KR102159453B1 - Capacitive pressure sensor and method of fabricating the same - Google Patents

Abstract

The present invention relates to a capacitive pressure sensor having a low driving voltage and a manufacturing method thereof. The capacitive pressure sensor according to one embodiment of the present invention may comprise: a first electrode layer; a dielectric layer which is disposed on the first electrode layer, comprises an ionic gel layer containing a crystalline polymer and an ionic liquid impregnated in the crystalline polymer, and has a surface roughness controlled by recrystallization of a chain of the crystalline polymer in the ionic gel layer; and a second electrode layer disposed on the dielectric layer.

Description

Capacitive pressure sensor and method of fabricating the same}

The present invention relates to sensor technology, and more particularly, to a capacitive pressure sensor and a method of manufacturing the same.

Pressure sensors have been actively studied in recent years because they have potential applications in many wearable electronic devices including soft robots, artificial electronic skins (e-skin), health monitoring and mobile displays. In order to apply the pressure sensor, particularly to wearable and/or on-body electronic devices, it is important to secure optical transparency and mechanical flexibility as well as pressure sensitivity and reliability.

In general, the pressure sensor can be classified into a piezoelectric type, a piezoelectric resistance type, and a capacitive type sensing method. Among them, the capacitive sensing type pressure sensor is based on the pressure-sensitive capacitance change of the dielectric film before and after pressure, and has the advantages of fast response time, low power operation, and simple device architecture, thereby implementing a compact circuit layout. It can be advantageous over other methods.

In general, elastomeric-based dielectrics can be combined with various micro-scale surface corrugated architectures to further improve the sensitivity of the sensor. The underlying technology for this surface corrugated architecture is a synthetic elastomer foam with a suspended structure, a thin porous film, an elastomer/SiO2 nanoparticle composite dielectric layer, an elastomer coated on a rough paper surface, and topologically fine. It is composed of an elastomer with a structured surface. However, according to this method, due to the low dielectric constant of the elastomer itself, there is a problem in that the amount of change in capacitance is small and the sensitivity in the low pressure region is low.

[Prior technical literature]
[Patent Literature]
(Patent Document 0001) Korean Patent Publication No. 10-2019-0059252 "Dielectric for pressure sensor and its manufacturing method and capacitive pressure sensor" (Publication date: 2019.05.30.)
(Patent Document 0002) Korean Patent Registration No. 10-1215919 "Capacitive pressure sensor and its manufacturing method" (announcement date: 2012.12.27.)

Accordingly, the technical problem to be solved by the present invention is to provide a capacitive pressure sensor having excellent transparency and flexibility, excellent sensitivity to a wide range of external pressures from several Pa to tens of kPa, and a low driving voltage. .

In addition, another technical problem to be solved by the present invention is to provide a method of manufacturing a high sensitivity transparent and flexible capacitive pressure sensor with a simple manufacturing process at low cost.

According to an embodiment of the present invention, a first electrode layer; An ionic gel layer disposed on the first electrode layer and comprising a crystalline polymer and an ionic liquid impregnated in the crystalline polymer, and the chain of the crystalline polymer of the ionic gel layer A dielectric layer having a surface roughness controlled by recrystallization; And a second electrode layer disposed on the dielectric layer, and a capacitive pressure sensor may be provided.

The capacitive pressure sensor may further include an air gap formed through the surface roughness between the dielectric layer and any one of the first electrode layer and the second electrode layer. The capacitive pressure sensor may further include an electric double layer (EDL) formed between an interface of the dielectric layer and any one of the first electrode layer and the second electrode layer. The surface roughness may include a micro-fibril type topology. The recrystallization of the chain of the crystalline polymer includes that the chain of the crystalline polymer is aligned parallel to the surface normal of the dielectric layer, and the crystalline polymer is formed by bending the chain. It has a platelet crystal shape, and may have a lamellar structure based on a surface normal of the dielectric layer. The root mean square (RMS) of the surface roughness may range from 0.5 nm to 500 nm. The content of the ionic liquid impregnated in the crystalline polymer may have a range of more than 0% by weight and not more than 60% by weight. The crystalline polymers are PVDF, P(VDF-TrFE), P(VDF-CTFE), P(VDF-CFE), P(VDF-HFP), P(VDF-TrFE-CTFE), P(VDF-TrFE- CFE) and P(VDF-TrFE-HFP) may be a PVDF based copolymer. The ionic liquid contains at least one of EMI-TFSA, BMIM TFSI, OMIM TFSI, EMIM TFSI, EMIM-BF4, EMIM-TCB, BMIM-TFSI, EMIM-SO4, BMIM-BF4, DMIM-BF4, and DMIM-TFSI. can do.

