Self-powered hybrid proximity sensor

Abstract

The present invention relates to a self-generating hybrid proximity sensor with an improved structure that enables precise sensing functions using a capacitive proximity sensor when power supply is available, and enables sensing functions by self-generation using a resistive proximity sensor when power supply from an external source is not available, and allows these two functions to be combined and used in various products with a simple and compact structure.

Description

Technology Field

[0001] The present invention relates to a self-generating hybrid proximity sensor, and more specifically, to a self-generating hybrid proximity sensor with an improved structure that enables precise sensing by utilizing a capacitive proximity sensor when power supply is available, and enables sensing by self-generation by utilizing a resistive proximity sensor when power supply from an external source is not available. Background Technology

[0002] Proximity sensors have established themselves as an essential technology in various industries and applications. In particular, because they can detect the presence of objects in a non-contact manner, proximity sensors play an important role in wearable devices, smart electronic skin, robot control, and human-computer interaction.

[0003] For example, robots with impaired vision can perceive their surroundings through proximity sensors. Considering these applications, the sensor needs to be flexible to be mounted on various substrates. Furthermore, there is a need to develop self-generating proximity sensors to address specific situations while eliminating the inconvenience of excessive electrical connections. Since this self-generating capability eliminates the need for inflexible power sources like batteries that pose a risk of explosion, the development of flexible, self-generating proximity sensors is essential.

[0004] Proximity sensors come in two types: capacitive and resistive. Capacitive proximity sensors detect nearby objects based on the fringing effect occurring between two electrodes; while accurate, they have the disadvantage of requiring an AC power source. Resistive proximity sensors detect nearby objects based on phenomena such as structural changes caused by the influence of the object; although they are more susceptible to environmental factors than capacitive sensors, they have the advantage of being able to operate using self-generated power as they utilize DC. Using both types of proximity sensors simultaneously in a hybrid configuration would compensate for the disadvantages of each. Prior art literature

[0005] Republic of Korea Registered Patent Publication No. 10-2065649 The problem to be solved

[0006] Accordingly, the present invention has been devised to solve the aforementioned problems. The objective of the present invention is to provide a self-generating hybrid proximity sensor that enables precise sensing functions using a capacitive proximity sensor when power supply is available, and enables sensing functions through self-generation using a resistive proximity sensor when external power supply is not possible, and can implement these multiple functions in a simplified and compact structure, and can be combined with various products. means of solving the problem

[0007] A self-generating hybrid proximity sensor according to the present invention for achieving the above objective is characterized by comprising: a capacitive sensor comprising a flexible film unit made of a synthetic resin material and a pair of electrodes formed on opposite sides of the flexible film unit to generate an electric field change according to the degree of approach of an object, so as to enable the function of the proximity sensor to be performed by self-generation even when there is no power supplied from an external source; a self-generating unit comprising graphene oxide and a material having hydrophilic functional groups, wherein the self-generating unit generates free electrons by absorbing moisture according to the change of oxygen functional groups caused by the oxidation-reduction process of graphene oxide and generates power through the movement of free electrons; and a resistive sensor that is electrically connected to the self-generating unit and is installed at a position that does not interfere with the pair of electrodes of the flexible film unit, and comprises reduced graphene oxide and a moisture-absorbing material formed on the base substrate.

[0008] The above flexible film unit is preferably made of a polyimide material.

[0009] The flexible film unit preferably comprises: a first film made of a polyimide material, wherein one of the pair of electrodes is formed using laser-induced graphene technology; and a second film made of a polyimide material, wherein the other of the pair of electrodes is formed using laser-induced graphene technology and is bonded to the first film.

[0010] It is preferable that the material having a hydrophilic functional group of the above-mentioned self-generating unit be PVA (Polyvinyl Acohol).

[0011] It is preferable that the above-mentioned self-generating unit further contain glycerol.

[0012] The self-generating unit comprising the above graphene oxide (GO), PVA, and glycerol is preferably formed into a viscous hydrogel state by mixing and dissolving PVA and glycerol in an aqueous graphene oxide solution, placing it in a mold, and then repeating the freezing and thawing process.

