Pressure sensor having hierarchical dome structure and method of manufacturing same through inkjet printing process

Abstract

An embodiment of the present invention provides a hierarchical dome structure-based pressure sensor and a method for manufacturing a pressure sensor, by which the pressure sensor can be manufactured in quantity, rapidly, and economically through an inkjet printing process, the method including the steps of: preparing conductive ink; and discharging the prepared conductive ink onto a substrate to form a pressure sensor having a hierarchical dome structure shape, wherein the viscosity of the prepared conductive ink and the temperature of the substrate can be adjusted to control flow of the conductive ink.

Description

Pressure sensor having a hierarchical dome structure and its manufacturing method using an inkjet printing process

[0001] The present invention relates to a pressure sensor having a hierarchical dome structure and a method for manufacturing the same through an inkjet printing process, and more particularly, to a pressure sensor based on a hierarchical dome structure and a method for manufacturing the pressure sensor in large quantities, quickly, and economically through an inkjet printing process.

[0002] Many efforts have been made to enhance the performance of wearable devices through micro 3D structuring, which offers advantages such as increased surface area and easy structural deformability. Specifically, Zhenan Bao's research team at Stanford University in the United States developed a technology that introduced a micropyramid structure into the dielectric layer of a pressure sensor, securing superior sensitivity and short response times. Meanwhile, Gilwon Cho's research team at Pohang University of Science and Technology in Korea developed a technology that secured a wide sensing range through a hierarchical dome structure.

[0003] However, high-performance pressure sensors currently under research and development are manufactured using processes such as photolithography or 3D printing. These 3D structure fabrication methods suffer from drawbacks such as high initial equipment costs, long manufacturing times, and difficulties in manufacturing multi-arrays, making commercialization of these processes for high-performance devices a challenge.

[0004] Meanwhile, ink printing processes such as screen printing and inkjet printing have been considered feasible options for practical production and application due to their ease of fabrication. However, ink printing involves fluid flow within the droplets, such as Marangoni flow and capillary flow, which causes ink particles to move along the fluid during the droplet drying process. This phenomenon causes coffee ringing in conventional printing processes, which in turn degrades the performance of pressure sensors. Therefore, the ability to manufacture high-performance pressure sensors using high-productivity printing processes has been considered a limitation.

[0005] To address these issues, Hong Zhao's research team at Virginia Commonwealth University in the United States developed a uniformly flat monolayer deposition technique using a double-droplet printing method that deposits wet droplets containing colloidal particles onto a supporting droplet. Furthermore, Kim Hyung-soo's team at KAIST in Korea developed a process technology that temporarily seals the space where the droplets evaporate, completely eliminating the coffee ring.

[0006] However, the advancement of 3D cell structuring technology through ink printing has been minimal so far, and thus the performance of electrical sensors manufactured through ink printing has been limited to an on / off role.

[0007]

[0008] *In summary, while extensive research and development has been conducted on high-performance pressure sensors, commercialization has been hampered by limitations in the production process. To address this issue, a 3D structure manufacturing process using inkjet printing is necessary. However, no research has been conducted on the formation of 3D cell structures using inkjet printing. This process technology holds promise for applications in various industries, including wearable healthcare.

[0009] Prior patent document: Republic of Korea Patent No. 10-2237353

[0010]

[0011] The technical problem to be achieved by the present invention is to provide a manufacturing method capable of manufacturing a high-performance pressure sensor by printing, and a pressure sensor manufactured thereby, by improving the performance degradation phenomenon of a pressure sensor caused by the coffee ring phenomenon that occurs during printing of conventional general conductive ink.

[0012]

[0013] The technical problems to be solved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present invention belongs from the description below.

[0014] In order to achieve the above technical task, one embodiment of the present invention provides a method for manufacturing a pressure sensor.

[0015] The method for manufacturing a pressure sensor according to one embodiment of the present invention may include the steps of preparing conductive ink; and the step of forming a pressure sensor in the form of a hierarchical dome structure by discharging the prepared conductive ink onto a substrate, wherein the method may be characterized in that the flow of the conductive ink can be controlled by adjusting the viscosity of the prepared conductive ink and the temperature of the substrate.

[0016]

[0017] In addition, according to one embodiment of the present invention, there may be a method for manufacturing a pressure sensor, characterized in that the step of preparing the conductive ink includes the steps of: preparing a solution containing carbon black, P3HT, and chloroform; dispersing the prepared solution by ultrasonic treatment; and mixing the dispersed solution with a solution containing PDMS A and PDMS B.

