A flexible asymmetric ionic gel and temperature sensor with directional voltage output in response to temperature

Abstract

This application discloses a flexible asymmetric ionic gel and a temperature sensor that provide directional voltage output in response to temperature. The flexible asymmetric ionic gel comprises an n-type ionic gel and a p-type ionic gel, which are chemically bonded. The n-type ionic gel is obtained by polymerization using an n-type prepolymer, and the p-type ionic gel is obtained by polymerization using a p-type prepolymer. The n-type prepolymer comprises 2,2,2-trifluoroethyl acrylate, 1-ethyl-3-methylimidazoline bis(trifluoromethanesulfonyl)imide, a crosslinking agent, and an initiator. The p-type prepolymer comprises 2,2,2-trifluoroethyl acrylate, 1-ethyl-3-methylimidazoline bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylimidazolium chloride, a crosslinking agent, and an initiator. The flexible asymmetric ionic gel provided by this application combines high thermal power, directional voltage output, temperature responsiveness, and mechanical flexibility.

Description

Technical Field

[0001] This application relates to the field of thermoelectric materials technology, and in particular to a flexible asymmetric ionic gel and temperature sensor that outputs a directional voltage in response to temperature. Background Technology

[0002] Thermoelectric materials can directly convert heat energy into electrical energy and have been widely used in waste heat recovery, temperature detection, and other fields. Thermal power is a direct indicator for evaluating the performance of thermoelectric materials, and is generally quantified using the Seebeck coefficient. Ionic thermoelectric materials have achieved rapid development due to their Seebeck coefficients, which are several orders of magnitude higher than those of electronic thermoelectric materials. The Seebeck coefficient of ionic thermoelectric materials is defined as the ratio of voltage to temperature difference (S= V / T); Generally, the potential generated by the thermal migration of cations is defined as positive (i.e., p-type), while that generated by the migration of anions is defined as negative (i.e., n-type).

[0003] To improve the performance and efficiency of ion thermoelectric materials, researchers have focused on two main areas: optimizing material morphology and enhancing thermal power. In terms of morphology, materials have evolved from liquid states (such as aqueous solutions and organic solutions) that are difficult to encapsulate to quasi-solid states (such as hydrogels and ion gels). Quasi-solid states significantly improve the processability and safety of thermoelectric devices. Regarding enhancing thermal power, researchers primarily optimize the interaction between ions and their surrounding environment.

[0004] Mechanical flexibility is another core requirement for thermoelectric materials in device packaging and multi-scenario adaptation. Traditional inorganic thermoelectric materials are rigid, which poses significant challenges in series integration and curved packaging; some organic thermoelectric materials suffer from insufficient toughness and cannot adapt to the needs of use in extreme environments.

[0005] In summary, traditional thermoelectric materials cannot simultaneously possess high thermal power, directional voltage output characteristics, and excellent mechanical flexibility. Therefore, developing a thermoelectric material that combines high thermal power, directional voltage output characteristics, and mechanical flexibility has become an urgent need in this field. Summary of the Invention

[0006] Based on this, this application provides an asymmetric ion gel thermoelectric material that combines high thermal power, directional voltage output, temperature responsiveness, and mechanical flexibility.

[0007] A flexible asymmetric ionic gel that responds to temperature and outputs a directional voltage, comprising chemically spliced ​​n-type ionic gel and p-type ionic gel, wherein the n-type ionic gel is obtained by polymerization of an n-type prepolymer solution and the p-type ionic gel is obtained by polymerization of a p-type prepolymer solution. The n-type prepolymer liquid comprises: 2,2,2-trifluoroethyl acrylate, 1-ethyl-3-methylimidazoline bis(trifluoromethylsulfonyl)imide, crosslinking agent and initiator; The p-type prepolymer liquid comprises: 2,2,2-trifluoroethyl acrylate, 1-ethyl-3-methylimidazoline bis(trifluoromethylsulfonyl)imide, 1-ethyl-3-methylimidazoline chloride, a crosslinking agent, and an initiator.

[0008] Traditional p-type and n-type thermoelectric materials generate voltage outputs corresponding to their respective dominant charge carriers when receiving temperature signals. However, when the temperature signal is reversed, their respective voltage outputs exhibit the same magnitude but opposite polarity as before the temperature reversal. This severely limits the ability to control the directionality of voltage, rectify signals, and efficiently integrate them into functional circuits. This application fabricates n-type and p-type ion gels as asymmetric ion gels, which can generate directional voltage outputs when input with alternating or randomly changing thermal signals, achieving electrothermal behavior similar to that of a diode.

