Method for preparing flexible self-driven temperature / pressure sensor using thermoelectric gel

Abstract

The invention provides a method for preparing a flexible self-driven temperature / pressure sensor by using thermoelectric gel, and belongs to the technical field of gel thermoelectric device preparation methods. The technical problem to be solved is to provide an improvement of the method for preparing a flexible self-driven temperature / pressure sensor by using thermoelectric gel. The technical scheme adopted to solve the above technical problem is as follows: a) preparing a solution with a concentration of 0.1 mol / L-0.3 mol / L and a stoichiometric ratio of 1:1 of sulfate and sulfite, adding 5-10 g of polyvinyl alcohol and 0.1-0.2 g of polystyrene sulfonate to the solution, and stirring at a constant temperature of 70-100 DEG C for 2-4 hours; b) after the reaction is completed, pouring the solution into a mold with conductive fibers placed at both ends, placing it in a mold at-20 DEG C and freezing it for 24-48 hours to obtain a sulfate / sulfite water gel; c) encapsulating the gel prepared in step b, and extracting electrodes from the conductive fibers to obtain a gel thermoelectric device and a self-driven temperature / pressure sensor; the invention is applied to the preparation of the gel thermoelectric device.

Description

Technical Field

[0001] The present invention belongs to the field of electronic information technology and specifically relates to a conductive ion salt Na 2 SO 4 、Na 2 SO 3 A gel thermoelectric device, in particular a device using redox reaction of SO 4 2- / SO 3 2- Methods for preparing flexible and stretchable gel thermoelectric devices and self-driven temperature / pressure sensors. Background Art

[0002] Thermoelectric batteries are devices that use the temperature difference between the two ends of the device to continuously convert heat energy into electrical energy. They have attracted more and more attention because they can continuously convert heat into electrical energy without producing byproducts or consuming materials. Traditional thermoelectric batteries based on the semiconductor Seebeck effect have poor environmental adaptability and limited application range due to their low Seebeck coefficient, rigidity and inflexibility. For the recycling of low-grade waste heat in the environment, although the use of organic semiconductors for thermoelectric conversion is one of the feasible paths, the inherent physical and chemical instability and low mobility of organic semiconductors also seriously restrict their application development. However, based on the oxidation / reduction reaction of the redox couple at the hot and cold ends and the convection and diffusion of the electrolyte to the corresponding electrodes, a potential difference can be generated at the two ends of the thermoelectric battery, thereby continuously generating electrical energy without consuming any materials. Hydrogel is a new type of electrolyte that organically combines a hydrophilic matrix and a conductive medium. It has high flexibility, stretchability, and stable physical and chemical properties. It has broad application prospects in the fields of flexible electronic devices. Therefore, by dissolving the redox couple ion salt in the hydrogel and combining the high ionic conductivity, stretchability and tissue softness of the hydrogel, a flexible and stretchable high-efficiency gel thermoelectric device can be obtained. 6 3- / Fe(CN) 6 4- ,I - / I 3- , Fe 3+ / Fe 2+ etc., which are basically toxic or corrosive, and for the use of SO 4 2- / SO 3 2- There is no report on the preparation of gel thermoelectric devices. In addition, it is also very meaningful to develop a self-driven multifunctional sensor based on gel thermoelectric devices to realize passive real-time monitoring of various environmental parameters. Summary of the invention

[0003] In order to overcome the deficiencies in the prior art, the present invention aims to solve the technical problem of providing an improved method for preparing a flexible self-driven temperature / pressure sensor using thermoelectric gel.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing a flexible self-driven temperature / pressure sensor using thermoelectric gel, comprising the following steps:

[0005] a) preparing a solution with a concentration of 0.1 mol / L-0.3 mol / L and a stoichiometric ratio of 1:1 between sulfate and sulfite, adding 5-10 g of polyvinyl alcohol and 0.1-0.2 g of PEDOT:PSS to the solution, and stirring at a constant temperature of 70-100°C for 2-4 hours;

[0006] b) After the reaction is completed, the solution is poured into a mold with conductive fibers placed at both ends, and frozen at -20°C for 24-48 hours to obtain a sulfate / sulfite gel;

[0007] c) Encapsulating the gel prepared in step b, and extracting electrodes from the conductive fibers, thereby obtaining a gel thermoelectric device and a self-driven temperature / pressure sensor.

