Method for manufacturing a pressure sensor and electrostatic-based pressure sensor using a porous-nonporous structure using the same

Abstract

The present invention discloses a method for manufacturing a pressure sensor comprising the steps of: heat-pressing a water-soluble material onto a non-cured polymer; curing the polymer; removing the water-soluble material to produce a porous structure having a plurality of pores exposed on one surface; and placing an electrode on one surface of the porous structure; and an electrostatic-based pressure sensor using a porous-non-porous structure using the same.

Description

Technology Field

[0001] The present invention relates to a method for manufacturing a pressure sensor and an electrostatic-based pressure sensor using a porous-nonporous structure utilizing the same. Background Technology

[0003] Pressure sensors are essential components in various industrial fields, and their importance is increasing, particularly in diverse application areas such as the Internet of Things (IoT), wearable devices, robotics, and medical devices. Traditional pressure sensors primarily rely on piezoelectric or capacitance-based technologies; however, these technologies generally have disadvantages, such as a lack of flexibility due to the use of rigid materials, complex manufacturing processes, and the requirement of expensive materials. Consequently, there is a growing demand to develop cost-effective alternatives that are more flexible and feature simpler manufacturing processes.

[0004] Triboelectric nanogenerators (TENGs) are a technology that generates electricity by utilizing static electricity produced during the contact and separation of different materials. They are attracting attention for their simple structure, the possibility of using various materials, and their potential in energy harvesting capabilities. However, conventional TENGs require an increased surface area to improve electricity generation efficiency, necessitating structural design to achieve this. The problem to be solved

[0006] The present invention aims to provide a flexible pressure sensor that is resistant to external shocks and increases the electricity generation efficiency of a triboelectric generator through a design that combines a porous structure and a non-porous structure. The porous structure maximizes the amount of electricity generated by increasing the contact surface area, while the non-porous structure protects the porous structure to enhance durability. Through this, the invention aims to provide a self-generating flexible pressure sensor suitable for low-power IoT sensors and wearable devices.

[0007] Meanwhile, the technical problems to be solved by the present invention are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art to which the present invention belongs from the description below. means of solving the problem

[0009] An embodiment of the present invention may provide a method for manufacturing a pressure sensor comprising the steps of: heat-pressing a water-soluble material onto a non-cured polymer; curing the polymer; removing the water-soluble material to produce a porous structure having a plurality of pores exposed on one surface; and placing an electrode on one surface of the porous structure.

[0010] In addition, embodiments of the present invention may provide a method for manufacturing a pressure sensor in which the polymer comprises at least one of polydimethylsiloxane and Ecoflex.

[0011] In addition, embodiments of the present invention may provide a method for manufacturing a pressure sensor in which the ratio of pores in the porous structure is 20% to 50% by weight.

[0012] Additionally, an embodiment of the present invention may provide a pressure sensor comprising a porous structure having a plurality of pores exposed on one surface; and an electrode disposed on one surface of the porous structure, wherein the porous structure is composed of a cured polymer.

[0013] In addition, embodiments of the present invention may provide a pressure sensor in which the polymer comprises at least one of polydimethylsiloxane and Ecoflex.

[0014] In addition, embodiments of the present invention may provide a pressure sensor in which the ratio of pores in the porous structure is 20% to 50% by weight. Effects of the invention

[0016] According to an embodiment of the present invention, it is possible to maximize electricity generation efficiency and ensure structural stability by using a triboelectric generator fabricated by mixing porous and non-porous structures.

[0017] Meanwhile, the effects obtainable from the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art to which the present invention belongs from the description below. Brief explanation of the drawing

[0019] FIG. 1 is a flowchart illustrating a method for manufacturing a pressure sensor according to one embodiment of the present invention, and FIG. 2 is an illustrative diagram for explaining a method of manufacturing a pressure sensor according to an embodiment of the present invention, and FIG. 3 is an exemplary diagram showing a pressure sensor manufactured by a method for manufacturing a pressure sensor according to an embodiment of the present invention, and FIG. 4 is an illustrative diagram for explaining the pressure driving of a pressure sensor according to an embodiment of the present invention, and FIG. 5 is an illustrative diagram for explaining the power generation drive of a pressure sensor according to one embodiment of the present invention, and Figure 6 is a graph showing the results of the characteristic evaluation of pressure sensors according to each of the embodiments and comparative examples of the present invention. Specific details for implementing the invention

[0020] Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. Embodiments of the present invention may be modified in various forms, and the scope of the present invention should not be interpreted as being limited to the embodiments below. These embodiments are provided to more fully explain the present invention to those with average knowledge in the art. Accordingly, the shapes of the elements in the drawings have been exaggerated to emphasize clearer explanations.