[0013] It is preferable that the base substrate of the above-mentioned resistive sensor be made of cellulose material.

[0014] It is preferable that the moisture-absorbing material of the above-mentioned resistive sensor be sericin.

[0015] The above-mentioned resistive sensor comprising reduced graphene oxide, sericin, and cellulose is preferably formed by mixing an aqueous solution of graphene oxide and an aqueous solution of sericin, then dip-coating cellulose into the mixed aqueous solution, and then drying it by applying heat.

[0016] It is preferable that the above self-generating unit be installed in a position that does not interfere with the pair of electrodes of the flexible film unit and the resistive sensor. Effects of the invention

[0017] The self-generating hybrid proximity sensor according to the present invention, having the configuration described above, is configured to perform a hybrid sensing function that detects the presence of an object by utilizing a highly accurate capacitive sensor when AC power is present and a resistive sensor that receives power from a self-generating unit when power is absent. Unlike conventional technology where object detection is performed selectively depending on the presence or absence of power, this enables continuous real-time object detection. Furthermore, by configuring the main components of the capacitive sensor and the self-generating unit to be provided together on a flexible film unit and allowing the flexible film unit to be combined with various products, it enables application in various industries and application fields, and achieves the effects of simplifying the configuration and slimming down the specifications. Brief explanation of the drawing

[0018] FIG. 1 is a plan view showing the structure of a self-generating hybrid proximity sensor according to an embodiment of the present invention. FIG. 2 is a conceptual diagram for explaining the sensing principle of a capacitive sensor employed in an embodiment of the present invention. FIG. 3 is a diagram illustrating an object detection function of an embodiment of the present invention. FIG. 4 is a diagram illustrating the electrode formation process of a capacitive sensor employed in one embodiment of the present invention. FIG. 5 shows the relative capacitance change value according to the distance between the capacitive sensor employed in this embodiment and the object to be detected ( A graph showing FIG. 6 is a drawing for explaining a method of manufacturing a self-generating unit employed in an embodiment of the present invention. FIG. 7 is a diagram illustrating the power generation principle of a self-generating unit employed in one embodiment of the present invention. FIG. 8 is a drawing for explaining a method of manufacturing a resistive sensor employed in an embodiment of the present invention. FIG. 9 is a diagram illustrating the sensing principle of a resistive sensor employed in an embodiment of the present invention. FIG. 10 shows the change in relative resistance according to the distance between a resistive sensor employed in an embodiment of the present invention and a nearby object ( A graph representing ). Specific details for implementing the invention

[0019] In order to clarify the understanding of the present invention in the following description, descriptions of known technologies regarding the features of the present invention will be omitted. The following embodiments are detailed descriptions to aid in understanding the present invention and are not intended to limit the scope of the rights of the present invention. Accordingly, equivalent inventions that perform the same function as the present invention will also fall within the scope of the rights of the present invention.

[0020] Furthermore, in the following description, identical identification symbols denote identical configurations, and unnecessary redundant descriptions and descriptions of known technologies are omitted. Additionally, descriptions of each embodiment of the present invention below that overlap with the description of the technology forming the background of the invention are also omitted.

[0021] Hereinafter, a self-generating hybrid proximity sensor according to an embodiment of the present invention will be described in detail with reference to the attached drawings.

[0022] FIG. 1 is a plan view showing the structure of a self-generating hybrid proximity sensor according to an embodiment of the present invention, FIG. 2 is a conceptual diagram for explaining the sensing principle of a capacitive sensor employed in an embodiment of the present invention, FIG. 3 is a diagram for explaining the object detection function of an embodiment of the present invention, FIG. 4 is a diagram for explaining the electrode formation process of a capacitive sensor employed in an embodiment of the present invention, and FIG. 5 is a relative capacitance change value according to the distance between the capacitive sensor employed in the present embodiment and the object to be detected ( FIG. 6 is a graph showing the method of manufacturing a self-generating unit employed in an embodiment of the present invention, FIG. 7 is a diagram explaining the power generation principle of a self-generating unit employed in an embodiment of the present invention, FIG. 8 is a diagram explaining the method of manufacturing a resistive sensor employed in an embodiment of the present invention, FIG. 9 is a diagram explaining the sensing principle of a resistive sensor employed in an embodiment of the present invention, and FIG. 10 is a change in relative resistance according to the distance between a resistive sensor employed in an embodiment of the present invention and a nearby object ( This is a graph representing ).

