Electrochemically self-powered static / dynamic tensile strain sensor and method of making the same

Abstract

The electrochemical self-powered static / dynamic tensile strain sensor and the preparation method thereof disclosed by the application belong to the technical field of flexible strain sensors and flexible wearable electronics, and specifically comprises a latex tube, an elastic thread penetrating through the latex tube, and two electrodes with different activities fixed at two ends of the elastic thread / latex tube respectively; the elastic thread is dip-coated with a sensitive material salt solution, so that oxidation-reduction reactions occur at the two electrodes, a sensing voltage / current is output, and self-power supply is realized; by stretching the elastic thread / latex tube, the internal resistance of the sensor is increased, the sensing current output is reduced, and strain sensing is realized; the self-power supply of the sensor is realized based on the principle of a primary cell, the strain detection is realized by using the elastic thread dip-coated with the sensitive material salt solution, the detection requirements of static strain and dynamic strain are simultaneously met, and the defects that the piezoelectric and triboelectric strain sensors cannot detect static strain are solved.

Description

Technical Field

[0001] This invention belongs to the field of flexible strain sensors and flexible wearable electronics technology, specifically relating to electrochemically self-powered static / dynamic tensile strain sensors and their fabrication methods. Background Technology

[0002] Flexible strain sensors are widely used in healthcare, human-computer interaction, intelligent robots, smart buildings, and aircraft. Currently, flexible strain sensors mainly include resistive, capacitive, piezoelectric, and triboelectric types. Patent CN108332647A discloses a flexible resistive strain sensor, comprising an insulating flexible substrate and a metallic glass film, with the metallic glass film deposited on the flexible substrate as the strain-sensitive material. Patent CN 112815823A discloses a flexible high-tensile strain sensor based on a flexible planar capacitor, including functional components, an insulating encapsulation component, a connection component, and a lead-out electrode component. Patent CN 113358016A discloses a flexible strain sensor based on the piezoelectric effect, including a flexible piezoelectric structure, two electrode lead structures, and two insulating encapsulation layers. Patent CN 114438657A discloses a low-cost triboelectric knitted spacer fabric with a composite layer structure, consisting of a top layer, a spacer layer, and a bottom layer from top to bottom, with the top and bottom layers connected by the spacer layer. It's worth noting that resistive and capacitive strain sensors require an external power supply to operate normally. Although piezoelectric and triboelectric strain sensors can be self-powered, they can only detect dynamic strain and cannot meet the needs of static strain detection, such as: structural deformation monitoring of buildings (bridges, houses, etc.), robot attitude perception, and aircraft attitude perception. Summary of the Invention

[0003] The purpose of this invention is to address the problems in the prior art by providing an electrochemically self-powered static / dynamic tensile strain sensor and its fabrication method, which simultaneously meets the requirements for detecting both static and dynamic strain.

[0004] The technical solution adopted in this invention is as follows:

[0005] An electrochemically self-powered static / dynamic tensile strain sensor is characterized by comprising a latex tube, an elastic wire passing through the latex tube, and two electrodes with different reactivity fixed at the two ends of the elastic wire / latex tube respectively; the elastic wire is coated with a sensitive material salt solution, causing an oxidation-reduction reaction at the two electrodes to output a sensing voltage / current, thus achieving self-powering; by stretching the elastic wire / latex tube, the internal resistance of the sensor is increased, the sensing current output is reduced, and strain sensing is achieved.

[0006] Furthermore, the elastic thread is made of polyester or nylon.

[0007] Furthermore, the number of elastic wires is 1 to 10. By increasing the number of elastic wires (equivalent to increasing the cross-sectional area of ​​the sensor), the internal resistance of the sensor is reduced, thereby increasing the sensing current output.

[0008] Furthermore, the sensitive material salt solution is a conductive material salt solution, specifically one of the following: carbon nanotube / lithium chloride solution, carbon black / lithium chloride solution, MXene (two-dimensional transition metal carbide, nitride, or carbonitride) / lithium chloride solution, graphene / lithium chloride solution, carbon nanotube / sodium chloride solution, carbon black / sodium chloride solution, MXene (two-dimensional transition metal carbide, nitride, or carbonitride) / sodium chloride solution, and graphene / sodium chloride solution. The salt provides the sensor with freely moving ions, ensuring redox reactions occur at both electrodes. The conductive material reduces the sensor's internal resistance and increases the sensing current output. Furthermore, under tensile strain, it increases the distance between the conductive materials, leading to increased internal resistance and decreased sensing current output, thus achieving strain sensing.

[0009] Furthermore, the concentration of the conductive material in the conductive material salt solution is 1–10 wt%, and the concentration of the salt is 0.5–2.0 mol / L.

[0010] Furthermore, the elastic wire is immersed in a salt solution of a sensitive material for 5–15 minutes.

[0011] Furthermore, the two electrodes with different reactivity are one of the following: copper-aluminum electrode, copper-zinc electrode, copper-silver electrode, carbon-graphite / manganese dioxide electrode, and zinc-manganese / graphite electrode.