[0021] The configuration of the invention to clarify the solution to the problem to be solved by the present invention is described in detail with reference to the attached drawings based on preferred embodiments of the present invention. In assigning reference numbers to the components of the drawings, the same reference number is assigned to identical components even if they are located in different drawings, and it is noted in advance that components of other drawings may be cited if necessary when describing the drawings.

[0022] FIG. 1 is a flowchart illustrating a method for manufacturing a pressure sensor according to an embodiment of the present invention, FIG. 2 is an illustrative diagram illustrating a method for manufacturing a pressure sensor according to an embodiment of the present invention, FIG. 3 is an illustrative diagram illustrating a pressure sensor manufactured by a method for manufacturing a pressure sensor according to an embodiment of the present invention, FIG. 4 is an illustrative diagram illustrating pressure driving of a pressure sensor according to an embodiment of the present invention, and FIG. 5 is an illustrative diagram illustrating power generation driving of a pressure sensor according to an embodiment of the present invention.

[0023] First, referring to FIG. 1, a method for manufacturing a pressure sensor according to one embodiment of the present invention may include a heat pressing step (S10), a curing step (S20), a water-soluble substance removal step (S30), and an electrode placement step (S40).

[0024] First, the heat pressing step (S10) is a key process for forming the basis of a porous structure by combining a non-cured polymer and a water-soluble material.

[0025] First, a polymer in an uncured state is prepared and applied to a uniform thickness. The viscosity of the polymer can be adjusted so that water-soluble substances can be uniformly dispersed during the hot pressing process. Here, the polymer may include at least one of polydimethylsiloxane and Ecoflex.

[0026] In addition, water-soluble materials are prepared in the form of fine particles and uniformly sprinkled onto the polymer surface. Particle size acts as an important factor in controlling pore size.

[0027] Here, the water-soluble substance may include at least one of sugar, salt, and polyvinyl alcohol.

[0028] Meanwhile, it is preferable that the addition ratio of the water-soluble substance be 20% to 50% by weight relative to the polymer.

[0029] This can be defined as the pore ratio in the subsequently cured porous structure, and if the pore ratio in the porous structure is less than 20%, there may be a problem in that the porous structure is too small to show a significant change in electrical output, and if the pore ratio in the porous structure is more than 50%, there may be a problem in that the durability of the porous structure is weakened.

[0031] Subsequently, a set temperature and pressure are applied for a certain period of time using a heat-pressing device. During this process, the water-soluble material is compressed onto the surface, laying the foundation for the formation of a pore structure.

[0032] During the hot pressing process, the combination of temperature and pressure is a critical variable controlling polymer deformation and the fixation of water-soluble materials, requiring experimental adjustment in advance for an optimal process.

[0033] The curing step (S20) is a step for curing the polymer after the heat pressing process, which is an important process for ensuring the mechanical stability of the porous structure and fixing the desired shape. During the curing process, management is required to prevent volume shrinkage or residual stress of the polymer, and the uniformity of the pore structure must be maintained so that the water-soluble material is stably fixed.

[0034] Curing conditions vary depending on the type of polymer used, and generally, one of the following methods can be used.

[0035] Thermal Curing: A polymer is cured by heating it at a specific temperature for a set period of time. During this process, chemical cross-links are formed within the polymer, increasing mechanical strength and stability.

[0036] Thermal curing is primarily suitable for heat-insensitive materials such as PDMS, and the temperature and time used are adjusted to minimize the effect on pore formation.

[0037] UV curing: A polymer containing a UV curing agent is exposed to a UV light source to cure it within a short time (e.g., 1 to 10 minutes). UV curing is suitable when fast process speeds are required or when only specific areas need to be selectively cured.

[0038] Catalyst-based curing: A catalyst is mixed into a polymer to allow it to cure slowly at room temperature. Catalyst-based curing is suitable for applications requiring energy conservation and natural curing.