[0018]

[0019] In addition, according to one embodiment of the present invention, there may be a method for manufacturing a pressure sensor, characterized in that the step of preparing a solution containing the carbon black, P3HT, and chloroform comprises controlling the viscosity of the conductive ink by controlling the amount of the chloroform.

[0020]

[0021] In addition, according to one embodiment of the present invention, there may be a method for manufacturing a pressure sensor, characterized in that the solution containing the PDMS A and PDMS B has a mass ratio of the PDMS A and PDMS B of 9:1 to 8:1.

[0022]

[0023] In addition, according to one embodiment of the present invention, there may be a method for manufacturing a pressure sensor, characterized in that the conductive ink is adjusted to have a viscosity range of 450 cP to 1400 cP.

[0024] More preferably, there may be a method for manufacturing a pressure sensor, characterized in that the conductive ink is adjusted to have a viscosity range of 600 cP to 1400 cP.

[0025] More preferably, there may be a method for manufacturing a pressure sensor, characterized in that the conductive ink is adjusted to have a viscosity range of 1000 cP to 1400 cP.

[0026]

[0027] In addition, according to one embodiment of the present invention, there may be a method for manufacturing a pressure sensor, characterized in that the temperature of the substrate is controlled to have a temperature range of 20°C to 150°C.

[0028] More preferably, there may be a method for manufacturing a pressure sensor, characterized in that the temperature of the substrate is controlled to have a temperature range of 80°C to 150°C.

[0029] More preferably, there may be a method for manufacturing a pressure sensor, characterized in that the temperature of the substrate is controlled to have a temperature range of 120°C to 150°C.

[0030]

[0031] In addition, according to one embodiment of the present invention, there may be a method for manufacturing a pressure sensor, characterized in that the hierarchical dome structure is composed of a first dome located at the center and one or more second domes located on the surface of the first dome, the diameter of the first dome located at the center is 10 mm or less, and the diameter of the second dome located on the surface of the first dome is 1.5 mm or less.

[0032]

[0033] In addition, according to one embodiment of the present invention, there may be a method for manufacturing a pressure sensor, wherein the step of forming a pressure sensor in the form of a hierarchical dome structure by discharging the conductive ink onto a substrate is characterized in that the discharging is performed within 100 ms per hierarchical dome structure.

[0034] More preferably, there may be a method for manufacturing a pressure sensor, wherein the step of forming a pressure sensor in the form of a hierarchical dome structure by discharging the conductive ink onto a substrate is characterized in that the discharging is performed within 70 ms per hierarchical dome structure.

[0035]

[0036] In addition, according to one embodiment of the present invention, there may be a method for manufacturing a pressure sensor characterized in that the flow of the conductive ink is a Marangoni flow.

[0037]

[0038] In order to achieve the above technical task, another embodiment of the present invention provides a pressure sensor.

[0039] According to one embodiment of the present invention, the pressure sensor

[0040] A pressure sensor manufactured by the above-described pressure sensor manufacturing method may be a pressure sensor characterized by having a hierarchical dome structure composed of a first dome located at the center and one or more second domes present on the surface of the first dome.

[0041]

[0042] In addition, according to one embodiment of the present invention, there may be a pressure sensor characterized in that the diameter of the first dome located at the center is 10 mm or less, and the diameter of the second dome existing on the surface of the first dome is 1.5 mm or less.

[0043]

[0044] Additionally, according to one embodiment of the present invention, there may be a pressure sensor characterized in that it can detect pressure in the entire pressure range of 0 Pa to 16000 Pa.

[0045]

[0046] Additionally, according to one embodiment of the present invention, there may be a pressure sensor characterized by having a detection speed of 50 ms or less.

[0047]

[0048] Additionally, according to one embodiment of the present invention, there may be a pressure sensor characterized in that it is capable of detecting pressure even in a stretch condition of up to 40%.

[0049] More preferably, there may be a pressure sensor characterized in that it is capable of detecting pressure even in a 20% stretch situation.

[0050] According to one embodiment of the present invention, a pressure sensor based on a hierarchical dome structure and a method for mass-producing the pressure sensor through an inkjet printing process can be provided.

[0051] According to one embodiment of the present invention, a manufacturing method capable of manufacturing a high-performance pressure sensor by printing can be provided, and a pressure sensor manufactured through the same can be provided, by improving the performance degradation of the pressure sensor caused by the coffee ring phenomenon that occurs during printing of conventional general conductive ink.

