WO2019218553A1

WO2019218553A1 - Flexible temperature sensor and preparation method therefor

Info

Publication number: WO2019218553A1
Application number: PCT/CN2018/105599
Authority: WO
Inventors: 涂大记; 夏厚君; 潘华; 杨晓明
Original assignee: 浙江欧仁新材料有限公司
Priority date: 2018-05-17
Filing date: 2018-09-14
Publication date: 2019-11-21
Also published as: CN108955928B; CN108955928A

Abstract

A flexible temperature sensor and a preparation method therefor. The flexible temperature sensor comprises a sensor body and electrodes. The sensor body comprises a first TPU film insulating layer, a first conducting layer, an isolating layer, a second conducting layer, and a second TPU film insulating layer from top to bottom. The electrodes are led out from the first conducting layer or the second conducting layer, and are connected to an external circuit. The isolating layer is a mixture of a semi-crystalline polymer and nanometer silver wires, and the conductive/resistance performance of the isolating layer changes with temperature. Since the isolating layer is a semi-crystalline polymer, the ratio of crystallization to non-crystallization of the semi-crystalline polymer is different at different temperature, and thus, the resistance between the two electrodes changes. High sensitivity is achieved, since large resistance change occurs under small change in temperature. Data is processed by means of a computer according to the association relationship between temperature and resistance, so as to detect the temperature change.

Description

Flexible temperature sensor and preparation method thereof

Technical field

The invention relates to a sensor, in particular to a flexible temperature sensor and a preparation method thereof.

Background technique

Conventional temperature sensors are used as special devices for collecting temperature data of control points. A wide variety of commonly used temperature sensors are available. The ideal temperature sensor should be characterized by low cost, simple preparation and versatility. The resistance type temperature sensor has good flexibility, simple structure, good compatibility, and easy change of resistance change, and is often applied to electronic skin. The principle of the resistive temperature sensor is that the resistance of the material changes with temperature, and the sensor material is mostly metal such as gold and platinum. Platinum as a temperature sensor can achieve an accuracy of 0.03 ° C under a large temperature range. For flexible temperature sensors, conductive polymers, composite conductive polymer materials, etc. are common, but their sensitivity is low, and it is not suitable for temperature monitoring in the human temperature range. Recently, conductive filler-filled polymers have received wide attention. Due to the different coefficients of thermal expansion of the matrix material and the conductive filler, the resistance change of the conductive filler-filled polymer is many orders of magnitude higher than that of the conventional temperature sensor when the crystalline polymer reaches the melting point. Controlling the polymerization strength By setting the melting point of the crystalline polymer near the human body temperature, it can overcome the shortcomings of the low sensitivity of the conventional flexible temperature sensitive material. In addition, since the morphology of the matrix material melts and condenses near the melting point and the condensation point, the polymer using the separate matrix and filler tends to have little reproducibility of resistance change and low repeatability. When the polymer is used in combination with a plurality of matrix materials and/or a plurality of conductive fillers, the repeatability and reproducibility are improved.

Summary of the invention

In order to solve the above problems, the present invention provides a flexible temperature sensor and a method of fabricating the same.

The flexible temperature sensor provided by the present invention includes a sensor body and an electrode; the sensor body includes a first TPU thin film insulating layer, a first conductive layer, an isolation layer, a second conductive layer, and a second TPU thin film insulating layer from top to bottom. The electrode is taken out from the first conductive layer or the second conductive layer and connected to an external circuit; the isolation layer is a mixture of a semi-crystalline polymer and a nano-silver wire. The so-called semi-crystalline polymer, that is, the internal structure of the polymer, is a crystalline structure mixed with an amorphous structure, the crystal structure is a non-conductor, and the amorphous structure is a conductor. At different temperatures, the ratio of crystalline to non-crystalline of the semi-crystalline polymer is different, so the electrical resistance also changes. However, if there is only a semi-crystalline polymer, the sensitivity is not high, and adding a small amount of nano-silver wire can greatly enhance the sensitivity of the isolation layer, so that a small change in temperature can be easily sensed.

Preferably, the semi-crystalline polymer is polyethylene oxide, and the separator has a thickness of 400-600 μm.