[0008] The sulfate and sulfite used in step a) are specifically sodium sulfate and sodium sulfite or potassium sulfate and potassium sulfite.

[0009] In the step a), the mass fractions of PEDOT and PSS in PEDOT:PSS are 0.5wt% and 0.8wt% respectively, and the conductivity is 1S / cm.

[0010] The solvent in the solution prepared in step a) is an aqueous solution with a mass concentration of 10% dimethyl sulfoxide.

[0011] In the step a), stirring is performed at a constant temperature of 90-100° C. for 2-4 hours.

[0012] The step b) is to pre-fix the two conductive fibers in the mold.

[0013] The step c) is to encapsulate the entire gel device by casting with Ecoflex at one time.

[0014] The Seebeck coefficient of the gel thermoelectric device exceeds 1.6 mV / K.

[0015] The self-driven temperature / pressure sensor is flexible and stretchable, and can passively detect changes in ambient temperature and pressure.

[0016] The beneficial effects of the present invention relative to the prior art are as follows: the present invention uses conductive ion salts to prepare gel thermoelectric devices, and only needs to use cheap and simple raw materials at a low temperature of 90-100°C: sodium sulfate, sodium sulfite, polystyrene sulfonate, polyvinyl alcohol, dimethyl sulfoxide, water, etc. for synthesis, that is, after the reaction solvent is evenly mixed, the raw materials are added to the reaction solvent and placed in a magnetic stirrer for heating and stirring. The operation procedure is simple, the parameters to be controlled during the synthesis process are relatively few, and the synthesis cost is low. The prepared sodium sulfate / sodium sulfite hydrogel has excellent softness, stretchability, conductivity, etc. In addition, the hydrogel device not only exhibits excellent thermoelectric output performance, with a Seebeck coefficient exceeding 1.6mV / K, but also has a high sensitivity response to changes in ambient temperature and pressure, and the output voltage has a good linear relationship with temperature and pressure, which indicates that the prepared hydrogel device can not only collect low-grade thermal energy from the environment, but also be used for self-driven monitoring of ambient temperature and pressure changes (without external power supply). BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be further described below in conjunction with the accompanying drawings.

[0018] Figure 1 It is the steady-state voltage and output power of the gel thermoelectric device prepared by the method of the present invention at a temperature difference of 10°C.

[0019] Figure 2 It is the conductivity of the gel prepared by the method of the present invention at different concentration ratios.

[0020] Figure 3 It is the tensile strain curve of the gel prepared by the method of the present invention.

[0021] Figure 4 These are photographs of the actual gel prepared by the method of the present invention being bent, twisted and stretched.

[0022] Figure 5 It is the voltage output of the gel thermoelectric device prepared by the method of the present invention under different temperature differences.

[0023] Figure 6 It is the voltage curve of the gel thermoelectric device prepared by the method of the present invention under a temperature difference of 5°C.

[0024] Figure 7 It is the current output of the gel thermoelectric device prepared by the method of the present invention under different compressive stresses.

[0025] Figure 8 The present invention is a current curve of the gel thermoelectric device prepared by the method of the present invention under an external force of about 200 mN at a temperature difference of 5°C. DETAILED DESCRIPTION

[0026] like Figure 1-8As shown, the present invention studies and explores a method based on redox electrochemical reaction of SO 4 2- / SO 3 2 Flexible stretchable gel electrolyte, aiming to provide a SO-based 4 2- / SO 3 2- Flexible and stretchable gel thermoelectric device and its self-driven temperature / pressure sensor preparation method.

[0027] To achieve the above purpose, the technical solution adopted by the present invention is: a method based on redox reaction of SO 4 2- / SO 3 2- The preparation method of the flexible stretchable gel thermoelectric device and the self-driven temperature / pressure sensor includes the following steps.