In one embodiment, at least one of the first electrode layer and the second electrode layer is formed on a polymer substrate, and at least one of the first electrode layer and the second electrode layer is line-patterned on the polymer substrate and Including a second graphene layer, wherein the capacitive pressure sensor comprises a plurality of crossing points between the line patterned first graphene layer and the line patterned second graphene layer It can have an array.

According to another embodiment of the present invention, the step of forming a first electrode layer; On the first electrode layer, disposed on the first electrode layer, comprising an ionic gel layer comprising a crystalline polymer and an ionic liquid impregnated in the crystalline polymer, the crystallinity of the ionic gel layer Forming a dielectric layer having a surface roughness controlled by recrystallization of a polymer chain; And forming a second electrode layer on the dielectric layer. A method of manufacturing a capacitive pressure sensor may be provided.

In an embodiment, the forming of the dielectric layer may include preparing the crystalline polymer and the ionic liquid; Mixing the crystalline polymer and the ionic liquid to form an ionic mixed solution; Coating the ionic mixed solution on the first electrode layer to form an ionic gel layer; And heat-treating the ionic gel layer to recrystallize the chain of the crystalline polymer. The temperature of the heat treatment may be higher than the melting temperature of the crystalline polymer. After the heat treatment step, it may further include adjusting the cooling rate of the ionic gel layer. The cooling rate may have a range of 5.0 °C / min to 0.1 °C / min. At least one of the first electrode layer and the second electrode layer is formed on a polymer substrate, and at least one of the first electrode layer and the second electrode layer is line patterned first and second graphene layers on the polymer substrate Including, the capacitive pressure sensor may have an arrangement of capacitor cells each defined at a plurality of intersections between the line patterned first graphene layer and the line patterned second graphene layer. .

According to an embodiment of the present invention, it includes a crystalline polymer and an ionic gel layer containing an ionic liquid impregnated in the crystalline polymer, and recrystallization of a chain of the crystalline polymer in the ionic gel layer By using the dielectric layer having the surface roughness controlled by the fire, it is possible to provide a flexible capacitive pressure sensor having excellent sensitivity to a wide range of external pressures from several Pa to several tens of kPa and having a low driving voltage.

In addition, by performing recrystallization of the crystalline polymer by controlling the heat treatment and cooling rate without using a mold (mold free), it is possible to provide a simple method of manufacturing a capacitive pressure sensor at low cost.