Preferably, the polyethylene oxide has a molecular weight of 40*10 ⁴ -60*10 ⁴ . Polyoxyethylene has the highest sensitivity to temperature in both crystalline and amorphous states of this molecular weight.

In the separator, the nano silver wire accounts for 0.3-0.5% by weight of the semi-crystalline polymer. The addition of nano-silver lines greatly amplifies the sensitivity of the isolation layer, but if it is added too much, it will also affect the external environment.

Preferably, the first conductive layer and the second conductive layer are silver nanowire films.

Preferably, the silver nanowire film is dried by a solution of 0.3 to 1.5 wt% of a silver nanowire isopropanol, and has a thickness of 80 to 180 nm. This ratio is advantageous for slit coating.

Preferably, the first TPU film insulating layer and the second TPU film insulating layer have a thickness of 4.5-120 μm.

The nanosilver wire has a diameter of 20-150 nm.

The preparation method of the above flexible temperature sensor comprises the following steps:

S1, the semi-crystalline polymer is heated to a molten state, and the nano-silver wire is added and stirred uniformly, and the temperature is lowered to 30-50 ° C, and pressed into a film of 400-600 μm to serve as a separator;

S2, the nano-conductive material is slit-coated on the front surface of the isolation layer in step S1, and after drying, a first conductive layer is formed; and a Slot-Die coater can be used.

S3, slit-coating 120-130 ° C TPU hot melt adhesive on the other side of the first conductive layer in step S2, cooling to room temperature to form a first TPU thin film insulating layer;

S4, slit coating the nano conductive material solution on the reverse side of the isolation layer in step S1, after drying, forming a second conductive layer;

S5, the second surface of the second conductive layer in step S4 is slot-coated with a TPU hot melt adhesive at 120-130 ° C, and cooled to room temperature to form a second TPU thin film insulating layer;

S6. Leading a pair of electrodes on the conductive material of the first conductive layer and the second conductive layer, and performing curing and packaging according to the required sensing range.

Preferably, the semi-crystalline polymer in step S1 is polyethylene oxide, and the temperature in the molten state is 120-130 °C.

Preferably, the drying method in steps S2 and S4 is wind drying.

Preferably, in the step S6, the curing package adopts a method of dispensing a UV curing resin.

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

1. The separator in the process of the present invention is a semi-crystalline polymer. At different temperatures, the ratio of crystallization to non-crystallization of the semi-crystalline polymer is different, so that the electrical resistance between the two electrodes changes. In combination with the addition of a small amount of nanometer, the sensitivity is high and there is a slight temperature change, which is enough to have a large resistance change, thereby detecting the temperature change.

2. The structure of the present invention can be flexibly applied to industries such as wearable and electronic skin.

3. The invention can realize the different sensitivity and range requirements of different sensors by adjusting the different semi-crystalline polymers of the isolation layer, the shape of the isolation layer, and the square resistance of the two layers of electrodes.

4. Dimethylsiloxane is difficult to photocurable. The novel photoinitiator is innovatively used in the present invention, so that the photocuring time of the PDMS encapsulation layer can meet the requirements.

5. The preparation method of the temperature sensor of the invention combines high-precision roll-to-roll coating technology and rapid UV-curing lamination reaction technology to realize flexible transparent conductive with good flexibility, stretchability, high light transmittance and excellent electrical conductivity. Electrode industrialization.

Detailed ways

The following is a detailed description of the present invention, but the following is merely a further explanation of the present invention, and is not intended to limit the scope of the present invention. The scope of protection of the invention.

Example 1

The nano-conductive material solution is a 0.3 to 1.5 wt% silver nanowire isopropanol solution.

S1, heating the polyoxyethylene particles having a molecular weight of 40-60*10 ⁴ to a molten state, adding a nano silver wire and stirring uniformly, cooling to 30-50 ° C, and pressing into a film of 400-600 μm as a separation layer; The silver wire accounts for 0.3-0.5% by weight of the ethylene oxide film.