[0052] According to one embodiment of the present invention, a pressure sensor having various 3D structures (dome structure, hierarchical dome structure, coffee ring structure, flat structure) and applicable to various flexible substrates can be provided, and a method for manufacturing the same can be provided by controlling the viscosity of ink and the temperature of the substrate.

[0053] According to one embodiment of the present invention, a pressure sensor and a method for manufacturing the same can be provided that can be applied even to curved surfaces requiring elasticity and flexibility, such as a robot's finger, a human palm, etc.

[0054]

[0055] The effects of the present invention are not limited to the effects described above, and should be understood to include all effects that can be inferred from the detailed description of the present invention or the composition of the invention described in the claims.

[0056] Figure 1 is a schematic diagram showing a conductive ink manufacturing process according to one embodiment of the present invention.

[0057] Figure 2 is a schematic diagram of a manufacturing process for a hierarchical pressure sensor based on conductive ink according to one embodiment of the present invention.

[0058] FIG. 3 is a photograph showing a snapshot of a hierarchical structure-based pressure sensor manufacturing process according to one embodiment of the present invention.

[0059] FIG. 4 is a photograph showing the structuring process of ink over time in a conductive ink manufacturing process according to one embodiment of the present invention.

[0060] Figure 5 is an SEM image showing 3D structures that occur depending on the viscosity of the ink and the temperature of the substrate.

[0061] Figure 6 is a schematic diagram of a robot finger tactile sensor device to which a pressure sensor is applied according to one embodiment of the present invention.

[0062] Figure 7 is a schematic diagram of a flexible pressure measuring device according to one embodiment of the present invention.

[0063] Figure 8 shows pressure data measured through a robot finger tactile sensor to which a pressure sensor is applied according to one embodiment of the present invention.

[0064] Figure 9 illustrates an application that can utilize a pressure sensor placed on the skin according to one embodiment of the present invention.

[0065] Figure 10 shows an analysis of the shape of each representative structure. (a) is a laser scanning microscopy image of each representative structure, (b) is a graph showing the height profile of each structure, (c) is a graph showing a geometric analysis of a representative hierarchical dome structure (definition of the diameter of the large dome and the diameter of the small dome), and (d) is a graph statistically analyzing the geometric characteristics of a randomly generated hierarchical dome structure.

[0066] Figure 11 is a schematic diagram and experimental data showing the contact area according to the pressure applied to the pressure sensor according to one embodiment of the present invention.

[0067] Figure 12 is experimental data showing the change in current amount according to the pressure applied to the pressure sensor according to one embodiment of the present invention.

[0068] Figure 13 is a graph showing current values ​​and current change values ​​according to each strain in a flexible pressure measuring device according to one embodiment of the present invention.

[0069]

[0070] Hereinafter, the present invention will be described with reference to the attached drawings. However, the present invention can be implemented in various different forms and is therefore not limited to the embodiments described herein. In the drawings, irrelevant parts have been omitted for clarity of description, and similar parts have been designated with similar reference numerals throughout the specification.

[0071] Throughout the specification, when a part is said to be "connected (connected, contacted, or coupled)" to another part, this includes not only cases where it is "directly connected," but also cases where it is "indirectly connected" with another member in between. Furthermore, when a part is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0072] Throughout the specification, “dome structure” means an arch-shaped structure such as a structure forming the roof of a building, and “tiered dome structure” means a form in which the above “dome structure” is composed of multiple tiers.

[0073] The unit used to express the size of the above “dome structure” is diameter. The diameter of the above dome structure refers to the distance between the two points furthest from the center of the dome.

[0074] Throughout the specification, “pressure sensor” may be a concept including a pressure sensing unit that detects pressure.

[0075]

[0076] The terminology used herein is merely used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this specification, it should be understood that the terms "comprises" or "has" indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0077]

[0078] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.

[0079] A method for manufacturing a pressure sensor according to one embodiment of the present invention is described.

[0080]

[0081] As an example of the above embodiment, there may be a method for manufacturing a pressure sensor, including the steps of preparing conductive ink; and the step of forming a pressure sensor in the form of a hierarchical dome structure by discharging the prepared conductive ink onto a substrate, wherein the flow of the conductive ink can be controlled by adjusting the viscosity of the prepared conductive ink and the temperature of the substrate.