1A is an exploded perspective view showing a capacitive pressure sensor according to an embodiment of the present invention, FIG. 1B is a cross-sectional view of a capacitive pressure sensor, and FIG. 1C is a capacitive pressure sensor according to an embodiment of the present invention. It is a perspective view of a dielectric layer having a lamellar structure of a sensor.
2A is a view for explaining a method of manufacturing a capacitive pressure sensor according to an embodiment of the present invention, and FIG. 2B is an image showing the transparency and flexibility of the capacitive pressure sensor according to an embodiment of the present invention. , Figure 2c is a graph showing the transparency of the capacitive pressure sensor according to an embodiment of the present invention.
3A to 3C are views for explaining a polymer crystal of a dielectric layer of a capacitive pressure sensor according to a heat treatment temperature according to an embodiment of the present invention, and FIGS. 3D to 3F are 2 of the dielectric layers of FIGS. 3A to 3C. A diagram showing a dimensional grazing incident X-ray diffraction (GIXD) pattern.
4A to 4C and FIGS. 4E to 4G are AFM (atomic force microscopy) images of a dielectric layer of a capacitive pressure sensor according to a heat treatment temperature according to an embodiment of the present invention, and FIG. 4D is an embodiment of the present invention. It is a scanning electron microscopy (SEM) image of the dielectric layer of the capacitive pressure sensor according to the heat treatment temperature according to.
5 is a graph showing a root mean square (RMS) roughness of a capacitive pressure sensor according to a heat treatment temperature and a cooling rate according to an embodiment of the present invention.
6A is a schematic diagram of a pressure sensing system according to an embodiment of the present invention, FIG. 6B is a graph showing a change in capacitance according to a content of an ionic liquid, and FIG. 6C is a graph showing a change in capacitance according to a cooling rate. , FIG. 6D is a graph showing the sensitivity of the capacitive pressure sensor according to the cooling rate, FIG. 6E is a graph showing the change in capacitance according to the change in the pressure load at 500 Hz, and FIG. 6F is a specific pressure measured at 100 kHz. It is a graph showing the change rate according to the time change of the capacitance value, and FIG. 6G is a graph showing the change in capacitance of the capacitive pressure sensor according to the number of repetitions of pressure loading and unloading.
7A is a graph showing the change in capacitance of the capacitive pressure sensor by aluminum pellets, FIG. 7B is a graph showing the change in capacitance of the capacitive pressure sensor by soft finger touch, and FIG. 7C is It is a graph showing the change in capacitance of the capacitive pressure sensor, and FIG. 7C is a graph showing the change in the capacitance of the capacitive pressure sensor according to bending repetition.
FIG. 8A is a schematic diagram of a 12×12 pressure sensor matrix, FIG. 8B is an image photograph of a pressure sensor array made of patterned graphene and a dielectric layer, and FIG. 8C is a diagram showing an equivalent circuit of a 12×12 pressure sensor matrix. , FIG. 8D is a graph showing the magnitude of capacitance change by multi-touch.
9A is an AFM (atomic force microscopy) height profile of the dielectric layer of the capacitive pressure sensor according to the heat treatment temperature according to an embodiment of the present invention, and FIG. 9B is an AFM of the dielectric layer of the capacitive pressure sensor according to the heat treatment temperature. atomic force microscopy) 3D height image, and FIG. 9C is a graph showing the difference in height of the surface roughness of the dielectric layer of the capacitive pressure sensor according to the heat treatment temperature.
10A to 10C are graphs showing changes in capacitance of a capacitive pressure sensor according to pressure loading and pressure unloading.
FIG. 11A is a graph showing a change in capacitance of a capacitive pressure sensor according to a frequency change according to a no-load pressure, and FIG. 11B is a capacitive pressure sensor according to a frequency change in a state in which an air gap is not present by depositing a metal electrode. It is a graph showing the change in capacitance of.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The embodiments of the present invention are provided to more completely describe the present invention to those of ordinary skill in the art, and the following examples may be modified in various other forms, and the scope of the present invention is as follows. It is not limited to the examples. Rather, these embodiments are provided to make the present disclosure more faithful and complete, and to completely convey the spirit of the present invention to those skilled in the art.

In the drawings, the same reference numerals refer to the same elements. Also, as used herein, the term “and/or” includes any and all combinations of one or more of the corresponding listed items.

The terms used in this specification are used to describe examples, and are not intended to limit the scope of the present invention. In addition, even if it is described in the singular in this specification, a plurality of forms may be included unless the context clearly indicates the singular. In addition, the terms "comprise" and/or "comprising" as used herein specify the presence of the mentioned shapes, numbers, steps, actions, members, elements and/or groups thereof. It does not exclude the presence or addition of other shapes, numbers, movements, members, elements and/or groups.

Reference to a layer formed “on” a substrate or other layer herein refers to a layer formed directly on the substrate or other layer, or formed on an intermediate layer or intermediate layers formed on the substrate or other layer. It may also refer to a layer. Further, for those skilled in the art, a structure or shape arranged “adjacent” to another shape may have a portion disposed below or overlapping with the adjacent shape.

In this specification, "below", "above", "upper", "lower", "horizontal" or "vertical" Relative terms such as, as shown on the drawings, may be used to describe the relationship between one component member, layer, or region with another component member, layer, or region. It is to be understood that these terms encompass not only the orientation indicated in the figures, but also other orientations of the device.

In the following, embodiments of the present invention will be described with reference to cross-sectional views schematically showing ideal embodiments (and intermediate structures) of the present invention. In these drawings, for example, the size and shape of the members may be exaggerated for convenience and clarity of description, and in actual implementation, variations of the illustrated shape may be expected. Accordingly, the embodiments of the present invention should not be construed as being limited to the specific shape of the region shown in this specification. In addition, reference numerals of members in the drawings refer to the same members throughout the drawings.

1A is an exploded perspective view showing a capacitive pressure sensor 10 according to an embodiment of the present invention, FIG. 1B is a cross-sectional view of a capacitive pressure sensor, and FIG. 1C is an electrostatic capacity type pressure sensor according to an embodiment of the present invention. A perspective view of a dielectric layer DL having a lamellar structure of a capacitive pressure sensor.