[0009] The flexible asymmetric ionic gel, through the construction of an asymmetric structure, can achieve directional voltage output in response to temperature. The asymmetric structure is obtained by chemically cross-linking p-type and n-type ionic gels with similar components but opposite polarities.

[0010] The construction of asymmetric structures is a crucial factor affecting directional voltage output. This study employed the chemical splicing of p-type and n-type ion gels, and the use of EMIM within the p-type ion gel. + Cations and Cl - Strong intermolecular interactions occur between anions, forming ionic clusters. These clusters play a crucial role in thermally driven ion diffusion, and this interaction enables EMIM... + –Cl - Ion pairs possess relatively large heat transfer properties, thereby modulating the directionality and amount of thermal migration across the interface between p-type and n-type ion gels. If a physical splicing method is used—that is, after fabricating the p-type and n-type ion gels separately, placing them in contact with each other—the ion clusters cannot cross the interface between the two ion gels in this physically spliced ​​structure.

[0011] In the flexible asymmetric ionic gels obtained by chemical splicing, p-type ionic gels and n-type ionic gels have a large bonding force at the interface and are not prone to breakage during stretching.

[0012] The direction of temperature difference in flexible asymmetric ionic gels is defined as positive when the temperature at the p-end is greater than that at the n-end, and negative when the temperature at the p-end is less than that at the n-end. Under a positive temperature difference, the prepared asymmetric ionic gel has a positive output voltage, which is greater than the sum of the output voltages of the individual p-type and n-type gels under the same temperature difference. Meanwhile, under a negative temperature difference, the output voltage of the asymmetric ionic gel is close to zero.

[0013] The n-type ionogel of the asymmetric flexible asymmetric ionogel uses 1-ethyl-3-methylimidazoline bis(trifluoromethanesulfonyl)imide (EMIM TFSI) as the ionic liquid, and is copolymerized with 2,2,2-trifluoroethyl acrylate (TFEA) as the polymer monomer and ethylene glycol dimethacrylate as the crosslinking agent. The resulting PTFEA / IL ionogel is an n-type thermoelectric material, and the p-type portion is obtained by adding 1-ethyl-3-methylimidazoline chloride (EMIMCl) to the n-type formulation.

[0014] When a positive temperature difference is applied to the asymmetric ionic gel, the Seebeck coefficient is positive (e.g., +12.96 mV / K in Example 1 or +23.31 mV / K in Example 2); when a reverse temperature difference is applied, the Seebeck coefficient approaches 0. Under the opposite temperature difference conditions, a directional voltage output is exhibited.

[0015] Preferably, the flexible asymmetric ionogel has an ionic conductivity of 280 × 10⁻⁶ at 25°C. -3 S / m ~1000×10 -3 S / m. The flexible asymmetric ionic gel provided in this application has high ionic conductivity and good electrical conductivity, making it suitable for use as a sensor.

[0016] Several alternative methods are provided below, but they are not intended as additional limitations on the overall solution above. They are merely further additions or optimizations. Provided there are no technical or logical contradictions, each alternative method can be combined individually with respect to the overall solution above, or multiple alternative methods can be combined with each other.

[0017] Optionally, the mass of the 1-ethyl-3-methylimidazoline bis(trifluoromethanesulfonyl)imide is m1, the mass of the 2,2,2-trifluoroethyl acrylate is m2, and the value of m1 / m2 ranges from 1 to 3. More preferably, the mass of the 1-ethyl-3-methylimidazoline bis(trifluoromethanesulfonyl)imide is m1, the mass of the 2,2,2-trifluoroethyl acrylate is m2, and the value of m1 / m2 ranges from 1.5 to 2.5. In a preferred embodiment, m1:m2 is 6:4 or 7:3.

[0018] Optionally, the crosslinking agent is ethylene glycol diacrylate, the mass of the crosslinking agent is m3, and the value of m3 / (m1+m2) ranges from 0.5% to 1.5%.

[0019] Optionally, the initiator is 2-hydroxy-2-methylpropanone, and the mass of the initiator, m4 / (m1+m2), ranges from 0.5% to 1.5%.

[0020] Optionally, the mass of the 1-ethyl-3-methylimidazolium chloride is m5, and the value of m5 / m1 ranges from 3% to 6%.