[0023] As illustrated in FIG. 1, a self-generating hybrid proximity sensor according to one embodiment of the present invention performs a precise sensing function using a capacitive sensor (1) when power supply is available, and performs a sensing function by self-generation using a self-generating unit (3) and a resistive sensor (2) when power supply from the outside is not available. It comprises a capacitive sensor (1), a self-generating unit (3), and a resistive sensor (2).

[0024] The above-described capacitive sensor (1) is formed by including a flexible film unit (11) made of a flexible synthetic resin material such as PI (polyimide) so that the present embodiment can be combined and used in various products, and by including a pair of electrodes (12) that enable a sensing function by a capacitive method.

[0025] The above pair of electrodes (12), as well illustrated in FIG. 2, are formed on opposite sides of the flexible film unit (11) to generate an electric field change according to the proximity of the object, thereby enabling the object to be detected without physical contact by a capacitive method.

[0026] The above self-generating unit (3) comprises graphene oxide and a material having hydrophilic functional groups, and generates free electrons by absorbing moisture according to the change of oxygen functional groups due to the oxidation and reduction process of graphene oxide, and generates power through the movement of free electrons. Preferably, the above self-generating unit (3) is installed at a location that does not interfere with the pair of electrodes (12) of the flexible film unit (11) and the resistive sensor (2).

[0027] The above-mentioned resistive sensor (2) is electrically connected to the above-mentioned self-generating unit (3) so that a sensing function is performed by self-generation without an external power supply, and comprises a base substrate and a material formed on the base substrate, which includes reduced graphene oxide and a moisture-absorbing material.

[0028] This resistive sensor (2) enables the detection of the presence of an object in a non-contact manner by causing a change in resistance as the hydrophilic graphene oxide and a moisture-absorbing material such as sericin absorb water and expand in volume, thereby moving the electrical conduction path further away.

[0029] A self-generating hybrid proximity sensor according to an embodiment of the present invention having the configuration described above is configured to utilize a capacitive sensor (1) with high accuracy when there is AC power, and a resistive sensor (2) that receives power from a self-generating unit (3) when there is no power, so as shown in FIG. 3, to detect the presence of an object, thereby enabling a hybrid sensing function. Unlike conventional technology where object detection is selectively performed depending on the presence or absence of power, this sensor has the advantage of being able to detect objects continuously in real time. The main components of the capacitive sensor (1) and the resistive sensor (2) are provided together on a flexible film unit (11), and the flexible film unit (11) is configured to be combined with various products for use, thereby enabling application in various industries and application fields, and has the advantage of simplifying the configuration and making the specifications slimmer.

[0030] The above flexible film unit (11) preferably includes a polyimide material and has flexibility so that bending and curvature can be smoothly performed in response to the surface shape or curvature of various products.

[0031] As clearly illustrated in FIG. 4, this embodiment is configured to smoothly form the pair of electrodes (12) on the flexible film unit (11) by applying laser-induced graphene technology.

[0032] That is, Laser-Induced Graphene (LIG) is a technology that directly generates graphene by using a high-power laser to induce localized heat treatment on a specific substrate surface. In this embodiment, a graphene electrode (12) array was fabricated on a polyimide film, which is a carbon-based material, by utilizing this technology. After forming different laser-induced graphenes in the horizontal and vertical directions on two polyimide films (first film (111), second film (112)) and attaching them, a sandwich-type lattice structure graphene electrode (12) array is formed.

[0033] The present embodiment, to which such technology is applied, has the advantage of being able to freely form graphene on a polyimide film in a desired pattern, thereby enabling the smooth formation of a pair of electrodes (12) at a low cost.

