Power generation device, self-operated flood sensor

Abstract

To obtain a power generation device that generates electricity autonomously without using an external power source. [Solution] The power generation device according to the present disclosure is a power generation device that generates electricity when immersed in water, and comprises a substrate, an anode formed on the substrate containing a liquid metal, and a cathode formed on the substrate containing a conductive polymer.

Description

[Technical Field]

[0001] This disclosure relates to a power generation device that generates electricity when submerged in water, and a self-driving submersion sensor using the same. [Background technology]

[0002] In recent years, due to the effects of climate change, temperatures have been on the rise, and the number of heavy rainfall events per year has increased. At the same time, rivers have overflowed, causing floods and other water-related damage. Patent Document 1 discloses a simple and low-cost flood sensor for quickly detecting and warning of flooding in a wider range of locations (Claim 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2021-196185 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, the immersion sensor described in Patent Document 1 requires a separate power supply circuit 21 to supply power to the immersion sensor 40.

[0005] This disclosure was made to solve the aforementioned problems and aims to provide a power generation device that generates electricity autonomously without using an external power source. By using such a power generation device, it becomes possible to construct a self-driving immersion sensor. [Means for solving the problem]

[0006] [1] It is a power generation device that generates electricity when submerged in water. circuit board and The substrate has an anode containing liquid metal formed on it, The substrate comprises a cathode containing a conductive polymer, Power generation device. [2] The aforementioned liquid metal includes a gallium-indium eutectic, The conductive polymer includes PEDOT:PSS. The power generation device described in [1] above. [3] The substrate comprises thermoplastic polyurethane or polyimide. The power generation device described in [1] or [2] above. [4] The substrate and the liquid metal further comprise an oxidized liquid metal, A power generation device according to any one of the above [1] to [3]. [5] A power generation device as described in any one of the above [1] to [4], The system comprises a wireless transmission device connected to the aforementioned power generation device and operated by the power generated by the aforementioned power generation device, Self-operated flood sensor. [Effects of the Invention]

[0007] This disclosure makes it possible to obtain a power generation device that generates electricity autonomously without using an external power source. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram showing the power generation device 1 according to the first embodiment connected to the wireless transmission device 15. [Figure 2] Figures 2(A) and 2(B) are graphs showing the measurement results regarding the immersion potential of EGaIn. [Figure 3] Figures 3(A) and 3(B) are graphs showing the measurement results regarding the anodic polarization of EGaIn. [Figure 4] Figures 4(A) and 4(B) are graphs showing the measurement results regarding the output when EGaIn and PEDOT:PSS are used as electrodes. [Figure 5]FIGS. 5(A) and 5(B) are graphs showing measurement results relating to output when EGaIn and PEDOT:PSS are used for electrodes. [Figure 6] It is a diagram showing an example of an electrode design. [Figure 7] It is a diagram showing an example of electrode sizes. Description of Embodiments

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each drawing, the same or corresponding portions are denoted by the same or similar reference numerals, and redundant description is omitted. Furthermore, the present invention is not limited to the following embodiments. In the present specification, numerical ranges indicated using "~" include the numerical values described before and after "~" as the minimum value and maximum value, respectively. In addition, in the present specification, when referring to both an anode and a cathode, the expression "electrode" may be used for convenience.

[0010] [Power generation device] A power generation device 1 according to a first embodiment of the present disclosure will be described with reference to FIG. 1. The power generation device 1 includes a substrate 11, an anode 12 formed on the substrate and containing a liquid metal, and a cathode 13 formed on the substrate and containing a conductive polymer. The power generation device 1, in which the anode 12 and the cathode 13 are connected by a conductive wire for passing current, has a characteristic that current flows (power is generated) when the device is immersed in water. As described above, the power generation device 1 does not include an electrolytic solution, and generates power when immersed in liquid from the outside.

[0011] The liquid for immersing the anode and the cathode (i.e., the electrodes) is not particularly limited as long as it is a solution having electrical conductivity, that is, a liquid that acts as an electrolytic solution. For example, the liquid may be rainwater, river flood water, seawater, groundwater, sewage or wastewater that causes inundation (or flooding) occurring during disasters. As described above, the power generation device of the present disclosure can be used as a power generation device for a water immersion sensor that notifies the occurrence of water immersion.

