Fully-integrated self-powered electrochromic gel strain sensor and application thereof

Abstract

The invention discloses a fully-integrated self-powered electrochromic gel strain sensor and application thereof, the fully-integrated self-powered electrochromic gel strain sensor comprises an all-solid-state super capacitor, a current fluctuation signal monitoring device and a strain sensor, and the all-solid-state super capacitor is charged through an electrochemical workstation. According to the invention, the electrochromic gel and the conductive glass are respectively assembled into an all-solid-state super capacitor, and the all-solid-state super capacitor is combined with the conductive metal foil to construct a strain sensor, so that the multifunctional application of the material is successfully realized. The self-powered strain sensing system is formed by integrating the strain sensor and the sensor, and the system not only can visualize the change of electric quantity in real time, but also can monitor the movement of a human body at any time, and has high portability and functionality.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochromic gels, and particularly relates to a fully integrated self-powered electrochromic gel strain sensor and its applications. Background Art

[0002] As a core component of wearable devices, strain sensors, through precise design, can continuously and real-time monitor physiological parameters such as human body movement, heart rate, and pulse. However, most traditional strain sensors rely on semiconductor and metal materials. Although these materials have significant performance advantages, their high rigidity and limited biocompatibility severely limit their wide application and further development in the field of human health monitoring. Therefore, developing innovative strain sensors with flexibility, portability, and excellent biocompatibility has become a key problem that urgently needs to be solved in the current scientific research field.

[0003] Gel materials based on unique polymer network structures not only exhibit excellent mechanical flexibility but also possess outstanding biocompatibility, making them ideal candidate materials for constructing advanced strain sensors. However, traditional gel materials usually rely on large external power supplies for power supply. This limitation not only hinders their popularization but also restricts the expansion and exertion of functions to a certain extent.

[0004] To solve the above problems, Huang et al. carried out relevant research and prepared an integrated self-powered system based on a polyvinyl alcohol (PVA) / polyacrylamide-acrylic acid (PAMAA) / glycerol (Gly) / sodium chloride (NaCl) double-network ionic organohydrogel, which consists of a strain sensor and a flexible all-solid-state supercapacitor (J. Huang, S. Peng, J. Gu, G. Chen, J. Gao, J. Zhang, L. Hou, X. Yang, X. Jiang, L. Guan, Self-powered integrated system of a strain sensor and flexible all-solid-state supercapacitor by using a high-performance ionic organohydrogel, Mater. Horiz. 7(8)(2020)2085-2096.). Although this self-powered system successfully solves the problem of relying on large external power supplies for energy supply, there are still some deficiencies. For example, the structure of this system is relatively complex, including multiple layers, and in actual application scenarios, the energy state of the external power supply cannot be effectively monitored in real time.

[0005] To address this problem, developing an integrated, miniaturized energy storage system with energy visualization function has become a key technical path to improve the self-powered ability of strain sensors and get rid of the dependence on external power sources. This technological breakthrough is expected to promote the development of strain sensors in a more compact and convenient direction, providing strong technical support for cutting-edge fields such as smart health monitoring and wearable devices, and also laying a solid scientific foundation for the continuous progress of human health and the widespread application of smart technology. Summary of the invention

[0006] The present invention overcomes the defects of the prior art and provides a fully integrated self-powered electrochromic gel strain sensor.

[0007] Another object of the present invention is to provide an application of the above fully integrated self-powered electrochromic gel strain sensor. The technical solution of the present invention is as follows:

[0008] A fully integrated self-powered electrochromic gel strain sensor includes an all-solid-state supercapacitor, a current fluctuation signal monitoring device and a strain sensor. The all-solid-state supercapacitor is charged through an electrochemical workstation, wherein:

[0009] The all-solid-state supercapacitor comprises two conductive glasses and an electrochromic gel sandwiched between the two conductive glasses.

[0010] The strain sensor comprises two conductive metal foils and an electrochromic gel sandwiched between the two conductive metal foils, a conductive glass is electrically connected to the conductive metal foil through a wire, and a current fluctuation signal monitoring device is arranged on the wire.

[0011] Another conductive metal foil is electrically connected to another conductive glass through another conductive wire.

[0012] The electrochromic gel is prepared by mixed reaction of acrylamide monomer, carboxymethyl cellulose solution, N,N'-methylenebisacrylamide, lithium chloride, azobisisobutyronitrile, viologen derivative and ferrocene.

