 1. Shape memory materials can be fixed at low temperatures and recovered at high temperatures at different elongations, so that the sensitivity of the sensor can be different at different fixed lengths, and the sensitivity can be restored to the initial sensitivity at high temperatures, thus achieving reversible and adjustable sensitivity. Figure 6 As shown in the figure on the right, the initial sensitivity of the sensor with 2% CB addition is 2.61, and the sensitivity when the fixed length is 200% is 231.74. The sensitivity range of the fixed length can be adjusted by shape memory to 2.61 to 231.74.

[0020] 2. The preparation process of the present invention is simple and low in cost.

[0021] 3. The shape memory resin-based flexible sensor composite material prepared by the present invention can be customized in shape and size according to needs. Therefore, when preparing flexible sensors, it has the advantages of high flexibility, strong applicability, and easy array manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The manufacturing flow chart of the flexible sensor composite material prepared by the present invention;

[0023] Figure 2 A sample diagram of the flexible sensor composite material prepared by the present invention;

[0024] Figure 3 This is a SEM image of the flexible sensor composite material prepared by the present invention;

[0025] Figure 4 This is a shape memory performance diagram of the flexible sensor composite material prepared by the present invention;

[0026] Figure 5 A schematic diagram of the shape memory of the flexible sensor composite material prepared by the present invention after being stretched to a fixed length, and testing the sensitivity at the fixed length;

[0027] Figure 6 This is a sensing performance diagram of the flexible sensor composite material prepared by the present invention; the left figure is a sensitivity adjustment performance diagram when using different dispersants, and the right figure is a sensitivity adjustment performance diagram when using different carbon black contents. DETAILED DESCRIPTION

[0028] In order to illustrate the effects of the present invention, the present invention is further described in detail with reference to examples, but the present invention is not limited to these examples.

[0029] Example 1

[0030] The method of this example of shape memory resin-based flexible sensor material is as follows:

[0031] (1) 1.5 g of polycaprolactone, 1.2 g of polyurethane acrylic resin, and 4.8 g of butyl acrylate were mechanically stirred in an oil bath at 60 °C for 2 h;

[0032] (2) 25 mg of carbon black (CB) and 45 mg of nonylphenol polyoxyethylene ether-10 were mixed by grinding, and the mixed powder was added to (1), and mechanically stirred for 12 h under heating in an oil bath at 65° C.;

[0033] (3) The stirred solution was vacuum-evacuated in a vacuum oven at 65°C for 20 min;

[0034] (4) Add 60 mg of benzoyl peroxide to the vacuum-evacuated sample and stir at room temperature for 2 min;

[0035] (5) Pour the sample stirred in (4) into a mold, place it in an oven and cure it at 80°C for 12 h, then heat it to 130°C and cure it for 24 h.

[0036] Example 2

[0037] The method of this example of shape memory resin-based flexible sensor material is as follows:

[0038] (1) 1.5 g of polycaprolactone, 1.2 g of polyurethane acrylic resin, and 4.8 g of butyl acrylate were mechanically stirred in an oil bath at 60 °C for 2 h;

[0039] (2) 120 mg of carbon black and 150 mg of nonylphenol polyoxyethylene ether-10 were mixed by grinding, and the mixed powder was added to (1), and mechanically stirred for 12 h under heating in an oil bath at 65° C.;

[0040] (3) The stirred solution was vacuum-evacuated in a vacuum oven at 65°C for 20 min;

[0041] (4) Add 60 mg of benzoyl peroxide to the vacuum-evacuated sample and stir at room temperature for 20 min;

[0042] (5) Pour the sample stirred in (4) into a mold, place it in an oven and cure it at 80°C for 12 hours, then heat it to 120°C and cure it for 24 hours.

[0043] Example 3

[0044] The method of this example of shape memory resin-based flexible sensor material is as follows:

[0045] (1) 1.5 g of polycaprolactone, 1.2 g of polyurethane acrylic resin, and 4.8 g of butyl acrylate were mechanically stirred in an oil bath at 60 °C for 2 h;

[0046] (2) 225 mg of carbon black and 225 mg of nonylphenol polyoxyethylene ether-10 were mixed by grinding, and the mixed powder was added to (1), and mechanically stirred for 12 h under heating in an oil bath at 60° C.;

[0047] (3) The stirred solution was vacuum-evacuated in a vacuum oven at 60°C for 20 min;

[0048] (4) Add 60 mg of benzoyl peroxide to the vacuum-evacuated sample and stir at room temperature for 20 min;

[0049] (5) Pour the sample stirred in (4) into a mold, place it in an oven and cure it at 80°C for 12 hours, then heat it to 120°C and cure it for 24 hours.