[0082]

[0083] As an example of the above embodiment, there may be a method for manufacturing a pressure sensor, characterized in that the step of preparing the conductive ink includes the steps of: preparing a solution containing carbon black, P3HT, and chloroform; dispersing the prepared solution by ultrasonic treatment; and mixing the dispersed solution with a solution containing PDMS A and PDMS B.

[0084]

[0085] The above hierarchical dome structure may have a first dome in the center and second domes surrounding it arranged in a hierarchical form.

[0086]

[0087] Figure 1 is a schematic diagram showing a conductive ink manufacturing process according to one embodiment of the present invention.

[0088] Figure 2 is a schematic diagram of a manufacturing process for a hierarchical pressure sensor based on conductive ink according to one embodiment of the present invention.

[0089] FIG. 3 is a photograph showing a snapshot of a hierarchical structure-based pressure sensor manufacturing process according to one embodiment of the present invention.

[0090] An example of the above embodiment is described with reference to FIGS. 1 to 3.

[0091]

[0092] Referring to Figure 1, it can be confirmed that the conductive ink can be manufactured by first preparing a mixed solution by using nano-sized carbon black, which is a conductive material, and P3HT, which acts as a dispersant, as solutes, and using chloroform as a solvent, and then dispersing the solution by ultrasonic treatment, adding 10 wt% of PDMS, and then mixing.

[0093] In the above process, the amount of chloroform determines the viscosity of the solution. This is described in detail below.

[0094]

[0095] Referring to Figure 2, the equipment used in the manufacturing process can be confirmed.

[0096] The above device is composed of a nozzle controller that controls the physical parameters of an inkjet printer, such as pneumatic pressure, discharge time, and stroke; a hot plate that applies a heat source; and an ink dispenser (including a nozzle) that discharges ink.

[0097] A pressure sensor can be manufactured by dispensing the conductive ink prepared above onto a hot plate maintained at a constant temperature.

[0098] Referring to Fig. 3, the process of actually manufacturing a pressure sensor using the above device can be confirmed.

[0099]

[0100] As an example of the above embodiment, there may be a method for manufacturing a pressure sensor, characterized in that the step of preparing a solution containing the carbon black, P3HT, and chloroform is characterized in that the viscosity of the conductive ink is controlled by controlling the amount of the chloroform.

[0101]

[0102] More specifically, when the amount of chloroform is reduced, the viscosity of the conductive ink increases, and when the amount of chloroform is increased, the viscosity of the conductive ink decreases.

[0103] For example, when the amount of chloroform is 85 wt% or more, the viscosity of the conductive ink becomes within 128 cP,

[0104] For example, when the amount of chloroform is 70 wt% or less, the viscosity of the conductive ink is 1360 cP or more.

[0105]

[0106] As an example of the above embodiment, there may be a method for manufacturing a pressure sensor, wherein the solution containing the PDMS A and PDMS B is characterized in that the PDMS A and PDMS B have a mass ratio of 9:1 to 8:1.

[0107]

[0108] As an example of the above embodiment, there may be a method for manufacturing a pressure sensor, characterized in that the conductive ink is adjusted to have a viscosity range of 450 cP to 1400 cP.

[0109] More preferably, there may be a method for manufacturing a pressure sensor, characterized in that the conductive ink is adjusted to have a viscosity range of 600 cP to 1400 cP.

[0110] More preferably, there may be a method for manufacturing a pressure sensor, characterized in that the conductive ink is adjusted to have a viscosity range of 1000 cP to 1400 cP.

[0111] As an example of the above embodiment, there may be a method for manufacturing a pressure sensor, characterized in that the temperature of the substrate is controlled to have a temperature range of 20°C to 150°C.

[0112] More preferably, there may be a method for manufacturing a pressure sensor, characterized in that the temperature of the substrate is controlled to have a temperature range of 80°C to 150°C.

[0113] More preferably, there may be a method for manufacturing a pressure sensor, characterized in that the temperature of the substrate is controlled to have a temperature range of 120°C to 150°C.

[0114]

[0115] Figure 5 is an SEM image showing 3D structures that occur depending on the viscosity of the ink and the temperature of the substrate.

[0116] An example of the above embodiment is described with reference to FIG. 5.

[0117]

[0118] Referring to Figure 5, in the image corresponding to a viscosity of 300 cP or less, it can be confirmed that a coffee ring structure is formed at a temperature of around 20°C, but as the temperature increases, a flat structure is formed.