[0012] Furthermore, the latex tube is used to encapsulate the elastic wire to prevent the loss of water molecules from the sensitive material's salt solution, ensuring the sensor's long-term power generation.

[0013] Furthermore, the electrochemically self-powered static / dynamic tensile strain sensor has a sensing current output under both static and dynamic strain conditions.

[0014] This invention also proposes a method for fabricating the above-mentioned electrochemically self-powered static / dynamic tensile strain sensor, characterized by comprising the following steps:

[0015] (1) Immerse the elastic cord in a sensitive material salt solution for 5 to 15 minutes;

[0016] (2) Pass the elastic cord through the latex tube;

[0017] (3) Attach two electrodes with different reactivity to both sides of the elastic wire / latex tube respectively.

[0018] The beneficial effects of this invention are as follows:

[0019] The electrochemical self-powered static / dynamic tensile strain sensor and its preparation method proposed in this invention realize the self-powering of the sensor based on the principle of galvanic cells, and realize strain detection by using the elastic lines of the salt solution of the sensitive material dipped in it. It simultaneously meets the detection requirements of static strain and dynamic strain, and solves the shortcomings of piezoelectric and triboelectric strain sensors, such as the inability to detect static strain. Attached Figure Description

[0020] Figure 1 A three-dimensional perspective view of the electrochemically self-powered static / dynamic tensile strain sensor provided in Example 1;

[0021] Figure 2 A front view of the electrochemically self-powered static / dynamic tensile strain sensor provided in Example 1;

[0022] Figure 3 A side view of the electrochemically self-powered static / dynamic tensile strain sensor provided in Example 1;

[0023] Figure 4 A top view of the electrochemically self-powered static / dynamic tensile strain sensor provided in Example 1;

[0024] Figure 5 1-1 cross-sectional view of the electrochemically self-powered static / dynamic tensile strain sensor provided in Example 1;

[0025] Figure 6 Output voltage and current curves of the electrochemical self-powered static / dynamic tensile strain sensor provided in Example 1 under different load resistances;

[0026] Figure 7 The current response curves of the electrochemically self-powered static / dynamic tensile strain sensor provided in Example 1 under different strains;

[0027] Figure 8 Real-time current response curve of the electrochemically self-powered static / dynamic tensile strain sensor provided in Example 1 at 20% strain;

[0028] Figure 9 The real-time current response curve of the electrochemically self-powered static / dynamic tensile strain sensor provided in Example 1 to finger bending;

[0029] Figure label:

[0030] 1 is an elastic wire, 2 is a latex tube, and 3 and 4 are two electrodes with different reactivity. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0032] Example 1

[0033] This embodiment provides an electrochemically self-powered static / dynamic tensile strain sensor, the structure of which is as follows: Figures 1-5 As shown, it includes a latex tube 2, an elastic wire 1 passing through the latex tube 2, and two electrodes 3 and 4 with different reactivity fixed at the two ends of the elastic wire 1 / latex tube 2 respectively.

[0034] Among them, the elastic thread 1 is made of polyester, has one strand, is 3cm long, and is coated with a carbon nanotube (10wt%) / lithium chloride (1.0mol / L) salt solution; the two electrodes 3 and 4 with different reactivity are copper-aluminum electrodes.

[0035] The method for preparing an electrochemically self-powered static / dynamic tensile strain sensor in this embodiment includes the following steps:

[0036] Step 1: Immerse one elastic cord 1 in a carbon nanotube (10wt%) / lithium chloride (1.0mol / L) salt solution for 15 minutes;

[0037] Step 2: Pass the elastic cord 1 through the latex tube 2;

[0038] Step 3: Attach the copper tape and aluminum tape to both ends of the elastic cord 1 / latex tube 2 respectively.

[0039] In this embodiment, since the elastic wire 1 is coated with a carbon nanotube (10wt%) / lithium chloride (1.0mol / L) salt solution, redox reactions occur at the two electrodes 3 and 4. Based on the principle of a galvanic cell, the sensing voltage / current is output, achieving self-powered operation. The lithium chloride in the carbon nanotube (10wt%) / lithium chloride (1.0mol / L) salt solution provides freely moving ions for the sensor, ensuring that redox reactions occur at the two electrodes 3 and 4. The carbon nanotubes can reduce the internal resistance of the sensor and increase the sensing current output. More importantly, when the elastic wire / latex tube is stretched, the distance between the carbon nanotubes increases, leading to an increase in the internal resistance of the sensor and a decrease in the sensing current output, thereby realizing strain sensing, including static strain sensing and dynamic strain sensing.

[0040] Figure 6 The output voltage and current curves of the electrochemically self-powered static / dynamic tensile strain sensor under different load resistances demonstrate that the sensor achieves self-powering.

[0041] The current response of the sensor is defined as ΔI / I0, where I0 is the output current of the sensor when it is not subjected to strain, and ΔI is the current change of the sensor when it is subjected to strain. The strain sensitivity of the sensor is defined as S = δ(ΔI / I0) / δ(ε), where δ(ΔI / I0) is a small increment of ΔI / I0, ε is the strain applied to the sensor, and δ(ε) is a small increment of ε. Figure 7 The current response curves of the electrochemically self-powered static / dynamic tensile strain sensor under different strains are shown. It can be seen that as the strain ε increases, the current response ΔI / I0 gradually decreases, demonstrating the self-powered strain detection function of the sensor. Among them, S1=1.21 and S2=0.18 are the strain sensitivities of the sensor in the 50% strain range and the 50%~100% strain range, respectively.