[0021] Optionally, the flexible asymmetric ionic gel is prepared using a polytetrafluoroethylene (PTFE) mold, wherein the PTFE mold has a cavity, and the flexible asymmetric ionic gel is prepared using any of the following methods: (1) After filling part of the space of the mold cavity with n-type prepolymer liquid and performing free radical polymerization to obtain the n-type ionic gel, the remaining space of the mold cavity is filled with p-type prepolymer liquid and directly contacted with the n-type ionic gel. The p-type prepolymer liquid is then subjected to free radical polymerization to obtain the p-type ionic gel. (2) After filling part of the space of the mold cavity with p-type prepolymer liquid and performing free radical polymerization to obtain the p-type ionic gel, the remaining space of the mold cavity is filled with n-type prepolymer liquid and directly contacted with the p-type ionic gel. The n-type prepolymer liquid is then subjected to free radical polymerization to obtain the n-type ionic gel.

[0022] Optionally, in the same flexible asymmetric ionic gel, the n-type ionic gel and the p-type ionic gel have the same shape and size.

[0023] This application also provides a flexible temperature sensor, which includes at least one sensing unit. The sensing unit includes a flexible substrate, a first electrode, an ion gel layer, a second electrode, a flexible protective layer, and a signal processing circuit for processing electrical signals from the first electrode and the second electrode, arranged sequentially. The ion gel layer is a flexible asymmetric ion gel as described in any one of claims 1 to 7, and the p-type ion gel and n-type ion gel in the flexible asymmetric ion gel are respectively connected to the first electrode and the second electrode.

[0024] The flexible substrate, first electrode, second electrode, protective layer, and signal processing circuit of the flexible temperature sensor are implemented using existing technologies and will not be described in detail here. The contribution of this application is mainly based on the ion gel layer.

[0025] Optionally, the flexible temperature sensor includes at least two sensing units connected in series in a ring. Each sensing unit is arc-shaped, and each sensing unit consists of a flexible substrate, a first electrode, an ion gel layer, a second electrode, and a flexible protective layer in the radial direction of the ring from the inside to the outside. In the ion gel layer, p-type ion gel and n-type ion gel are arranged in the radial direction of the ring from the inside to the outside.

[0026] Optionally, in each sensing unit, the thickness of the flexible asymmetric ionic gel in the radial direction of the ring is 3 to 10 mm.

[0027] The flexible asymmetric ionic gel provided in this application combines high thermal power, directional voltage output, temperature responsiveness, and mechanical flexibility, and has broad application prospects in the field of thermoelectric materials. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of the flexible asymmetric ionic gel prepared in this application; Figure 2 (a) Seebeck coefficient of the flexible asymmetric ionic gel prepared in Example 1 under positive temperature difference; (b) Real-time temperature difference voltage curve of the flexible asymmetric ionic gel prepared in Example 1 under temperature difference cycling. Figure 3 The conductivity of the ionogels prepared in Examples 1, 2, 3, Comparative Example 1, and Comparative Example 2 at 25°C; Figure 4 (a) Seebeck coefficient of the flexible asymmetric ionic gel prepared in Example 2 under positive temperature difference; (b) Real-time temperature difference voltage curve of the flexible asymmetric ionic gel prepared in Example 2 under temperature difference cycling; Figure 5 (a) Seebeck coefficient of the flexible asymmetric ionic gel prepared in Example 3 under forward temperature difference; (b) Seebeck coefficient of the flexible asymmetric ionic gel prepared in Example 3 under reverse temperature difference; (c) Real-time temperature difference voltage curve of the flexible asymmetric ionic gel prepared in Example 3 under temperature difference cycling. Figure 6 (a) Seebeck coefficient of the ion gel prepared in Comparative Example 1; (b) Real-time temperature difference voltage curve of the ion gel prepared in Comparative Example 1 under temperature difference cycling. Figure 7 (a) Seebeck coefficient of the ion gel prepared in Comparative Example 2; (b) Real-time temperature difference voltage curve of the ion gel prepared in Comparative Example 2 under temperature difference cycling. Figure 8 (a) Seebeck coefficient of the ion gel prepared in Comparative Example 3; (b) Real-time temperature difference voltage curve of the ion gel prepared in Comparative Example 3 under temperature difference cycling. Figure 9 (a) Seebeck coefficient of the ion gel prepared in Comparative Example 4; (b) Real-time temperature difference voltage curve of the ion gel prepared in Comparative Example 4 under temperature difference cycling. Figure 10 (a) is a schematic diagram of a ring-shaped flexible temperature sensor, and (b) is a cross-sectional schematic diagram of the flexible sensor; Figure 11(a) shows the real-time temperature-voltage curve of a flexible temperature sensor with a ring structure used in a high-temperature detection device, with an inset of a photograph of the testing device; (b) shows the real-time temperature-voltage curve of a flexible temperature sensor with a ring structure used in a low-temperature detection device, with an inset of a photograph of the testing device. Figure 12 A flexible temperature sensor with a ring structure is used to perform real-time voltage response to temperature in a human arm; the illustration shows a photograph of the testing device. Figure 13 The stress-strain curves are for Examples 1, 2, 3, Comparative Example 1, and Comparative Example 2. Detailed Implementation