[0028] a) Prepare a 0.1 mol / L-0.3 mol / L sulfate and sulfite solution (stoichiometric ratio is 1:1) (the solvent is a 10% aqueous solution of dimethyl sulfoxide), add 5-10 g polyvinyl alcohol and 0.1-0.2 g PEDOT:PSS to the solution, and stir at a constant temperature of 90-100°C for 2-4 hours;

[0029] b) After the reaction is completed, the solution is poured into a mold with conductive fibers placed at both ends, and frozen at -20°C for 24-48 hours to obtain a sulfate / sulfite gel;

[0030] c) The gel prepared in step b is encapsulated with Ecoflex, and electrodes are led out from the conductive fibers to obtain a gel thermoelectric device and a self-driven temperature / pressure sensor.

[0031] Preferably, the redox couple SO 4 2- / SO 3 2- Provided for sulfate and sulfite, it can be sodium sulfate and sodium sulfite, potassium sulfate and potassium sulfite, etc.

[0032] Preferably, the mass fractions of PEDOT and PSS are 0.5wt% and 0.8wt% respectively, and the conductivity is 1S / cm.

[0033] Preferably, the step b is to pre-fix the two conductive fibers in the mold.

[0034] Preferably, in step c, the entire gel device is encapsulated by pouring Ecoflex (10:1) at one time.

[0035] Preferably, the Seebeck coefficient of the gel thermoelectric device exceeds 1.6 mV / K.

[0036] Preferably, the self-driven temperature / pressure sensor is capable of passively detecting changes in ambient temperature and applied pressure simultaneously.

[0037] The technical solution of the present invention is described in detail below in conjunction with embodiments.

[0038] Example 1

[0039] The specific steps are as follows:

[0040] Step 1, prepare a 0.1 mol / L sulfate and sulfite solution (stoichiometric ratio is 1:1) (the solvent is a 10% aqueous solution of dimethyl sulfoxide), add 5 g polyvinyl alcohol and 0.1 g PEDOT:PSS to the solution, and stir at a constant temperature of 70-80°C for 2-4 hours;

[0041] Step 2: After the reaction is completed, the solution is poured into a mold with conductive fibers placed at both ends, and frozen at -20°C for 24-48 hours to obtain a sodium sulfate / sodium sulfite hydrogel;

[0042] Step 3: Encapsulate the gel prepared in step 2 with Ecoflex, and lead electrodes from the conductive fibers to obtain a gel thermoelectric device and a self-driven temperature / pressure sensor.

[0043] Example 2

[0044] The specific steps are as follows:

[0045] Step 1, prepare a 0.2 mol / L sulfate and sulfite solution (stoichiometric ratio is 1:1) (the solvent is a 10% aqueous solution of dimethyl sulfoxide), add 7.5 g polyvinyl alcohol and 0.15 g PEDOT:PSS to the solution, and stir at a constant temperature of 90-100°C for 2-4 hours;

[0046] Step 2: After the reaction is completed, the solution is poured into a mold with conductive fibers placed at both ends, and frozen at -20°C for 24-48 hours to obtain a sodium sulfate / sodium sulfite hydrogel;

[0047] Step 3: Encapsulate the gel prepared in step 2 with Ecoflex, and lead electrodes from the conductive fibers to obtain a gel thermoelectric device and a self-driven temperature / pressure sensor.

[0048] Example 3

[0049] The specific steps are as follows:

[0050] Step 1, prepare a 0.3 mol / L sulfate and sulfite solution (stoichiometric ratio is 1:1) (the solvent is a 10% aqueous solution of dimethyl sulfoxide), add 10 g polyvinyl alcohol and 0.2 g PEDOT:PSS to the solution, and stir at a constant temperature of 90-100°C for 2-4 hours;

[0051] Step 2: After the reaction is completed, the solution is poured into a mold with conductive fibers placed at both ends, and frozen at -20°C for 24-48 hours to obtain a sodium sulfate / sodium sulfite hydrogel;

[0052] Step 3: Encapsulate the gel prepared in step 2 with Ecoflex, and lead electrodes from the conductive fibers to obtain a gel thermoelectric device and a self-driven temperature / pressure sensor.