[0012] [substrate] The substrate is not particularly limited as long as it functions as a support for the electrodes, and commonly used materials can be used. For example, thermoplastic polyurethane, polyimide, or ITO glass may be used. Furthermore, stretchable substrates such as "elastomer" type stretch materials such as thermoplastic urethane elastomers, hydrogenated styrene thermoplastic elastomers, and thermoplastic acrylic elastomers, or rubber-type materials in general, are preferred because they can be attached to utility poles or poles near rivers, thus reducing restrictions on installation location. Uncoated materials are particularly preferred because they have excellent printability.

[0013] [anode] Examples of materials that can form the anode include gallium-indium eutectic, gallium-indium-tin eutectic, gallium only, indium only, rubidium, bismuth, magnesium, aluminum, zinc, iron, nickel, tin, and lead. In particular, anodes formed from liquid metal are preferred because they can follow the expansion and contraction of the expandable substrate.

[0014] As an example of a liquid metal, gallium-indium eutectic is described. Gallium-indium eutectic has low toxicity, high conductivity, deformability, high elasticity, and self-healing properties, and its viscosity increases when oxidized. Gallium-indium eutectic (EGaIn) has excellent electromechanical properties. Furthermore, oxidized gallium-indium eutectic (o-EGaIn) has high printability on various substrates. Gallium-indium eutectic may have a melting point of 15.7°C (Ga: 29.8°C, In: 157°C). The composition of gallium-indium eutectic can be freely varied, with weight ratios of Ga:In = 1:1 to 5:1 being possible. For example, the weight ratio may be Ga:In = 70.0 to 85.0:30.0 to 15.0. The weight ratio may also be Ga:In = 75.5:24.5, Ga:In = 74.5:25.5, or Ga:In = 80:20.

[0015] [Cathode] The material forming the cathode may be a conductive polymer. A cathode formed of a conductive polymer is preferable because it can follow the expansion and contraction of a stretchable substrate. The conductive polymer may be, for example, PEDOT:PSS (poly(2,3-dihydrothieno-1,4-dioxin)-poly(styrene sulfonate)).

[0016] A power generation device having an anode formed of gallium-indium eutectic and a cathode formed of PEDOT:PSS is immersed in a solution that acts as electrolyzed water. As described below, an oxidation reaction of gallium occurs at the anode, and a reduction reaction of PEDOT:PSS occurs at the cathode, generating power according to the same principle as a galvanic cell. Anode Ga→Ga 3+ +3e - Cathode PEDOT x+ :PSS y- +xe - +xH + ↔PEDOT(H + ) x PSS y-

[0017] [Wiring Method] The method for wiring liquid metal on a substrate may be screen printing using a metal mask plate. Use of a metal mask plate is preferable because even for liquid metal with high surface tension, ink can be easily filled into the plate. Further, oxidizing the liquid metal increases its viscosity and improves printability. Furthermore, oxidized liquid metal and non-oxidized liquid metal have high affinity. Therefore, wiring is facilitated and preferable when performed by a method in which oxidized liquid metal is first wired on a substrate, and non-oxidized liquid metal is placed thereon. The method for wiring a conductive polymer on a substrate can also be performed by screen printing in the same manner. The positions at which the anode and cathode are arranged on the substrate are not particularly limited. The anode and the cathode may be formed on the same substrate, or the anode and the cathode may be formed on different substrates respectively. The sizes and shapes of the anode and the cathode are also not particularly limited.

[0018] [Self-operated flood sensor] Referring to Figure 1, a self-driving flood sensor 2 according to a second embodiment of this disclosure will be described. The self-driving flood sensor 2 comprises a power generation device 1 according to the first embodiment and a wireless transmission device 15 connected to the power generation device by a conductor 14 and operated by the power generated by the power generation device 1. With this configuration, if there is no flooding at all or if the water level due to flooding is only slightly high, the power generation device 1 does not come into contact with water (does not generate power), and no current flows between the anode 12 and the cathode 13 (between electrodes), so the wireless transmission device 15 does not operate. In other words, it can be seen that flooding above a predetermined water level has not occurred. On the other hand, when the power generation device 1 comes into contact with water due to flooding, the power generation device 1 generates power, a current flows between the anode 12 and the cathode 13 (between electrodes), and the wireless transmission device 15 operates. In other words, it is possible to detect that flooding above a predetermined water level has occurred.

[0019] [Wireless transmission device] A wireless transmission device may generate radio waves (wireless signals) through its internal circuitry when power is supplied, and radiate these radio waves into the surrounding environment through an antenna. The radio waves transmitted by the wireless transmission device may be received by external devices such as smartphones, tablets, personal computers, or other digital devices.