[0013] The structural formula of the viologen derivative is

[0014] In a preferred embodiment of the present invention, the preparation method of the electrochromic gel comprises: mixing acrylamide monomer and 2wt% carboxymethyl cellulose solution in a mass ratio of 1:1.5, then adding N,N'-methylenebisacrylamide, lithium chloride, azobisisobutyronitrile, viologen derivative and ferrocene, stirring well and pouring into a mold, reacting at 80-100°C for 1.5-2h to obtain the electrochromic gel.

[0015] Further preferably, the solvent of the 2 wt % carboxymethyl cellulose solution is a mixture of DMSO and H2O in a volume ratio of 3:2.

[0016] More preferably, the mass ratio of N,N'-methylenebisacrylamide, lithium chloride and azobisisobutyronitrile is 0.01-0.015:0.5-1.2:0.01.

[0017] Even more preferably, the mass ratio of the viologen derivative and ferrocene is 8.8:1.

[0018] In a preferred embodiment of the present invention, the conductive glass is made of ITO or FTO.

[0019] In a preferred embodiment of the present invention, the conductive metal foil is made of copper or zinc.

[0020] In a preferred embodiment of the present invention, the current fluctuation signal monitoring device includes an ammeter and a multimeter.

[0021] Use of the above-mentioned fully integrated self-powered electrochromic gel strain sensor in the preparation of a human motion state monitoring device.

[0022] A human motion state monitoring device having the above-mentioned fully integrated self-powered electrochromic gel strain sensor.

[0023] The beneficial effects of the present invention are:

[0024] 1. The present invention has excellent color-changing performance. When a step voltage (-0.8V to 2.2V) is applied for cyclic testing and the in-situ transmittance spectral changes are recorded, the change amplitude of the transmittance of the electrochromic gel in the initial state can reach 53.1%. After 3500 seconds of continuous operation, the transmittance stabilizes at 42.6%, and the optical transmittance remains at 80%, fully demonstrating the stability and high performance of the material during long-term operation.

[0025] 2. The electrochromic gel prepared by the present invention and the conductive glass are combined to form a all-solid-state supercapacitor. After 1900 cycles, the all-solid-state supercapacitor can still maintain 76.7% of the original areal capacitance, and the Coulomb efficiency is stably maintained above 91%, showing excellent cycle stability. In addition, the all-solid-state supercapacitor also has the ability to continuously power a light bulb, proving its excellent performance in energy storage and release.

[0026] 3. The present invention assembles the electrochromic gel with the conductive glass into an all-solid-state supercapacitor respectively, and combines it with the conductive metal foil to construct a strain sensor, successfully realizing the multifunctional application of the material. By integrating the two, a self-powered strain sensing system is formed. This system can not only visualize the power change in real time, but also monitor human motion at any time, with both high portability and functionality. Description of the Drawings

[0027] Figure 1 This is a schematic structural diagram of the fully integrated self-powered electrochromic gel strain sensor in Embodiment 1 of the present invention.

[0028] Figure 2 This is the spectral cycle stability of the electrochromic gel in Embodiment 1 of the present invention at 571 nm.

[0029] Figure 3 This is the constant current charge-discharge cycle performance of the all-solid-state supercapacitor in Embodiment 1 of the present invention in the voltage window of -0.8 - 2.2 V.

[0030] Figure 4 This is a digital photo of the all-solid-state supercapacitor in Embodiment 1 of the present invention in series to light up an LED lamp.

[0031] Figure 5 Showing the experimental results of the fully integrated self-powered electrochromic gel strain sensor in Embodiment 1 of the present invention under 50% strain for 12 cycles of stretching and relaxation.

[0032] Figure 6 Showing the time-current response curve of the fully integrated self-powered electrochromic gel strain sensor in Embodiment 1 of the present invention under 20% strain for 60 cycles.

[0033] Figure 7 Showing the digital image and the corresponding time-current response curve of the fully integrated self-powered electrochromic gel strain sensor in Embodiment 1 of the present invention in human neck movement monitoring.

[0034] Figure 8 Showing the digital image and the corresponding time-current response curve of the fully integrated self-powered electrochromic gel strain sensor in Embodiment 1 of the present invention in human finger movement monitoring.

[0035] Figure 9 Showing the digital image and the corresponding time-current response curve of the fully integrated self-powered electrochromic gel strain sensor in Embodiment 1 of the present invention in human arm movement monitoring.

[0036] Figure 10 Showing the digital image and the corresponding time-current response curve of the fully integrated self-powered electrochromic gel strain sensor in Embodiment 1 of the present invention in human walking and running movement monitoring. Detailed implementation manners

[0037] The technical solutions of the present invention will be further described and illustrated below through specific implementation manners in conjunction with the accompanying drawings.