[0042] Figure 8 The real-time current response curve of the electrochemically self-powered static / dynamic tensile strain sensor under 20% strain is shown. When the sensor is subjected to strain from 2.9 s, a significant current response is observed. This response continues until strain loading is complete at 3.8 s, during which the strain dynamically increases (dynamic strain) from 2.9 s to 3.8 s, and the sensor's current response also exhibits dynamic growth. The strain is maintained from 3.8 s to 6.8 s (static strain), during which the sensor's current response remains stable. From 6.8 s onwards, strain is unloaded until 8 s, during which time the strain dynamically decreases (dynamic strain) from 6.8 s to 8 s, and the sensor's current response also dynamically decreases until it returns to its initial value. This demonstrates that the sensor proposed in this embodiment provides sensing current output under both static and dynamic strain conditions, enabling accurate detection of both static and dynamic strain.

[0043] The static / dynamic strain detection capability of the electrochemically self-powered static / dynamic tensile strain sensor was verified through a finger bending experiment. Specifically: when the finger is straight, the sensor's current response is 0; as the finger is gradually bent, the sensor begins to show a significant current response; when the finger is fully bent, the sensor's current response increases to its maximum value; while keeping the finger bent, the sensor's current response stabilizes to its maximum value; as the finger is gradually straightened, the sensor's current response gradually decreases; until the finger is fully straightened, the sensor's current response returns to 0; repeating the above bending-straightening process yields the following results: Figure 9 The real-time current response curve shown indicates that the sensor has static / dynamic strain detection capabilities.

[0044] The static strain detection in this embodiment can be applied to fields such as structural deformation monitoring of buildings (bridges, houses, etc.), robot posture perception, and aircraft posture perception, while the dynamic strain detection can be applied to fields such as human pulse, voice monitoring, and respiratory frequency.

[0045] The above embodiments are only for illustrating the principles and advantages of the present invention, and are not intended to limit the present invention. They are only for helping to understand the principles of the present invention. The scope of protection of the present invention is not limited to the above configurations and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the disclosed technology without departing from the essence of the present invention, but they are still within the scope of protection of the present invention.

Claims

1. An electrochemically self-powered static and dynamic tensile strain sensor, characterized in that, The device includes a latex tube, an elastic wire passing through the latex tube, and two electrodes with different reactivity fixed at the ends of the elastic wire and the latex tube, respectively. The elastic wire is coated with a sensitive material salt solution, causing an oxidation-reduction reaction at the two electrodes to output a sensing voltage or current, thus achieving self-powered operation. By stretching the elastic wire and the latex tube, the distance between the conductive materials is increased, leading to an increase in the internal resistance of the sensor, reducing the sensing current output, and achieving strain sensing. The sensitive material salt solution is a conductive material salt solution, specifically one of the following: carbon nanotube and lithium chloride solution, carbon black and lithium chloride solution, MXene and lithium chloride solution, graphene and lithium chloride solution, carbon nanotube and sodium chloride solution, carbon black and sodium chloride solution, MXene and sodium chloride solution, and graphene and sodium chloride solution.

2. The electrochemically self-powered static and dynamic tensile strain sensor according to claim 1, characterized in that, The elastic thread is made of polyester or nylon.

3. The electrochemically self-powered static and dynamic tensile strain sensor according to claim 1, characterized in that, The number of elastic wires is 1 to 10. Increasing the number of elastic wires increases the sensing current output.

4. The electrochemically self-powered static and dynamic tensile strain sensor according to claim 1, characterized in that, The concentration of the conductive material in the conductive material salt solution is 1~10 wt%, and the concentration of the salt is 0.5~2.0 mol / L.

5. The electrochemically self-powered static and dynamic tensile strain sensor according to claim 1, characterized in that, The elastic wires are immersed in a sensitive material salt solution for 5-15 minutes.

6. The electrochemically self-powered static and dynamic tensile strain sensor according to claim 1, characterized in that, The two electrodes with different reactivity are one of the following: copper-aluminum electrode, copper-zinc electrode, copper-silver electrode, carbon-graphite and manganese dioxide electrode, and zinc-manganese and graphite electrode.

7. The electrochemically self-powered static and dynamic tensile strain sensor according to claim 1, characterized in that, The electrochemically self-powered static and dynamic tensile strain sensors have sensing current outputs under both static and dynamic strain conditions.

8. The method for preparing the electrochemically self-powered static and dynamic tensile strain sensor according to claim 1, characterized in that, Includes the following steps: (1) Immerse the elastic cord in a salt solution of sensitive material for 5-15 minutes; (2) Pass the elastic cord through the latex tube; (3) Attach two electrodes with different reactivity to the elastic wire and the latex tube respectively.

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