[0053] like Figure 1 The steady-state voltage and output power of the gel thermoelectric device under a temperature difference of 10°C are given. The greater the temperature difference, the greater the output power. Figure 2 The conductivity given shows that the experimentally prepared gel has high conductivity; Figure 3 The tensile stress-strain diagrams presented show that the mechanical properties of the gels after addition of sulfate and sulfite can be tuned over a wide range; Figure 4 The physical pictures given show that the hydrogel can be changed into different shapes at will, which can improve the utilization efficiency when used; Figure 5 This indicates that the hydrogel is highly sensitive to temperature and exhibits different voltage outputs as the temperature changes, so it can be used in temperature sensing. Figure 5 It also shows that the hydrogel has a high Seebeck coefficient of about 1.631 mV / K; Figure 6 The voltage cycle curve shows that the temperature difference is repeatedly applied within 60s; Figure 7 It shows that when different pressures are applied to the hydrogel, the current output of the hydrogel will change to different degrees, which can be used for pressure sensing. Figure 8 It shows the current change curve of external force application-release under 5℃ temperature difference.

[0054] What needs to be explained about the specific structure of the present invention is that the connection relationship between the various component modules adopted in the present invention is definite and feasible. Except for the special instructions in the embodiments, the specific connection relationship can bring about the corresponding technical effects, and solve the technical problems raised by the present invention without relying on the execution of the corresponding software program. Except for the specific instructions, the models and connection methods of the components, modules and specific components appearing in the present invention belong to the existing technologies such as published patents, published journal articles, or common knowledge that can be obtained by technical personnel in this field before the application date, and there is no need to elaborate, so that the technical solution provided in this case is clear, complete and feasible, and the corresponding physical products can be reproduced or obtained according to the technical means.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a flexible self-driven temperature / pressure sensor using thermoelectric gel, characterized in that: The steps include: a) preparing a solution with a concentration of 0.1 mol / L-0.3 mol / L and a stoichiometric ratio of 1:1 between sulfate and sulfite, adding 5-10 g of polyvinyl alcohol and 0.1-0.2 g of PEDOT:PSS to the solution, and stirring at a constant temperature of 70-100°C for 2-4 hours; b) After the reaction is completed, the solution is poured into a mold with conductive fibers placed at both ends, and frozen at -20°C for 24-48 hours to obtain a sulfate / sulfite gel; c) Encapsulating the gel prepared in step b, and extracting electrodes from the conductive fibers, thereby obtaining a gel thermoelectric device and a self-driven temperature / pressure sensor.

2. The method for preparing a flexible self-driven temperature / pressure sensor using thermoelectric gel according to claim 1, characterized in that: The sulfate and sulfite used in step a) are specifically sodium sulfate and sodium sulfite or potassium sulfate and potassium sulfite.

3. The method for preparing a flexible self-driven temperature / pressure sensor using thermoelectric gel according to claim 1, characterized in that: In the step a), the mass fractions of PEDOT and PSS in PEDOT:PSS are 0.5wt% and 0.8wt% respectively, and the conductivity is 1S / cm.

4. The method for preparing a flexible self-driven temperature / pressure sensor using thermoelectric gel according to claim 1, characterized in that: The solvent in the solution prepared in step a) is an aqueous solution with a mass concentration of 10% dimethyl sulfoxide.

5. The method for preparing a flexible self-driven temperature / pressure sensor using thermoelectric gel according to claim 1, characterized in that: In the step a), stirring is performed at a constant temperature of 90-100° C. for 2-4 hours.

6. The method for preparing a flexible self-driven temperature / pressure sensor using thermoelectric gel according to claim 1, characterized in that: The step b) is to pre-fix the two conductive fibers in the mold.

7. The method for preparing a flexible self-driven temperature / pressure sensor using thermoelectric gel according to claim 1, characterized in that: The step c) is to encapsulate the entire gel device by casting with Ecoflex at one time.

8. The method for preparing a flexible self-driven temperature / pressure sensor using thermoelectric gel according to claim 1, characterized in that: The Seebeck coefficient of the gel thermoelectric device exceeds 1.6 mV / K.

9. The method for preparing a flexible self-driven temperature / pressure sensor using thermoelectric gel according to claim 1, characterized in that: The self-driven temperature / pressure sensor is flexible and stretchable, and can passively detect changes in ambient temperature and pressure.

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