[0029] The present application will be further described below with reference to specific embodiments, but the present application is not limited to the following embodiments.

[0030] The materials and reagents used in the following embodiments are listed below: Monomer: 2,2,2-trifluoroethyl acrylate (TFEA, CAS: 407-47-6); Ionic liquids: 1-Ethyl-3-methylimidazoline bis(trifluoromethanesulfonyl)imine (EMIM TFSI, CAS: 174899-82-2); 1-Ethyl-3-methylimidazoline chloride (EMIMCl, CAS: 65039-09-0) Crosslinking agent: Ethylene glycol diacrylate (EGDMA, CAS: 2274-11-5); Initiator: 2-hydroxy-2-methylpropanone (HMPP, photoinitiator 1173).

[0031] Performance testing methods The thermoelectric properties of ionogels were characterized by measurements of Seebeck coefficient (S) and electrical conductivity.

[0032] Seebeck coefficient: The ionic Seebeck coefficient of the ionogel was obtained by measuring the temperature between two electrodes in a planar configuration. Each sample was tested in parallel three times at different temperature gradients. The ionic Seebeck coefficient value was obtained from the linear relationship between open-circuit voltage and temperature difference, and then the average value was taken as the final ionic Seebeck coefficient value of the sample. The open-circuit voltage difference (ΔV) between the two electrodes was measured using a DMM6500 digital multimeter, and the temperature difference (ΔT) was evaluated using a type K thermocouple and measured using a DMM6500 digital multimeter.

[0033] Conductivity: The ionic conductivity of the ionogel was determined by electrochemical impedance spectroscopy (EIS) using an electrochemical workstation (Autolab PGSTAT302N, Switzerland), with a voltage amplitude of 10 mV and a scan frequency from 100 kHz to 0.1 Hz. A sample measuring 2 cm × 2 cm was clamped between two stainless steel electrodes, ensuring that there were no air gaps between the sample and the electrodes.

[0034] Mechanical properties: Tensile tests were performed using a universal testing machine (model UH6502). Sample dimensions: 12mm (length) × 4mm (width) × 1mm (thickness) for tensile fracture. Figure 1 The structure shown, along Figure 1 (Stretch in the direction indicated by the middle arrow) at a stretching rate of 20 mm / min. Record the breaking strength and elongation at break.

[0035] Example 1 A method for preparing a flexible asymmetric ionic gel that outputs a directional voltage in response to temperature, comprising: (1) Preparation of n-type prepolymer solution, including the following steps: The monomer 2,2,2-trifluoroethyl acrylate (TFEA) was mixed with the ionic liquid 1-ethyl-3-methylimidazoline bis(trifluoromethylsulfonyl)imine to obtain a mixed solution. In the mixed solution, the mass of the ionic liquid was m1, and the mass of the monomer TFEA was m2, with m1:m2 = 6:4.

[0036] Add ethylene glycol diacrylate, a crosslinking agent, to the above mixed solution at a rate of 1 wt% (the mass of the crosslinking agent is m3, and m3 / (m1+m2) is the amount of crosslinking agent added); add an initiator (2-hydroxy-2-methylacetone) to the mixed solution at a rate of 1 wt% (the mass of the initiator is m4, and m4 / (m1+m2) is the amount of initiator added), to obtain an n-type prepolymer solution.

[0037] (2) Preparation of p-type prepolymer solution, including the following steps: Using the same method, an n-type prepolymer solution was prepared. Then, 5 wt% 1-ethyl-3-methylimidazolium chloride (EMIMCl) (the mass of EMIMCl is m5, and m5 / m1 is the amount of crosslinking agent added) was added to the n-type prepolymer solution to obtain a p-type prepolymer solution.