[0034] Thus, the flexible film unit (11) employed in this embodiment comprises a first film (111) made of a polyimide material formed using laser-induced graphene technology on one of the pair of electrodes (12), and a second film (112) made of a polyimide material formed using laser-induced graphene technology on the other of the pair of electrodes (12) and bonded to the first film (111).

[0035] The capacitive sensor (1) fabricated using laser-induced graphene technology has the principle of the fringing effect as shown in FIG. 2 to detect nearby objects. When power is supplied to the graphene electrode (12) formed on the upper side of the flexible film unit (11) and the graphene electrode (12) formed on the lower side, an electric field is formed between the two electrodes (12). This electric field is generated not only between the two electrodes (12) but also outward, that is, toward the object to be detected, and this is called the fringing effect. When the object to be detected enters the region of the electric field generated by the fringing effect, the electric field is disturbed, causing a change in the capacitance value of the capacitive sensor (1).

[0036] FIG. 5 shows the relative capacitance change value according to the distance between the capacitive sensor employed in this embodiment and the object to be detected ( This is a graph showing . Here represents the difference between the capacitance value of the sensor when there is no object to be detected and the capacitance value of the sensor when it is at a certain distance from the object to be detected, and represents the capacitance value of the sensor when there is no object to detect.

[0037] In this way, it can be confirmed that the relative capacitance change value of the capacitive sensor (1) changes according to distance, and based on this principle, the distance of a nearby object can be detected.

[0038] Of course, various materials can be adopted as the material having a hydrophilic functional group of the above-mentioned self-generating unit (3), but in this embodiment, PVA (Polyvinyl Acohol) was adopted.

[0039] In addition, the self-generating unit (3) is preferably formed to have flexibility and self-adhesiveness so that it can be smoothly bonded to the flexible film unit (11) and comprises glycerol together with the graphene oxide and PVA.

[0040] In this way, the self-generating unit (3) comprising graphene oxide (GO), PVA, and glycerol is preferably formed into a viscous hydrogel state by mixing PVA and glycerol in an aqueous graphene oxide solution, dissolving them, placing them in a mold, and then repeating the freezing and thawing process.

[0041] Specifically, with reference to FIG. 6, the manufacturing method of the self-generating unit (3) employed in this embodiment is described as follows.

[0042] In other words, after mixing PVA and glycerol into an aqueous solution of graphene oxide (GO), the solution is poured into a mold that has a space to accommodate the mixture. Next, a GO / PVA / glycerol hydrogel is fabricated through a process of freezing and thawing the solution. When power is supplied at a voltage of 20V in a humid environment via a power supply to both ends of the fabricated hydrogel, the graphene oxide is further oxidized at the anode, increasing the number of oxygen functional groups, while the graphene oxide is reduced at the cathode, decreasing the number of oxygen functional groups. Consequently, a gradual difference in the number of oxygen functional groups occurs between the two ends of the hydrogel.

[0043] (anode) ,

[0044] (cathode)

[0045] At the anode, water molecules attached to the surface of graphene oxide (GO) due to the humid environment generate oxygen, and this oxygen reacts with GO to create hydroxyl groups (-OH), carboxyl groups (-COOH), and epoxy groups (-O-) on the surface of GO, thereby increasing the number of oxygen functional groups on the surface of GO. At the cathode, electrons are supplied to remove the oxygen functional groups on the surface of GO, and a reduction reaction occurs, converting it into reduced graphene oxide (rGO).

[0046] Ultimately, the self-generating unit (3) containing the above graphene oxide (GO), PVA, and glycerol generates power by generating hydrogen ion flow when a humid environment is applied as in (a) of FIG. 7, and when the oxygen functional group of graphene oxide combines with water molecules, it generates hydrogen ions according to the following chemical reaction equation.

[0047] (Chemical equation for hydrogen ion generation)

[0048] Since there is a gradual difference in oxygen functional groups at both ends of this self-generating unit (3), the hydrogen ion concentration at both ends generated by the humid environment becomes different, and to resolve the difference in hydrogen ion concentration, a flow of hydrogen ions is generated by diffusion, and this flow of hydrogen ions generates power, making it possible to supply power by self-generation even when there is no external power source.