[0038] Embodiment 1

[0039] (1) Preparation of electrochromic gel: 1 g of acrylamide monomer was mixed with 1.5 g of 2 wt% carboxymethyl cellulose solution (the solvent was a mixture of DMSO and H2O in a volume ratio of 3:2), and 0.015 g of N,N'-methylenebisacrylamide, 1 g of lithium chloride, 0.01 g of azobisisobutyronitrile, 0.1158 g of viologen derivative (dissolved in 1.2 mL of a mixed solvent, which was a mixture of DMSO and H2O in a volume ratio of 1:5), and 0.0132 g of ferrocene (dissolved in 0.3 mL of DMSO) were added. After stirring well, the mixed solution was poured into a mold. The system was reacted at 90 °C for 2 h to obtain the target product.

[0040] The structural formula of the above viologen derivative is

[0041] (2) Construction of all-solid-state supercapacitor: Two pieces of ITO conductive glass were respectively placed on the upper and lower surfaces of the above electrochromic gel to construct an all-solid-state supercapacitor structure.

[0042] (3) Construction of strain sensor: Two pieces of copper foil were respectively placed on the upper and lower surfaces of the above electrochromic gel to form a strain sensor.

[0043] (4) Construction of fully integrated self-powered electrochromic gel strain sensor: The above all-solid-state supercapacitor was charged by an electrochemical workstation. After charging, it was connected to the above strain sensor through a wire to provide a stable power supply for the sensor, and an ammeter was connected in series in the circuit. The system could capture the current fluctuations caused by strain in real time, so as to accurately monitor the dynamic response of strain.

[0044] As Figure 1 shown, the fully integrated self-powered electrochromic gel strain sensor prepared in this example consisted of two parts: on the one hand, an all-solid-state supercapacitor assembled by electrochromic gel and two pieces of ITO conductive glass was connected to an electrochemical workstation for charging; on the other hand, after the supercapacitor was charged, it was connected to the electrochromic gel strain sensor as a power supply to provide continuous power supply for it. In addition, by connecting an ammeter in series, the change of current during the movement process was monitored in real time, so as to realize the detection and analysis of the movement state.

[0045] The all-solid-state supercapacitor was used in combination with an electrochemical workstation, and a step voltage of -0.8 V to 2.2 V was applied by using a two-electrode test method. During this process, it was simultaneously connected to an ultraviolet-visible spectrophotometer to monitor and record the dynamic response curve of the transmittance changing with voltage at a wavelength of λ = 571 nm in real time. As Figure 2As shown, the transmittance change of the all-solid-state supercapacitor prepared in this example can reach 53.1% in the initial state. After 3500 seconds of continuous operation, the transmittance stabilizes at 42.6%, and the optical transmittance remains above 80%, fully demonstrating its excellent stability and high efficiency in electrochromic performance during long-term operation.

[0046] The all-solid-state supercapacitor was combined with an electrochemical workstation, and the two-electrode method was used to perform charge-discharge tests in a voltage window of -0.8V to 2.2V to evaluate its electrochemical performance. As Figure 3 shown, after 1900 charge-discharge cycles, the all-solid-state supercapacitor in this example still maintained 79% of its initial areal capacitance, and the Coulomb efficiency was stably maintained above 92.9%, fully demonstrating its excellent charge-discharge cycle stability and excellent long-term performance.

[0047] As Figure 4 shown, after two all-solid-state supercapacitors in this example were configured in series, they could effectively provide electrical energy for a light-emitting diode (LED), verifying its feasibility and performance in practical applications.

[0048] After the all-solid-state supercapacitor was charged through an electrochemical workstation, it was connected to a strain sensor with a wire and an ammeter was connected in series to monitor the change in the current response of the strain sensor during deformation. Figure 5 is the 12-cycle stretching and relaxation of the fully integrated self-powered electrochromic gel strain sensor in this example at 50% strain. As Figure 5 shown, due to the energy consumption caused by the self-discharge process in the fully integrated self-powered electrochromic gel strain sensor, both the current and potential electronic signals showed a similar attenuation trend. When mechanical strain was applied, the strain sensor based on the electrochromic gel was stretched, resulting in a significant decrease in current (showing an inverse relationship with the resistance change). In addition, the current of the sensor remained stable in the holding state after the strain was released. This self-powered strain sensor demonstrated excellent sensitivity and long-term stability.

[0049] Figure 6 is the time-current response curve of the fully integrated self-powered electrochromic gel strain sensor in this example at 20% strain for 60 cycles. As Figure 6 shown, when the fully integrated self-powered electrochromic gel strain sensor was cyclically stretched and released at a constant strain of 50%, the current signal of the sensor changed periodically and stably. Obviously, the current decreased. However, the relative current change (ΔI / I0; ΔI is the relative current varying with strain, and I0 is the initial current before strain) remained almost unchanged during 60 cycles of loading.