[0119]

[0120] Additionally, in images corresponding to high viscosities of 450 cP or higher, hierarchical dome structures and even dome structures can be observed. This is because the Marangoni flow, which flows from the outer periphery of the droplet to the inner periphery, is activated as the temperature increases.

[0121] From another perspective, as viscosity increases at the same temperature, a tendency toward a coffee-ring structure, a flat structure, a hierarchical dome structure, and a dome structure can be observed. This is because the evaporation time decreases due to the decrease in solvent as viscosity increases.

[0122]

[0123] Through Fig. 5, it can be confirmed that in order to form a hierarchical dome structure according to one embodiment of the present invention, it is advantageous to form it under conditions of higher viscosity and higher temperature.

[0124]

[0125] However, if the process is performed at a temperature higher than 150℃, a problem may arise in which it is difficult to structure the structure at an accurate location due to the Leidenfrost effect.

[0126] In addition, when the viscosity condition is higher than the above 1400 cP, a problem of difficulty in discharging the ink may occur.

[0127]

[0128] As described above, the viscosity of the conductive ink and the temperature of the substrate are closely related to the structure of the pressure sensor being manufactured.

[0129] The flow of the conductive ink can be controlled by adjusting the viscosity of the prepared conductive ink and the temperature of the substrate, thereby ultimately forming a pressure sensor in the form of a hierarchical dome structure.

[0130]

[0131] As an example of the above embodiment, there may be a method for manufacturing a pressure sensor, characterized in that the hierarchical dome structure is composed of a first dome located at the center and one or more second domes located on the surface of the first dome, the diameter of the first dome located at the center is 10 mm or less, and the diameter of the second dome located on the surface of the first dome is 1.5 mm or less.

[0132]

[0133] As an example of the above embodiment, there may be a method for manufacturing a pressure sensor, wherein the step of forming a pressure sensor in the form of a hierarchical dome structure by discharging the conductive ink onto a substrate is characterized in that the discharging is performed within 100 ms per hierarchical dome structure.

[0134] More preferably, there may be a method for manufacturing a pressure sensor, wherein the step of forming a pressure sensor in the form of a hierarchical dome structure by discharging the conductive ink onto a substrate is characterized in that the discharging is performed within 70 ms per hierarchical dome structure.

[0135]

[0136] Referring to FIG. 3, the process of actually manufacturing a pressure sensor according to an example of the above embodiment can be confirmed, wherein each cell discharges within a range of 30 to 70 ms. As described above, the above manufacturing method not only has high productivity due to the fast process speed, but also demonstrates ease in manufacturing multi-array pressure sensors.

[0137]

[0138] As an example of the above embodiment, there may be a method for manufacturing a pressure sensor characterized in that the flow of the conductive ink is a Marangoni flow.

[0139]

[0140] FIG. 4 is a photograph showing the structuring process of ink over time in a conductive ink manufacturing process according to one embodiment of the present invention.

[0141] An example of the above embodiment is described with reference to FIG. 4.

[0142]

[0143] Referring to Figure 4, it can be seen that the structure is formed as the Marangoni flow progresses due to the capillary flow caused by evaporation and the temperature gradient caused by the heat source of the hot plate.

[0144]

[0145] As described above, it was confirmed that the viscosity of the conductive ink and the temperature of the substrate are closely related to the structure of the pressure sensor being manufactured, because the viscosity of the conductive ink and the temperature of the substrate affect the Marangoni flow.

[0146] By controlling the viscosity of the conductive ink prepared above and the temperature of the substrate, the Marangoni flow of the conductive ink can be controlled, thereby ultimately forming a pressure sensor in the form of the hierarchical dome structure.

[0147]

[0148] A pressure sensor according to another embodiment of the present invention is described.

[0149]

[0150] As an example of the above embodiment, there may be a pressure sensor manufactured by the above-described pressure sensor manufacturing method, characterized in that it has a hierarchical dome structure composed of a first dome located at the center and one or more second domes present on the surface of the first dome.

[0151]

[0152] As an example of the above embodiment, there may be a pressure sensor characterized in that the diameter of the first dome located at the center is 10 mm or less, and the diameter of the second dome existing on the surface of the first dome is 1.5 mm or less.

[0153]

[0154] As an example of the above embodiment, there may be a pressure sensor characterized in that it can detect pressure in the entire pressure range of 0Pa to 16000Pa.