[0038] (3) Preparation of ionogel, including the following steps: The n-type prepolymer was injected into a polytetrafluoroethylene mold, with the amount added covering half of the mold area. Subsequently, free radical polymerization was initiated by ultraviolet light with a wavelength of λ=365nm and an irradiation time of 20min to obtain an n-type ionogel.

[0039] The p-type prepolymer was added to a mold containing an n-type ionic gel, and the remaining mold was covered. Free radical polymerization was initiated by ultraviolet light with a wavelength of λ=365nm and an irradiation time of 30min to prepare a flexible asymmetric ionic gel.

[0040] See Figure 1 As shown, the flexible ionogel prepared in Example 1 has an asymmetric structure. This asymmetry does not refer to geometric asymmetry, but rather that one half is an n-type ionogel and the other half is a p-type ionogel. The p-type and n-type ionogels are in direct contact, forming... Figure 1 The chemical interface shown.

[0041] See Figure 2 As shown, the flexible asymmetric ionic gel prepared in Example 1 has a Seebeck coefficient of +12.96 mV / K under a forward temperature difference; under a reverse temperature difference, the Seebeck coefficient is close to 0; exhibiting a diode-like effect, see [link to documentation]. Figure 3 As shown, the conductivity is 283.4 × 10⁻⁶. -3 S / m.

[0042] Example 2 The preparation method was the same as in Example 1, except that the mass ratio of 1-ethyl-3-methylimidazoline bis(trifluoromethanesulfonyl)imine to 2,2,2-trifluoroethyl acrylate was adjusted to 7:3, and the remaining raw materials and reaction conditions remained the same.

[0043] See Figure 4 As shown, the flexible asymmetric ionic gel prepared in Example 2 has a Seebeck coefficient of +23.31 mV / K under a forward temperature difference; under a reverse temperature difference, the Seebeck coefficient is close to 0; exhibiting a diode-like effect, see [link to documentation]. Figure 3 As shown, the conductivity is 483.9 × 10⁻⁶. -3 S / m.

[0044] Example 3 The preparation method was the same as in Example 1, except that the mass ratio of 1-ethyl-3-methylimidazoline bis(trifluoromethanesulfonyl)imine to 2,2,2-trifluoroethyl acrylate was adjusted to 8:2, and the remaining raw materials and reaction conditions remained the same.

[0045] See Figure 5 As shown, the flexible asymmetric ionic gel prepared in Example 3 exhibits a Seebeck coefficient of +18.43 mV / K under a forward temperature difference and -11.68 mV / K under a reverse temperature difference, without displaying a zero output voltage. (See also...) Figure 3 As shown, the conductivity is 999.6 × 10⁻⁶. -3 S / m.

[0046] Comparative Example 1 Step 1: Obtain the n-type prepolymer solution using the same preparation method as in Example 1; Step 2: Pour the n-type prepolymer liquid into a polytetrafluoroethylene mold, and initiate free radical polymerization by ultraviolet light. The wavelength of the ultraviolet light is λ=365nm and the irradiation time is 30min to prepare an n-type ionogel.

[0047] See Figure 6 As shown, the Seebeck coefficient of the n-type ionogel prepared in Comparative Example 1 is -0.91 mV / K. (See [reference needed]). Figure 3 As shown, the conductivity is 181.4 × 10⁻⁻¹ 3 S / m.

[0048] Comparative Example 2 Step 1: The p-type prepolymer solution was obtained using the same preparation method as in Example 1; Step 2: Pour the p-type prepolymer liquid into a polytetrafluoroethylene mold, and initiate free radical polymerization by ultraviolet light. The wavelength of the ultraviolet light is λ=365nm and the irradiation time is 30min to prepare the p-type ionogel.

[0049] See Figure 7 As shown, the Seebeck coefficient of the n-type ionogel prepared in Comparative Example 2 is +6.09 mV / K. (See [reference needed]). Figure 3 As shown, the conductivity is 195.6 × 10⁻⁶. -3 S / m.