[0049] Here, the PVA is rich in hydrophilic functional groups on its surface, which helps it to bind well with water molecules in a humid environment, and the glycerol is a substance with excellent moisturizing effects, which helps maintain the moisture of the self-generating unit (3) in a hydrogel state. Figure 7 (b) shows that the magnitude of the power generated by connecting the self-generating units (3) in series increases steadily, thereby enabling the supply of a more stable and larger amount of power.

[0050] Meanwhile, with reference to FIG. 8, a method for manufacturing a resistive sensor (2) employed in this embodiment will be described.

[0051] The base substrate of the resistive sensor (2) employed in the present invention is preferably made of a cellulose material having a porous structure so that a liquid sericin solution can be formed by a dip coating method, and the moisture-absorbing material of the resistive sensor (2) is preferably sericin.

[0052] The resistive sensor (2) comprising the above-mentioned reduced graphene oxide, sericin, and cellulose is formed by mixing an aqueous solution of graphene oxide and an aqueous solution of sericin, then dip-coating cellulose into the mixed aqueous solution, and then drying it by applying heat. More specifically, the method of manufacturing the resistive sensor (2) is described in detail with reference to FIG. 8 as follows.

[0053] That is, graphene oxide (GO) / sericin is coated onto cellulose through a dip coating process in which an aqueous solution of graphene oxide (GO) and a sericin solution are mixed, and then cellulose is immersed in the mixed solution and removed. Here, the cellulose has a porous structure, so it has excellent adhesion to the aqueous solution of graphene oxide and sericin, making it suitable for dip coating.

[0054] After this dip coating process, a drying and heating process is performed, that is, heating in a chamber at 180°C for 3 hours to reduce graphene oxide (GO) to reduced graphene oxide (rGO), and finally, a resistive sensor (2) comprising reduced graphene oxide (rGO) / sericin / cellulose is produced.

[0055] In this way, the resistive sensor (2) produced has a measurement principle as shown in FIG. 9.

[0056] That is, when an object to be detected approaches the resistive sensor (2), the resistive sensor (2), which is composed of graphene oxide (rGO) / sericin / cellulose reduced by the moisture of the object, undergoes wet expansion. In particular, the sericin has a loose structure that interacts strongly with water through hydrophilic amino acids on its surface, allowing water molecules to easily penetrate into it, which is advantageous for wet expansion.

[0057] Due to this wet expansion, the distance between the reduced graphene oxide (rGO) of the resistive sensor (2) increases. Here, since the reduced graphene oxide (rGO) has excellent electrical conductivity, the relative distance between adjacent elements increases due to wet expansion, which leads to an increase in the resistance value, and through this phenomenon, the reduced graphene oxide (rGO) / sericin / cellulose structure can function as a resistive sensor (2).

[0058] FIG. 10 shows the change in relative resistance according to the distance between a resistive sensor (2) employed in one embodiment of the present invention and a nearby object ( This is a graph representing ). Here, This refers to the difference between the resistance value of the resistance sensor (2) when there is no nearby object and the resistance value of the resistance sensor (2) when there is a nearby object. This refers to the resistance value of the resistive sensor (2) when there is no nearby object. When the distance between the resistive sensor (2) and a nearby object decreases, the sericin of the resistive sensor (2) combines with water molecules due to the moisture of the object, and accordingly, the resistive sensor (2), which is composed of a reduced graphene oxide (rGO) / sericin / cellulose structure, undergoes wet expansion, and the resistance value changes as the distance between the reduced graphene oxide plates inside increases.