[0155]

[0156] Compared to the performance of electrical sensors manufactured through conventional ink printing technology, which was limited to merely an on / off function, the above-described embodiment can provide a superior pressure sensor through the above-described wide and excellent detection range.

[0157]

[0158] As an example of the above embodiment, there may be a pressure sensor manufactured using the above-described pressure sensor manufacturing method, characterized by a detection speed of 50 ms or less. This corresponds to a speed sufficient to detect pressure, considering previous research on pressure sensors.

[0159]

[0160] As an example of the above embodiment, there may be a pressure sensor manufactured using the above-described pressure sensor manufacturing method, characterized in that it is capable of detecting pressure even in a state of maximum 40% elasticity.

[0161] More preferably, there may be a pressure sensor characterized in that it is capable of detecting pressure even in a 20% stretch situation.

[0162]

[0163] Figure 6 is a schematic diagram of a robot finger tactile sensor device to which a pressure sensor is applied according to one embodiment of the present invention.

[0164] Figure 7 is a schematic diagram of a flexible pressure measuring device according to one embodiment of the present invention.

[0165] Figure 8 shows pressure data measured through a robot finger tactile sensor to which a pressure sensor is applied according to one embodiment of the present invention.

[0166] Figure 9 illustrates an application that can utilize a pressure sensor placed on the skin according to one embodiment of the present invention.

[0167] An example of the above embodiment will be described with reference to FIGS. 6 to 9 above.

[0168]

[0169] Referring to FIG. 6, it can be confirmed that a pressure sensor according to an embodiment of the present invention printed on a flexible substrate can be applied to a robot finger tactile sensor application by integrating it with other signal processing module systems and covers.

[0170] In the case of a pressure sensor according to an embodiment of the present invention printed on the above flexible substrate, the substrate is designed to fit the curvature of a finger, demonstrating that pressure sensing is possible even on a curved surface.

[0171] (31) is a finger cover, and (32) functions as a sensor signal integration and processing module and a 3-axis force detection sensor. (33) functions as a support for the pressure sensor and determines the position of the lower pressure sensor. (34) is a lower pressure sensor, and its electrical resistance changes depending on its contact with the upper pressure sensor of (35), enabling pressure detection. (36) is made of a Si-based rubber material and functions as a protective layer for the finger.

[0172] A pressure sensor according to an embodiment of the present invention described above can be applied to the pressure sensors of (34) and (35).

[0173]

[0174] Referring to FIG. 8, it can be confirmed that pressure can be measured with the finger of a robot to which a pressure sensor according to one embodiment of the present invention is applied.

[0175] Figure 8 (a) shows the distribution of pressure that occurs when holding a needle, and Figure 8 (b) shows the distribution of pressure that occurs when holding a computer mouse.

[0176]

[0177] Referring to FIG. 7, a flexible pressure measurement sensor according to one embodiment of the present invention can be manufactured by discharging a conductive solution onto a flexible polymer substrate.

[0178] (41), a component of the above pressure sensor, is a PDMS bumper that allows the external pressure to be fully concentrated on the cell. (42) is a PDMS substrate on which SWCNTs, which are electrodes, are deposited, and has a wrinkled interface for elasticity. (43) is an electrode on which SWCNTs are deposited through a transfer process. (44) is a pressure-sensitive layer created by discharging conductive ink, and its 3D structure is formed differently depending on the viscosity of the ink and the temperature of the substrate. (45) is a lower electrode, and like the upper electrode, it is deposited on the lower PDMS substrate (47) through a transfer process. (46) is a spacer that initially prevents contact between the lower pressure-sensitive layer and the upper electrode layer.

[0179] The above pressure sensor can maintain its performance even in a stretched state.

[0180]

[0181] Referring to Fig. 9, in Fig. 9 (a), a pressure distribution formed in the shape of the sole of a penguin can be confirmed by placing a penguin on a pressure sensor on the palm, and in Fig. 9 (b), a pressure distribution measured by a pressure sensor on a human hand when shaking hands with a robot hand can be confirmed.

[0182]

[0183] As described above, in the case of one example of the above embodiment, since pressure can be detected even in a stretched state of up to 40%, it has the advantage of being applicable to curved surfaces such as the robot hand described above or the surface of the human body.

[0184]

[0185] Manufacturing example 1. Manufacturing of pressure sensor.

[0186]

[0187] 1. Step 1: Preparing conductive ink

[0188]

[0189] - A mixed solution is prepared by using 200 mg of nano-sized carbon black, a conductive material, and 1 mg of P3HT, which acts as a dispersant, as solutes and 4 ml of chloroform as a solvent.