[0050] Comparative Example 3 Step 1: Obtain the n-type prepolymer solution using the same preparation method as in Example 1; Step 2: Inject the n-type prepolymer liquid into the polytetrafluoroethylene mold, the amount of which is added is enough to cover half of the mold area. Then, initiate free radical polymerization by ultraviolet light. The wavelength of the ultraviolet light is λ=365nm and the irradiation time is 20min to carry out prepolymerization and obtain n-type ionogel. Step 3: Add the n-type prepolymer liquid to the mold containing the n-type ionic gel obtained in Step 2, cover the remaining mold, and initiate free radical polymerization by ultraviolet light. The wavelength of the ultraviolet light is λ=365nm and the irradiation time is 30min to prepare the n-type homogeneous ionic gel.

[0051] See Figure 8 As shown, the Seebeck coefficient of the n-type homogeneous ionogel prepared in Comparative Example 3 is -0.89 mV / K.

[0052] Comparative Example 4 Step 1: The p-type prepolymer solution was obtained using the same preparation method as in Example 1; Step 2: P-type prepolymer liquid is injected into a polytetrafluoroethylene mold, the amount of which is added is enough to cover half of the mold area. Then, free radical polymerization is initiated by ultraviolet light with a wavelength of λ=365nm and an irradiation time of 20min to carry out prepolymerization and obtain p-type ionogel. Step 3: Add the p-type prepolymer liquid to the mold containing the p-type ionogel obtained in Step 2, cover the remaining mold, and initiate free radical polymerization by ultraviolet light. The wavelength of the ultraviolet light is λ=365nm and the irradiation time is 30min to prepare the pp homogeneous ionogel.

[0053] See Figure 9 As shown, the Seebeck coefficient of the PP homogeneous ionogel prepared in Comparative Example 4 is +6.21 mV / K.

[0054] The stress-strain curves for Examples 1, 2, 3, Comparative Example 1, and Comparative Example 2 are shown below. Figure 13 As shown.

[0055] Application Example 1 See Figure 10 As shown, the flexible temperature sensor has a ring structure, which includes four sensing units connected in series. Each sensing unit includes, from the outside to the inside, a flexible protective layer 4 (i.e., the semi-transparent sheet in the figure), a first electrode, an ion gel layer, a second electrode, a flexible substrate 1 (i.e., the semi-transparent sheet in the figure), and a signal processing circuit (not shown in the figure) for processing the electrical signals of the first electrode and the second electrode. The ion gel layer uses the asymmetric flexible ion gel prepared in Example 1, and from the inside to the outside along the radial direction of the ring, it is a p-type ion gel (labeled 2 in the figure) and an n-type ion gel (labeled 3 in the figure).

[0056] The four sensing units in the flexible temperature sensor are connected via Figure 10 The copper electrode connection shown has two adjacent sensing units, namely the first sensing unit and the second sensing unit. One patch of the copper electrode 5 is attached to the p-type ion gel of the first sensing unit, and the other patch is attached to the n-type ion gel of the second sensing unit.

[0057] Figure 10 The signal processing circuit is not shown in the figure. The circuit signals from the first electrode 7 and the second electrode 6 are connected to the signal processing circuit. When the asymmetric flexible ion gel senses a temperature change, it exhibits a large positive output voltage (high temperature inside the ring structure) and a near-zero output voltage (low temperature inside the ring structure), thus realizing temperature sensing.

[0058] in accordance with Figure 11The illustration shows a test setup for voltage response to water temperature. The setup includes a ring-shaped flexible temperature sensor, a thermocouple, and a beaker. The flexible temperature sensor consists of four sensing units. Each asymmetric flexible ionogel has dimensions of 20mm in length, 10mm in width, and 5mm in height (i.e., radial thickness). The circumferential spacing between two adjacent asymmetric flexible ionogels is 10mm.

[0059] See Figure 11 As shown in (a), a ring-shaped flexible temperature sensor was mounted on the outside of a beaker. Hot water was added to the beaker, and the dynamic processes of temperature and voltage were recorded. Test results show that the device outputs a positive voltage signal, generating a voltage difference of approximately 256 mV, and exhibits real-time responsiveness. See also Figure 11 As shown in (b), when cold water is added to the beaker, the test results show that the device outputs a voltage signal close to 0 (about 7mV).

[0060] See Figure 12 As shown, a ring-shaped flexible temperature sensor is used for temperature detection on a human arm. The illustration shows the ring-shaped flexible temperature sensor worn on a human arm, recording the dynamic process of the voltage signal. Test results show that the device generates a positive voltage output upon contact with the arm, and can continuously generate voltage by utilizing the temperature difference between the human body and the environment.