[0059] Although various embodiments of the present invention have been described above, these embodiments and the drawings attached to this specification merely clearly illustrate a part of the technical concept included in the present invention. It is obvious that variations and specific embodiments that can be easily deduced by a person skilled in the art within the scope of the technical concept included in the specification and drawings of the present invention are all included within the scope of the rights of the present invention. Explanation of the symbols

[0060] 1: Capacitive sensor 11: Flexible film unit 111: Film 1 112: Film 2 12: Electrode 2: Resistive sensor 3: Self-generating unit

Claims

Claim 1 delete Claim 2 delete Claim 3 A proximity sensor capable of functioning through self-generation even when no external power is supplied, comprising: a capacitive sensor including a flexible film unit made of a synthetic resin material and a pair of electrodes formed on opposite sides of the flexible film unit to generate an electric field change according to the degree of approach of an object, so as to detect an object without physical contact by a capacitive method; a self-generating unit comprising graphene oxide and a material having hydrophilic functional groups, which absorbs moisture to generate free electrons according to a change in oxygen functional groups caused by the oxidation-reduction process of graphene oxide and generates power through the movement of free electrons; and a resistive sensor electrically connected to the self-generating unit and installed at a position that does not interfere with the pair of electrodes of the flexible film unit, and comprising reduced graphene oxide and a moisture-absorbing material formed on the base substrate; wherein the flexible film unit is made of a polyimide material and one of the pair of electrodes is formed using laser-induced graphene technology, comprising a first film; A self-generating hybrid proximity sensor characterized by comprising: a first film and a second film made of polyimide material, wherein the other of the pair of electrodes is formed using laser-induced graphene technology and is bonded to the first film. Claim 4 A self-generating hybrid proximity sensor that enables the function of a proximity sensor to be performed by self-generation even when there is no externally supplied power, comprising: a flexible film unit made of a synthetic resin material and a pair of electrodes formed on opposite sides of the flexible film unit to generate a change in an electric field according to the degree of approach of an object so as to detect an object without physical contact by a capacitive method; a self-generating unit comprising graphene oxide and a material having a hydrophilic functional group, which absorbs moisture to generate free electrons according to a change in oxygen functional groups caused by the oxidation-reduction process of graphene oxide and generates power through the movement of free electrons; and a resistive sensor that is electrically connected to the self-generating unit and is installed at a position that does not interfere with the pair of electrodes of the flexible film unit, and comprises reduced graphene oxide and a moisture-absorbing material formed on the base substrate, wherein the material having a hydrophilic functional group of the self-generating unit is PVA (Polyvinyl Alcohol). Claim 5 A self-generating hybrid proximity sensor according to claim 4, characterized in that the self-generating unit further comprises glycerol. Claim 6 A self-generating hybrid proximity sensor according to claim 5, wherein the self-generating unit comprising graphene oxide (GO), PVA, and glycerol is formed into a viscous hydrogel state by mixing PVA and glycerol in an aqueous graphene oxide solution, dissolving them, placing the mixture into a mold, and then repeating the freezing and thawing process. Claim 7 A self-generating hybrid proximity sensor characterized in that, in paragraph 3, the base substrate of the resistive sensor is made of cellulose material. Claim 8 A self-generating hybrid proximity sensor that enables the function of a proximity sensor to be performed by self-generation even when there is no externally supplied power, comprising: a flexible film unit made of a synthetic resin material and a pair of electrodes formed on opposite sides of the flexible film unit to generate an electric field change according to the degree of approach of an object so as to detect an object without physical contact by a capacitive method; a self-generating unit comprising graphene oxide and a material having a hydrophilic functional group, which absorbs moisture to generate free electrons according to a change in oxygen functional groups caused by the oxidation-reduction process of graphene oxide and generates power through the movement of free electrons; and a resistive sensor that is electrically connected to the self-generating unit and is installed at a position that does not interfere with the pair of electrodes of the flexible film unit, and comprises reduced graphene oxide and a moisture-absorbing material formed on the base substrate, wherein the base substrate of the resistive sensor is made of cellulose material and the moisture-absorbing material of the resistive sensor is sericin. Claim 9 A self-generating hybrid proximity sensor according to claim 8, wherein the resistive sensor comprising the reduced graphene oxide, sericin, and cellulose is formed by mixing an aqueous solution of graphene oxide and an aqueous solution of sericin, then dip-coating cellulose into the mixed aqueous solution, and then drying by applying heat. Claim 10 A self-generating hybrid proximity sensor according to paragraph 3, wherein the self-generating unit is installed at a position that does not interfere with the pair of electrodes of the flexible film unit and the resistive sensor.

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