[0039] In the water-soluble material removal step (S30), water-soluble materials are removed to convert the cured polymer into a porous structure.

[0040] First, the cured polymer is immersed in water at room temperature or a suitable solvent (e.g., ethanol, isopropyl alcohol, etc.) to dissolve the water-soluble material placed on the surface of the polymer.

[0041] The immersion time varies depending on the type and amount of water-soluble material used, and it is generally preferable to perform it for 1 to 24 hours.

[0042] In addition, to increase the dissolution rate and effectively remove residues, the solution may be stirred or ultrasonic treatment (e.g., 40–60 kHz) may be applied.

[0043] During this process, the amplitude and time are controlled to prevent structural damage to the polymer.

[0044] Subsequently, washing and drying are performed. The polymer removed from the solvent is washed several times with distilled water to completely remove residual water-soluble substances and impurities.

[0045] After washing, the polymer is completely dried to remove moisture through a dryer or natural drying.

[0046] Finally, the porous structure from which the water-soluble material has been removed contains multiple pores and possesses uniform and stable porous characteristics.

[0047] The cured polymer is immersed in water or a suitable solvent to remove water-soluble substances, thereby forming a porous structure containing a plurality of pores exposed on one surface.

[0048] The electrode placement step (S40) is a key step for placing electrodes on one surface of a porous structure to collect electrical signals from a pressure sensor and precisely measure external pressure.

[0049] The electrode placement step (S40) can be carried out in the following procedure.

[0050] Electrode materials are selected using highly conductive metals (e.g., gold, silver, copper) or conductive polymers (e.g., PEDOT:PSS, CNT-based coatings).

[0051] The thickness of the electrode is designed to minimize electrical resistance while maintaining adhesion to the porous structure.

[0052] Electrode material is uniformly deposited on the surface of a porous structure using methods such as sputtering, evaporative deposition, or chemical vapor deposition (CVD).

[0053] Depending on the needs, electrodes suitable for economical and mass production can be produced by utilizing screen printing or spray coating methods using conductive ink.

[0054] Meanwhile, plasma treatment, UV exposure, or chemical surface treatment processes are applied to enhance the adhesion between the electrode and the porous structure.

[0055] This process prevents electrode delamination and increases the durability of the sensor.

[0056] Subsequently, electrical connection is performed using wire bonding, soldering, or conductive adhesive to connect the electrode to an external circuit.

[0057] Finally, the electrical characteristics and sensitivity of the porous structure with completed electrode placement are tested to verify whether they meet the design requirements.

[0058] This step aims to optimize the placement and quality of the electrodes so that the porous structure can effectively transmit static electricity generated by external pressure.

[0059] A pressure sensor as shown in Fig. 3 is completed by placing a conductive film, metal deposition, or other electrode material on one side of a porous structure.

[0060] Meanwhile, the PDMS layer and the Porous PDMS shown in Fig. 3 are a single layer, and the PDMS layer and the Porous PDMS layer may not be distinguished, as this is merely to explain the distinction between the pores formed in the Porous PDMS.

[0062] The operating principle of the pressure sensor is explained below.

[0063] First, referring to FIG. 4, the pressure sensor according to the embodiment of the present invention can be used as a sensor to detect external pressure. When a weak pressure is applied as in Region (1), relatively large shrinkage occurs in the porous structure. When shrinkage occurs to some extent as in Region (2), the degree of shrinkage changes according to the pressure. When shrinkage is almost complete as in Region (3), there is almost no change in strong pressure, so it can function as a pressure sensor.

[0064] In addition, referring to Fig. 5, when an external material comes into contact with PDMS, the magnitude of the electricity generated varies depending on the contact strength and area.

[0065] A small current is generated at low pressure, and a larger current is generated at high pressure.

[0066] During this process, the porous structure contracts and expands in response to pressure changes, altering the contact area between the electrode and the PDMS. This change in contact area directly affects the magnitude of the electrical signal.

[0067] The pores of the porous structure contract more significantly at low pressures, which causes a large change in contact area and increases signal sensitivity. Conversely, at high pressures, contraction reaches saturation, causing the change in electrical signal to become gradual.

[0068] These characteristics expand the dynamic range of the pressure sensor and enable precise measurement of various signals ranging from weak to strong pressures.