[0061] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0062] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A flexible asymmetric ionic gel that outputs a directional voltage in response to temperature, characterized in that, The invention includes chemically spliced ​​n-type ionic gels and p-type ionic gels, wherein the n-type ionic gel is obtained by polymerization of an n-type prepolymer solution and the p-type ionic gel is obtained by polymerization of a p-type prepolymer solution. The n-type prepolymer liquid comprises: 2,2,2-trifluoroethyl acrylate, 1-ethyl-3-methylimidazoline bis(trifluoromethylsulfonyl)imide, crosslinking agent and initiator; The p-type prepolymer liquid comprises: 2,2,2-trifluoroethyl acrylate, 1-ethyl-3-methylimidazoline bis(trifluoromethylsulfonyl)imide, 1-ethyl-3-methylimidazoline chloride, a crosslinking agent, and an initiator.

2. The flexible asymmetric ionic gel with directional voltage output in response to temperature according to claim 1, characterized in that, The mass of the 1-ethyl-3-methylimidazoline bis(trifluoromethanesulfonyl)imine is m1, the mass of the 2,2,2-trifluoroethyl acrylate is m2, and the value of m1 / m2 ranges from 1 to 3.

3. The flexible asymmetric ionic gel with directional voltage output in response to temperature as described in claim 1, characterized in that, The crosslinking agent is ethylene glycol diacrylate, the mass of the crosslinking agent is m3, and the value of m3 / (m1+m2) ranges from 0.5% to 1.5%.

4. The flexible asymmetric ionic gel with directional voltage output in response to temperature according to claim 1, characterized in that, The initiator is 2-hydroxy-2-methylpropanone, and the mass of the initiator, m4 / (m1+m2), ranges from 0.5% to 1.5%.

5. The flexible asymmetric ionic gel with directional voltage output in response to temperature according to claim 1, characterized in that, The mass of the 1-ethyl-3-methylimidazolium chloride is m5, and the value of m5 / m1 ranges from 3% to 6%.

6. The flexible asymmetric ionic gel with directional voltage output in response to temperature according to claim 1, characterized in that, The flexible asymmetric ionic gel is prepared using a polytetrafluoroethylene (PTFE) mold, wherein the PTFE mold has a cavity, and the flexible asymmetric ionic gel is prepared using any of the following methods: (1) After filling part of the space of the mold cavity with n-type prepolymer liquid and performing free radical polymerization to obtain the n-type ionic gel, the remaining space of the mold cavity is filled with p-type prepolymer liquid and directly contacted with the n-type ionic gel. The p-type prepolymer liquid is then subjected to free radical polymerization to obtain the p-type ionic gel. (2) After filling part of the space of the mold cavity with p-type prepolymer liquid and performing free radical polymerization to obtain the p-type ionic gel, the remaining space of the mold cavity is filled with n-type prepolymer liquid and directly contacted with the p-type ionic gel. The n-type prepolymer liquid is then subjected to free radical polymerization to obtain the n-type ionic gel.

7. The flexible asymmetric ionic gel with directional voltage output in response to temperature according to claim 1, characterized in that, In the same flexible asymmetric ionic gel, the n-type ionic gel and the p-type ionic gel have the same shape and size.

8. A flexible temperature sensor, characterized in that, The flexible temperature sensor includes at least one sensing unit, which includes a flexible substrate, a first electrode, an ion gel layer, a second electrode, a flexible protective layer, and a signal processing circuit for processing electrical signals from the first electrode and the second electrode, arranged sequentially. The ion gel layer is a flexible asymmetric ion gel as described in any one of claims 1 to 7, and the p-type ion gel and n-type ion gel in the flexible asymmetric ion gel are respectively connected to the first electrode and the second electrode.

9. The flexible temperature sensor according to claim 8, characterized in that, The flexible temperature sensor includes at least two interconnected sensing units arranged in a ring. Each sensing unit is arc-shaped, and each sensing unit consists of a flexible substrate, a first electrode, an ion gel layer, a second electrode, and a flexible protective layer in the radial direction of the ring from the inside to the outside. In the ion gel layer, p-type ion gel and n-type ion gel are arranged in the radial direction of the ring from the inside to the outside.

10. The flexible temperature sensor according to claim 9, characterized in that, In each sensing unit, the thickness of the flexible asymmetric ionic gel in the radial direction of the ring is 3~10 mm.

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