[0050] Example 4

[0051] The method of this example of shape memory resin-based flexible sensor material is as follows:

[0052] (1) 1.5 g of polycaprolactone, 1.2 g of polyurethane acrylic resin, and 4.8 g of butyl acrylate were mechanically stirred in an oil bath at 60 °C for 2 h;

[0053] (2) 150 mg of carbon black and 225 mg of nonylphenol polyoxyethylene ether-10 were mixed by grinding, and the mixed powder was added to (1), and mechanically stirred for 12 h under heating in an oil bath at 60° C.;

[0054] (3) The stirred solution was vacuum-evacuated in a vacuum oven at 60°C for 20 min;

[0055] (4) Add 60 mg of benzoyl peroxide to the vacuum-evacuated sample and stir at room temperature for 20 min;

[0056] (5) Pour the sample stirred in (4) into a mold, place it in an oven and cure it at 80°C for 12 hours, then heat it to 120°C and cure it for 24 hours.

[0057] Example 5

[0058] The method of this example of shape memory resin-based flexible sensor material is as follows:

[0059] (1) 1.5 g of polycaprolactone, 1.2 g of polyurethane acrylic resin, and 4.8 g of butyl acrylate were mechanically stirred in an oil bath at 60 °C for 2 h;

[0060] (2) 150 mg of carbon black and 150 mg of polyoxyethylene dodecanol ether were mixed by grinding, and the mixed powder was added to (1), and mechanically stirred for 12 h under heating in an oil bath at 60° C.;

[0061] (3) The stirred solution was vacuum-evacuated in a vacuum oven at 60°C for 20 min;

[0062] (4) Add 60 mg of benzoyl peroxide to the vacuum-evacuated sample and stir at room temperature for 20 min;

[0063] (5) Pour the sample stirred in (4) into a mold, place it in an oven and cure it at 80°C for 12 hours, then heat it to 120°C and cure it for 24 hours.

Claims

1. A method for preparing a flexible sensor with adjustable sensitivity over a wide range. It is characterized in that The following steps are involved: Step (1): preparing a shape memory material matrix; Step (2): grinding and mixing the conductive nanoparticles and the dispersant; Step (3): adding the conductive nanoparticles mixed in step (2) into the shape memory material matrix and mixing them thoroughly to obtain a shape memory matrix containing conductive nanoparticles; Step (4): vacuum defoaming and thermally polymerizing the shape memory matrix containing the conductive nanoparticles to obtain a shape memory resin-based sensor.

2. The method for preparing a shape memory resin-based sensor with adjustable sensitivity in a wide range according to claim 1, Features: The shape memory resin includes two parts: a matrix and a crystalline phase. The matrix includes one or more of a polyurethane shape memory resin, a polypropylene shape memory resin, a polyethylene shape memory resin, a polyester shape memory resin, and a silicone shape memory rubber; the crystalline phase polymer includes one or more of a polyester (such as polycaprolactone, polyvalerolactone, etc.) and a polyether (such as polytetrahydrofuran, polyethylene oxide).

3. The method for preparing a flexible sensor with adjustable sensitivity in a wide range according to claim 1, Features: The conductive nanoparticles include one of carbon black, carbon nanotubes, graphene, graphene oxide or a mixture thereof.

4. The method for preparing a flexible sensor with adjustable sensitivity over a wide range according to claim 1, Features: The dispersant is one or more of octanol polyoxyethylene ether, dodecanol polyoxyethylene ether, nonylbenzene polyoxyethylene ether, octanol polyoxyethylene ether sodium sulfate, and nonyl polyoxyethylene ether.

5. The method for preparing a flexible sensor with adjustable sensitivity in a wide range according to claim 1, Features: The curing agent is one or more of benzoyl peroxide, benzoyl peroxide propionic acid, benzoyl peroxide butyric acid, and benzoyl peroxide acetate.

6. The method for preparing a flexible sensor with adjustable sensitivity in a wide range according to claim 1, Features: The curing agents are all free radical thermal curing agents.

7. The method for preparing a flexible sensor with adjustable sensitivity in a wide range according to claim 1, Features: The mixing process of the conductive nanoparticles and the shape memory matrix described in step (3) needs to be achieved by mechanical stirring at 60° C.-80° C. for 10 h to 15 h.

8. The method for preparing a flexible sensor with adjustable sensitivity over a wide range according to claim 1, Features: The thermal curing process described in step (4) is to pre-polymerize at 60°C to 80°C for 10h to 15h, and then heat to 120°C for polymerization for 20h to 24h.

Images