[0020] For example, a wireless transmission device may be configured to output a signal from a wireless transmission device that operates at a constant transmission interval according to the output of a battery, such that it outputs a signal when a certain amount of energy is stored in the capacitor of the wireless transmission device, and the time of reception may be displayed on the smartphone screen. In this case, while the power generation device is immersed, energy storage and transmission are repeated. By calculating the transmission interval from the transmission time displayed on the smartphone and substituting it into the following equation (1), the transmission frequency can be obtained. Transmission frequency (s -1 ) = 1 / transmission interval (s) (1)

[0021] As described above, in the self-driving flood sensor of this disclosure, when the power generation device is submerged, an output is generated, which drives the wireless transmission device, and the transmission from the wireless transmission device can be obtained remotely, thereby enabling the detection of flooding. Therefore, by attaching the self-driving flood sensor of this disclosure, which does not require an external power supply, to utility poles or other poles near rivers, the flooding situation can be monitored remotely during floods. Furthermore, if the power generation device is expandable, it can adapt to various surface shapes, offering excellent convenience as it can be installed in various locations. [Examples]

[0022] The present disclosure will be further explained by the following examples. However, the present disclosure is not limited to these examples and can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art.

[0023] [Preparation of liquid metal] Gallium-indium eutectic (EGaIn) as a liquid metal and oxidized gallium-indium eutectic (o-EGaIn) were prepared using the method described below. Subsequently, wiring of the liquid metal was performed by manual printing using a metal mask. (1) Gallium was heated to 70°C until it became liquid. (2) Gallium and indium were mixed in a weight ratio Ga:In = 75.5:24.5. (3) The mixture was stirred at 150°C for 2 hours under a nitrogen atmosphere. (4) A gallium-indium eutectic (EGaIn) was obtained. (5) 30 g of the obtained EGaIn was weighed out. (5) With the lid of the vial open, the mixture was stirred at 2000 rpm for 15 minutes using a foam remover. (6) An oxidized gallium-indium eutectic (o-EGaIn) was obtained.

[0024] [Measurement of immersion potential of liquid metals] Immersion potential measurements were performed under the following conditions until the potential stabilized. An oxidized liquid metal (o-EGaIn) was applied to a polyimide substrate, and then an unoxidized liquid metal (EGaIn) was applied on top of it to create the working electrode (WE), and measurements were taken. ·Measurement method: open circuit potential ·Working electrode (WE): liquid metal • Opposite pole (CE): Platinum wire • Reference pole (RE): Commercially available reference pole ·Solution: 0.1M Na2SO4aq, 0.1M NaClaq ·Measuring equipment: HZ-7000 (manufactured by Hokuto Denko)

[0025] The measurement results are shown in Figures 2(A) and 2(B). When each electrode was immersed in 0.1 M sodium sulfate, the immersion potential was -0.506 V vs. SSE (Figure 2(A)). When each electrode was immersed in 0.1 M sodium chloride solution, the immersion potential was -0.621 V vs. SSE (Figure 2(B)).

[0026] [Measurement of anodic polarization of liquid metals] The anodic polarization of liquid metal was measured under the following conditions. The scanning range was from immersion potential to 0.2V. Oxidized liquid metal (o-EGaIn) was coated onto a polyimide substrate, and then unoxidized liquid metal (EGaIn) was coated on top to create the working electrode, and the measurement was performed. ·Measurement method: LSV (Linear Sweep Voltammetry) • Scanning speed: 10mV / s ·Working electrode (WE):EGaIn ·Electrode area: 5cm 2 • Reference pole (RE): Commercially available reference pole • Opposite pole (CE): Platinum wire • Scanning range: From immersion potential to 0.2V ·Measuring equipment: HZ-7000 (manufactured by Hokuto Denko) ·Solution: 0.1M Na2SO4aq, 0.1M NaClaq

[0027] The measurement results are shown in Figures 3(A) and 3(B). A higher current density was obtained when using a 0.1 M NaCl solution. Based on the results of the immersion potential measurement and anodic polarization measurement, it is considered that using a NaCl solution yields better results when a liquid metal is used as the anode material.