[0050] Figures 7 to 10Digital images and corresponding time-current response curves of the fully integrated self-powered electrochromic gel strain sensor of this embodiment in the monitoring of human neck, finger, arm, walking, and running movements are shown below. As Figures 7 to 10 shown, the current responses of the fully integrated self-powered electrochromic gel strain sensor under different motion states such as neck, finger, arm, walking, and running show different changing trends. This indicates that the electrochromic gel strain sensor can be effectively driven by a all-solid-state supercapacitor and has the ability to comprehensively monitor various human movements.

[0051] Example 2

[0052] The difference from Example 1 is that 0.01 g of N,N-methylenebisacrylamide and 0.5 g of lithium chloride are added.

[0053] Example 3

[0054] The difference from Example 1 is that the reaction is carried out at 100 °C for 1.5 h.

[0055] Example 4

[0056] The difference from Example 1 is that two pieces of FTO conductive glass are respectively placed on the upper and lower surfaces of the above electrochromic gel, and a all-solid-state supercapacitor structure can be constructed.

[0057] Example 5

[0058] The difference from Example 1 is that two pieces of zinc foil are respectively placed on the upper and lower surfaces of the above electrochromic gel, and a strain sensor can be formed.

[0059] The above is only the preferred embodiment of the present invention, and thus the scope of implementation of the present invention cannot be limited thereby. That is, equivalent changes and modifications made according to the scope of the present invention patent and the content of the specification should still fall within the scope covered by the present invention.

Claims

1. A fully integrated self-powered electrochromic gel strain sensor, characterized in that: The invention comprises an all-solid-state supercapacitor, a current fluctuation signal monitoring device and a strain sensor. The all-solid-state supercapacitor is charged through an electrochemical workstation, wherein: The all-solid-state supercapacitor comprises two conductive glasses and an electrochromic gel sandwiched between the two conductive glasses. The strain sensor includes two conductive metal foils and an electrochromic gel sandwiched between the two conductive metal foils. A conductive glass is electrically connected to a conductive metal foil through a conductive wire, and a current fluctuation signal monitoring device is arranged on the conductive wire. Another conductive metal foil is electrically connected to another conductive glass through another conductive wire. The electrochromic gel is prepared by mixed reaction of acrylamide monomer, carboxymethyl cellulose solution, N,N'-methylenebisacrylamide, lithium chloride, azobisisobutyronitrile, viologen derivative and ferrocene. The structural formula of the viologen derivative is 2. A fully integrated self-powered electrochromic gel strain sensor as claimed in claim 1, characterized in that: The preparation method of the electrochromic gel comprises: mixing acrylamide monomer and 2wt% carboxymethyl cellulose solution at a mass ratio of 1:1.5, then adding N,N'-methylenebisacrylamide, lithium chloride, azobisisobutyronitrile, viologen derivative and ferrocene, stirring well and pouring into a mold, reacting at 80-100°C for 1.5-2h to obtain the electrochromic gel.

3. A fully integrated self-powered electrochromic gel strain sensor as claimed in claim 2, characterized in that: The solvent of the 2 wt % carboxymethyl cellulose solution is a mixture of DMS and H 2 O in a volume ratio of 3:

2.

4. A fully integrated self-powered electrochromic gel strain sensor as claimed in claim 3, characterized in that: The mass ratio of the N,N'-methylenebisacrylamide, lithium chloride and azobisisobutyronitrile is 0.01-0.015:0.5-1.2:0.

01.

5. A fully integrated self-powered electrochromic gel strain sensor as claimed in claim 4, characterized in that: The mass ratio of the viologen derivative to ferrocene is 8.8:

1.

6. A fully integrated self-powered electrochromic gel strain sensor according to any one of claims 1 to 5, characterized in that: The conductive glass is made of ITO or FTO.

7. A fully integrated self-powered electrochromic gel strain sensor according to any one of claims 1 to 5, characterized in that: The conductive metal foil is made of copper or zinc.

8. A fully integrated self-powered electrochromic gel strain sensor according to any one of claims 1 to 5, characterized in that: The current fluctuation signal monitoring device comprises an ammeter and a multimeter.

9. Use of a fully integrated self-powered electrochromic gel strain sensor according to any one of claims 1 to 8 in preparing a human motion state monitoring device.

10. A human body motion state monitoring device, characterized in that: The invention has the fully integrated self-powered electrochromic gel strain sensor according to any one of claims 1 to 8.

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