[0190] - Afterwards, the solution is dispersed by ultrasonic treatment for about 30 minutes.

[0191] - Afterwards, the PDMS A and PDMS B are mixed in a mass ratio of 9:1 to 8:1 and added to the solution.

[0192] - Mix well.

[0193]

[0194] 2. Step of forming a pressure sensor in the form of a hierarchical dome structure by discharging conductive ink onto a substrate.

[0195]

[0196] - The conductive ink manufactured above is ejected onto a hot plate maintained at a temperature of 80°C. At this time, the air pressure is 120 kPa, the ejection time is 50 ms, and the stroke is 60%.

[0197]

[0198] Experimental Example 1. Structural Analysis.

[0199] Figure 10 shows an analysis of the shape of each representative structure. (a) is a laser scanning microscopy image of each representative structure, (b) is a graph showing the height profile of each structure, (c) is a graph showing a geometric analysis of a representative hierarchical dome structure (definition of the diameter of the large dome and the diameter of the small dome), and (d) is a graph statistically analyzing the geometric characteristics of a randomly generated hierarchical dome structure.

[0200] The above experimental example 1 is described with reference to Fig. 10.

[0201]

[0202] Referring to (a) of Fig. 10, the structure and shape of each representative structure can be confirmed through laser scanning microscopy of each representative structure.

[0203] Referring to (b) of Fig. 10, the height of the cross-section of each representative structure can be confirmed, and through this, the hierarchical dome structure of the pressure sensor according to one embodiment of the present invention can be interpreted as a collection of large arcs (first dome) and small circles (second dome).

[0204] Referring to (c) and (d) of Fig. 10, as a result of analyzing a total of 10 samples, it can be confirmed that the average chord of the large arc (first dome) was 2250 μm, the radius of the small circle (second dome) was 175 μm, and the number of the small circles (second domes) was 5 on average.

[0205]

[0206] Experimental Example 2. Performance analysis according to pressure.

[0207] Figure 11 is a schematic diagram and experimental data showing the contact area according to the pressure applied to the pressure sensor according to one embodiment of the present invention.

[0208] Figure 12 is experimental data showing the change in current amount according to the pressure applied to the pressure sensor according to one embodiment of the present invention.

[0209] The above experimental example 2 is described with reference to FIGS. 11 and 12.

[0210]

[0211] Referring to FIG. 11, it can be confirmed that the pressure sensor having a hierarchical dome structure according to one embodiment of the present invention has a contact area that increases more linearly with applied pressure compared to a pressure sensor having a general dome structure.

[0212] Referring to (a) of Fig. 11, when pressure is applied, in the case of the hierarchical dome structure, even if pressure is applied, the second dome located on the surface of the first dome supports the first dome, so it can be confirmed that even if pressure is applied, the contact area does not change rapidly because the contact area is located in a distributed manner.

[0213] On the other hand, in the case of a typical dome structure, it can be seen that the contact area increases rapidly as pressure is applied.

[0214] Referring to (b) of Fig. 11, the above contents can be confirmed with specific data, through which it can be confirmed that the contact area of ​​the hierarchical dome structure increases less sensitively than that of the general dome structure and increases more linearly.

[0215]

[0216] Referring to (a) of Fig. 12, in the case of the coffee ring structure, it can be confirmed that detection is difficult after 1000 Pa as saturation of the contact area occurs quickly.

[0217] Additionally, in the case of the dome structure, it was possible to detect a fine pressure of 50 Pa, but it was confirmed that detection was difficult from 1200 Pa.

[0218] On the other hand, it can be confirmed that the hierarchical dome structure according to one embodiment of the present invention can detect up to 16000 Pa.

[0219] Referring to (b) of Fig. 12, it can be confirmed that in the case of the hierarchical dome structure according to one embodiment of the present invention, the response speed is also satisfactory at approximately 50 ms.

[0220] In addition, referring to (c) of FIG. 12, it can be confirmed that in the case of a hierarchical dome structure according to one embodiment of the present invention, detection of a change in current amount significantly occurs even when dynamic pressure changes.

[0221]

[0222] Experimental Example 3. Performance analysis of the elastic pressure measurement device.

[0223] Figure 13 is a graph showing current values ​​and current change values ​​according to each strain in a flexible pressure measuring device according to one embodiment of the present invention.