S2. The nano-conductive material solution is slit-coated with a Slot-Die coater on the front surface of the separator in step S1, and dried to a thickness of 80 to 180 nm. First conductive layer;

S3, the other side of the first conductive layer of step S1 is slot-coated with a TPU hot melt adhesive of 120-130 ° C by a Slot-Die coater, and cooled to room temperature to form a first TPU thin film insulating layer;

S4, the reverse conductive surface of the step S1 is coated with a nano-conductive material solution by slot coating with a Slot-Die coater, and after air drying, a second conductive layer having a thickness of 80-180 nm is formed;

S5, in the other side of the second conductive layer of step S4, slot-coating 120-130 ° C TPU hot melt adhesive with a Slot-Die coater, cooling to room temperature to form a second TPU thin film insulating layer;

The isolation layer is a polyethylene oxide film combined with a nano silver wire. At different temperatures, the ratio of crystallization to non-crystallization of the polyethylene oxide film is different, thus changing the electrical resistance between the two electrodes. Achieving high sensitivity and a small temperature change is enough to have a large resistance change to detect temperature changes.

Comparative example 1

S1, the polyoxyethylene particles having a molecular weight of 40-60*10 ⁴ are heated to a molten state, cooled to 30-50 ° C, and pressed into a film of 400-600 μm to serve as a separator;

S2. The nano conductive material solution is slit-coated on the front surface of the isolation layer in step S1 by a Slot-Die coater, and dried to a thickness of 80 to 180 nm. First conductive layer;

The isolation layer is a polyethylene oxide film at different temperatures, thus causing a slight change in resistance between the two electrodes, but the sensitivity is not high and the temperature change cannot be accurately detected.

Claims

A flexible temperature sensor, comprising: a sensor body and an electrode; the sensor body comprises a first TPU film insulating layer, a first conductive layer, an isolation layer, a second conductive layer, from top to bottom, a second TPU thin film insulating layer; the electrode is taken out from the first conductive layer or the second conductive layer and connected to an external circuit; the isolating layer is a mixture of a semi-crystalline polymer and a nano silver wire.
The flexible temperature sensor according to claim 1, wherein said semi-crystalline polymer is polyethylene oxide having a molecular weight of 40*104-60*104 and said separator has a thickness of 400-600 μm.
The flexible temperature sensor according to claim 2, wherein in the isolating layer, the nano silver wire accounts for 0.3-0.5% by weight of the semi-crystalline polymer.
The flexible temperature sensor according to claim 1, wherein the first conductive layer and the second conductive layer are silver nanowire films, and the silver nanowire film is 0.3 to 1.5 wt% of silver nanowires. The alcohol solution is dried and has a thickness of 80 to 180 nm.
The flexible temperature sensor according to claim 1, wherein the first TPU film insulating layer and the second TPU film insulating layer have a thickness of 4.5 to 120 μm.
The flexible temperature sensor of claim 1 wherein said nanosilver wire has a diameter of from 20 to 150 nm.
The method of manufacturing a flexible temperature sensor according to claim 1, comprising the steps of:

S1, the semi-crystalline polymer is heated to a molten state, and the nano-silver wire is added and stirred uniformly, and the temperature is lowered to 30-50 ° C, and pressed into a film of 400-600 μm to serve as a separator;

S2, slit coating the nano conductive material solution on the front surface of the isolation layer in step S1, after drying, forming a first conductive layer;

S3, slit-coating 120-130 ° C TPU hot melt adhesive on the other side of the first conductive layer in step S2, cooling to room temperature to form a first TPU thin film insulating layer;

S4, slit coating the nano conductive material solution on the reverse side of the isolation layer in step S1, after drying, forming a second conductive layer;

S5, the second surface of the second conductive layer in step S4 is slot-coated with a TPU hot melt adhesive at 120-130 ° C, and cooled to room temperature to form a second TPU thin film insulating layer;

S6. Leading a pair of electrodes on the conductive material of the first conductive layer and the second conductive layer, and performing curing and packaging according to the required sensing range.
The production method according to claim 7, wherein the semi-crystalline polymer in the step S1 is polyethylene oxide, and the temperature in the molten state is from 120 to 130 °C.
The preparation method according to claim 7, wherein the drying method in steps S2 and S4 is wind drying.
The preparation method according to claim 7, wherein the step of curing the package in the step S6 is a method of dispensing a UV curable resin.