[0028] [Evaluation of liquid metal and PEDOT:PSS output] Under the measurement conditions described below, the output was evaluated by immersing a liquid metal as the anode and a PEDOT:PSS as the cathode in a solution. PEDOT:PSS ink was used for the PEDOT:PSS. For the liquid metal, an oxidized liquid metal (o-EGaIn) was applied, followed by an unoxidized liquid metal (EGaIn) coating for measurement. • Starting potential: Open-circuit electromotive force ·Electrode area: 5cm 2 • Anode: Liquid metal Cathode: PEDOT: PSS Ink (Orgacon TM EL-P-5015, PEDOT:PSS, Poly(2,3-dihydrothieno-1,4-dioxin)-Poly(styrene sulfonate)) ·Solution: 0.1M Na2SO4aq, 0.1M NaClaq • Scanning speed: 10mV / s

[0029] Figures 4(A) and 4(B) are graphs showing the results when PEDOT:PSS was applied to an ITO glass substrate and liquid metal to a polyimide substrate. In Example 1, a 0.1 M sodium sulfate aqueous solution was used. The maximum power density was 6.17 μW per unit area. In Example 2, a 0.1 M sodium chloride aqueous solution was used. The maximum power density was 12.2 μW per unit area. From these results, it was confirmed that power could be obtained by immersing PEDOT:PSS and liquid metal, and that it could be used as a power generation device for immersion sensors. Furthermore, a higher power output was obtained when using a 0.1 M NaCl solution. [Table 1]

[0030] Figures 5(A) and 5(B) show that both PEDOT:PSS and liquid metal are on a stretchable film substrate (polyurethane film, REACTIS TM This graph shows the results when applied to #100-STR1 (manufactured by Toray). In Example 3, a 0.1 M sodium sulfate aqueous solution was used. The maximum power density was 12.1 μW per unit area. In Example 4, a 0.1 M sodium chloride aqueous solution was used. The maximum power density was 11.8 μW per unit area. From these results, it was confirmed that sufficient power can be obtained even when using a stretchable film, and that it can be used as a power generation device for a water immersion sensor. [Table 2]

[0031] [Verification of whether wireless transmission is possible using liquid metal and PEDOT:PSS] As Example 5, we verified whether wireless transmission was possible by measuring the output obtained when liquid metal and PEDOT:PSS were immersed in a solution. The measurement conditions were the same as when the output evaluation was performed, with a 0.1M sodium chloride aqueous solution and a polyurethane film (REACTIS) as the substrate. TM Verification was performed using #100-STR1 (manufactured by Toray). As a result, when the liquid metal and PEDOT:PSS were immersed in a 0.1M NaCl solution, transmission from the wireless transmission device was confirmed. • Anode: Liquid metal Cathode: PEDOT: PSS Ink ·Solution: 0.1M NaClaq ·Electrode area: 5cm 2 • Wireless transmission device: CLEAN-Boost (manufactured by ABRIC)

[0032] [Water Infiltration Sensor Design] As shown in Figure 1, the electrodes may be fabricated on separate substrates or on a single substrate. Figure 6 shows an example of the electrode design for a water immersion sensor. In Figure 6, the electrode was fabricated by printing PEDOT:PSS as the cathode 13 as the first layer and liquid metal as the anode 12 as the second layer on a stretchable film substrate 11. The electrodes (12, 13) were each formed in a comb shape, and arranged so that the teeth of each comb interlock, but adjacent teeth do not directly contact each other. This configuration allows for quantitative evaluation of the change in output due to the immersion area. It also enables the detection of small amounts of water, such as leaks. The liquid metal in Figure 6 was printed by hand using a metal mask and a hand screen. The thickness of the metal mask was 0.2 mm. The printing conditions for PEDOT:PSS are shown below. • Clearance: 0 • Workpiece thickness: 0.13mm • Printing speed: 10mm / s • Squeegee angle: 80° • Number of layers: 3

[0033] Figure 7 shows an example of the electrode size (AD) of a water immersion sensor. [Table 3] [Explanation of Symbols]

[0034] 1. Power generation device 2 Self-propelled immersion sensor 11 circuit boards 12 Anode, Liquid Metal 13 Cathode, conductive polymer 14 Conductor 15 Wireless transmission devices

Claims

1. It is a power generation device that generates electricity when submerged in water. circuit board and The substrate has an anode containing liquid metal formed on it, The substrate comprises a cathode containing a conductive polymer, Power generation device.

2. The aforementioned liquid metal contains a gallium-indium eutectic, The conductive polymer includes PEDOT:PSS, The power generation device according to claim 1.

3. The substrate comprises thermoplastic polyurethane or polyimide. The power generation device according to claim 1 or claim 2.

4. The substrate and the liquid metal further comprise an oxidized liquid metal, The power generation device according to claim 1 or claim 2.

5. A power generation device according to claim 1 or claim 2, The system comprises a wireless transmission device connected to the aforementioned power generation device and operated by the power generated by the aforementioned power generation device, Self-operated flood sensor.

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