[0224] The above experimental example 3 is described with reference to Fig. 13.

[0225]

[0226] Referring to FIGS. 6 to 9, a device capable of detecting pressure even in a stretchy situation can be confirmed by applying a printing process to a stretchable substrate.

[0227] Referring to FIG. 13, in the case of a pressure sensor according to one embodiment of the present invention, it can be confirmed that a satisfactory current value is shown even at a strain of 20%, and a uniform current change value (within a 10% difference) is shown even when the pressure is measured at a 20% pull state.

[0228]

[0229] The foregoing description of the present invention is for illustrative purposes only, and those skilled in the art will readily appreciate that the present invention can be readily modified into other specific forms without altering the technical spirit or essential characteristics of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. For example, each component described as a single entity may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined manner.

[0230] The scope of the present invention is indicated by the claims described below, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention.

[0231]

[0232] <Explanation of symbols>

[0233] 3: Robot finger tactile sensor

[0234] 31: Finger cover

[0235] 32: Sensor signal integration sensor and 3-axis force detection sensor

[0236] 33: Sensor support

[0237] 34: Lower pressure sensor

[0238] 35: Upper pressure sensor

[0239] 36: Si-based sensor cover (protective layer)

[0240] 4: Elastic pressure measuring device

[0241] 41: PDMS bumper

[0242] 42: PDMS substrate

[0243] 43: Stretchable electrode

[0244] 44: Pressure sensing active layer

[0245] 45: Stretchable electrode

[0246] 46: Spacer

[0247] 47: PDMS substrate

Claims

1. Step of preparing conductive ink; and A step of forming a pressure sensor in the form of a hierarchical dome structure by discharging the conductive ink prepared above onto a substrate, A pressure sensor manufacturing method characterized in that the flow of the conductive ink can be controlled by adjusting the viscosity of the prepared conductive ink and the temperature of the substrate.

2. In the first paragraph, the step of preparing the conductive ink comprises: A step of preparing a solution containing carbon black, P3HT, and chloroform; A step of dispersing the prepared solution by ultrasonic treatment; and A method for manufacturing a pressure sensor, characterized by comprising a step of mixing the above-described dispersed solution and a solution containing PDMS A and PDMS B.

3. In the second paragraph, the step of preparing a solution containing carbon black, P3HT, and chloroform comprises: A method for manufacturing a pressure sensor, characterized in that the viscosity of the conductive ink is controlled by controlling the amount of the chloroform.

4. In the second paragraph, the solution containing PDMS A and PDMS B, A method for manufacturing a pressure sensor, characterized in that the above PDMS A and PDMS B have a mass ratio of 9:1 to 8:

1.

5. A method for manufacturing a pressure sensor, characterized in that in the first paragraph, the conductive ink is adjusted to have a viscosity range of 450 cP to 1400 cP.

6. A pressure sensor manufacturing method, characterized in that in the first paragraph, the temperature of the substrate is controlled to have a temperature range of 20°C to 150°C.

7. In the first paragraph, the hierarchical dome structure, It is composed of a first dome located in the center and one or more second domes located on the surface of the first dome. The diameter of the first dome located in the center above is 10 mm or less, A pressure sensor manufacturing method characterized in that the diameter of the second dome existing on the surface of the first dome is 1.5 mm or less.

8. In the first paragraph, the step of forming a pressure sensor in the form of a hierarchical dome structure by discharging the conductive ink onto a substrate is as follows: A pressure sensor manufacturing method characterized in that the above discharge is performed within 100 ms per hierarchical dome structure.

9. A method for manufacturing a pressure sensor, characterized in that the flow of the conductive ink in the first paragraph is a Marangoni flow.

10. A pressure sensor manufactured by the manufacturing method of paragraph 1, A pressure sensor characterized by having a hierarchical dome structure composed of a first dome located at the center and one or more second domes present on the surface of the first dome.

11. In paragraph 10, The diameter of the first dome located in the center above is 10 mm or less, A pressure sensor characterized in that the diameter of the second dome existing on the surface of the first dome is 1.5 mm or less.

12. A pressure sensor according to claim 10, characterized in that the pressure sensor can detect pressure in the entire pressure range of 0 Pa to 16000 Pa.

13. A pressure sensor according to claim 10, characterized in that the pressure sensor has a detection speed of 50 ms or less.

14. A pressure sensor according to claim 10, characterized in that the pressure sensor is capable of detecting pressure even in a state of elasticity of up to 40%.

Images