[0069] Therefore, the sensor generates a current signal based on the magnitude and rate of change of external pressure, and this signal provides data that enables real-time monitoring of pressure changes in the external environment.

[0070] Meanwhile, when an external material comes into contact with a porous structure, static electricity is generated due to the increase in the contact area. Subsequently, when the external material detaches, the electrical equilibrium is disrupted, and an electric current is generated at the electrode. Through this process, the magnitude of the current varies according to the magnitude of the external pressure, allowing for the measurement of pressure based on this.

[0072] Examples

[0073] A device with a porous structure utilizes an uncured polymer elastomer and maintains it in an incompletely cured state by applying heat of approximately 60°C (for at least 30 minutes). A water-soluble substance is applied to the surface of the polymer elastomer in this state, and then heat and pressure are applied to complete the curing of the elastomer. Subsequently, the cured polymer is immersed in water at 90°C or higher to remove the water-soluble substance. As the water-soluble substance dissolves in the water, voids the size of the particles are created within the polymer, thereby ensuring that the porous structure exists only near the surface of the polymer. A device capable of measuring pressure is fabricated by attaching electrodes, such as aluminum or copper, to the polymer. A force sensor 1053v4 is placed on the fabricated device and connected to an oscilloscope. Force is applied to the force sensor 1053v4 using a device capable of quantitatively applying force from an external source (such as a pneumatic device). At this time, the input force is quantitatively calculated based on the electrical signal generated by the force sensor 1053v4. After that, the force sensor 1053v4 is removed, and the position of the element is raised to the height of the force sensor 1053v4 to apply the same force, and the electrical output generated by the element is measured.

[0075] Comparative example

[0076] Referring to Figure 6, when comparing the electrical output generated by applying the same force to a non-porous device and a device with a porous structure, both devices exhibited linearity, but the device with the porous structure was observed to have higher sensitivity. This is because, compared to a non-porous device, a device with a porous structure can contract more than a non-porous device when the same force is applied, thanks to its porous structure. As more contraction occurs and additional static electricity is generated due to friction within the device, a higher electrical output is produced in the device with the porous structure when the same force is applied. This is because even when a weak force (0.13N) is applied, the device structure contracts more easily due to the porous structure, resulting in a higher output than that of a device with a non-porous structure, and the same trend is observed when 1.3N and 13N are applied, respectively. Furthermore, the increase in electrical output with increasing force is higher for devices with a porous structure; based on this, we demonstrate that devices with a porous structure can measure changes in force more sensitively than devices with a non-porous structure.

[0078] The above detailed description is illustrative of the present invention. Furthermore, the foregoing describes preferred embodiments of the present invention, and the present invention may be used in various other combinations, modifications, and environments. That is, modifications or alterations are possible within the scope of the concept of the invention disclosed herein, the scope equivalent to the disclosed content, and / or the scope of the art or knowledge. The described embodiments describe the best state for implementing the technical concept of the present invention, and various modifications required for specific fields of application and uses of the present invention are possible. Accordingly, the above detailed description of the invention is not intended to limit the present invention to the disclosed embodiments. Additionally, the appended claims should be interpreted as including other embodiments. Explanation of the symbols

[0080] S10: Hot pressing step S20; curing step S30; Water-soluble substance removal step S40; Electrode placement step

Claims

Claim 1 A method for manufacturing a pressure sensor comprising: a step of heat-pressing a water-soluble material onto a non-cured polymer; a step of curing the polymer; a step of removing the water-soluble material to produce a porous structure having a plurality of pores exposed on one surface; and a step of placing an electrode on one surface of the porous structure. Claim 2 A method for manufacturing a pressure sensor according to claim 1, wherein the polymer comprises at least one of polydimethylsiloxane and Ecoflex. Claim 3 A method for manufacturing a pressure sensor according to claim 1, wherein the ratio of pores in the porous structure is 20% to 50% by weight. Claim 4 A pressure sensor comprising: a porous structure including a plurality of pores exposed on one surface; and an electrode disposed on one surface of the porous structure, wherein the porous structure is composed of a cured polymer. Claim 5 In claim 4, the polymer is a pressure sensor comprising at least one of polydimethylsiloxane and Ecoflex. Claim 6 In claim 4, a pressure sensor in which the ratio of pores in the porous structure is 20% to 50% by weight.

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