1A and 1B, the capacitive pressure sensor 10 is disposed on the first electrode layer E1 and the first electrode layer E1, and includes a crystalline polymer and an ionic liquid impregnated in the crystalline polymer. A dielectric layer (DL) and a dielectric layer (DL) comprising an ionic gel layer containing (PI, NI) and having a surface roughness controlled by recrystallization of the chain (PC) of the crystalline polymer of the ionic gel layer. ) May include a second electrode layer E2 disposed on it. The capacitive pressure sensor 10 may include an air gap GA formed through the surface roughness between the first electrode layer E1 and the dielectric layer DL. By forming the air gap GA between the first electrode layer E1 and the dielectric layer DL, it is possible to improve the viscoelastic properties of the crystalline polymer and increase the amount of strain change. Although not shown, optionally, an air gap GA formed through the surface roughness between the second electrode layer E2 and the dielectric layer DL may be included. The ionic liquid is dispersed between the pores of the crystalline polymer and trapped in the dielectric layer DL, so that the dielectric layer DL may have a stable ionic gel type. In one embodiment, the crystalline polymer includes a crystalline region and an amorphous region, and the ionic liquid may be disposed in the amorphous region of the crystalline polymer.

In one embodiment, the capacitive pressure sensor 10 is an electric double layer formed between the interface between the first electrode layer E1 and the dielectric layer DL and the interface between the second electrode layer E2 and the dielectric layer DL. : EDL) can be included. The electric double layer includes a whole or partial region of the first surface of the first electrode layer E1 adjacent to the first surface of the dielectric layer DL, and the second electrode layer E1 adjacent to the second surface of the dielectric layer DL. It may be formed over all or part of the two sides. Specifically, a positive ion is formed between the interface between the first electrode layer E1 and the dielectric layer DL, and a negative ion is formed between the interface between the second electrode layer E2 and the dielectric layer DL, or the first electrode layer Anions may be formed between the interface between (E1) and the dielectric layer DL, and cations may be formed between the interface between the second electrode layer E2 and the dielectric layer DL. The electric double layer is formed between the interface between the first electrode layer E1 and the dielectric layer DL when a voltage is applied to the sensor element, and the formed electric double layer may increase the bonding area of the electric double layer in proportion to the applied pressure. have. On the other hand, even when a pressure is applied to the sensor element, if no voltage is applied, the electric double layer is not formed, and cations/anions of the ionic liquid may exist randomly.

The use of an ionic liquid having a nonvolatile cation (PI) and a charge-delocalized anion (NI) in the electric double layer (EDL) improves pressure sensitivity having a high dielectric constant and physicochemical stability. I can make it.

In an embodiment of the present invention, the surface roughness may include a topology in the form of micro-fibrils. The microfibrous topology may be formed by controlling the heat treatment temperature and cooling rate of the ionic gel layer in the manufacturing method of the capacitive pressure sensor 10 to be described later. The root mean square (RMS) of the surface roughness ranges from 0.5 nm to 500 nm. When the square average of the surface roughness is 0.5 nm or less, when the applied pressure is removed, the capacitance of the capacitive pressure sensor 10 is not restored to a low initial state, and when it is in the range of 500 nm or more, light is not completely transmitted. Without scattering, the transparency of the device may be significantly reduced.

The content of the ionic liquid impregnated in the crystalline polymer has a range of more than 0% by weight and not more than 60% by weight. When the content of the ionic liquid is 0% by weight, since the electric double layer (EDL) is not formed, it is difficult to increase the width of change in the capacitance of the capacitive pressure sensor 10, and for a wide range of external pressures. It cannot have excellent sensitivity performance, and when the content of the ionic liquid exceeds 60% by weight, the dielectric layer DL has high viscoelasticity and high adhesiveness, and the pressure sensing speed and recovery speed may be slowed. . The crystallinity of the crystalline polymer may be 50% or more. When the crystallinity of the crystalline polymer is less than 50%, the surface roughness for high sensitivity to a wide range of external pressures of the capacitive pressure sensor 10 may not be formed.

Referring to FIG. 1C, the chain PC of the crystalline polymer has a platelet crystal shape by a folded shape, and may have a lamellar structure based on the surface normal N of the dielectric layer DL.

The orientation of the lamellar structure may be determined according to the heat treatment temperature in the heat treatment step to be described later. Specifically, when not heat treated (as cast) or heat treated at 115°C, the folded polymer chain has a crystal form in the form of a needle-like fibril, and the lamellar structure is the surface normal (N) of the dielectric layer (DL). ) Can have a shape arranged in a direction perpendicular to. In addition, when heat treatment is performed at a temperature higher than the melting temperature of the crystalline polymer (eg, 185° C.), the folded polymer chains PC may be aligned parallel to the surface normal N of the dielectric layer DL. In addition, the lamellar structure may have a double layered form.

In one embodiment, the recrystallization of the chain (PC) of the crystalline polymer may include that the folded polymer chain (PC) is aligned parallel to the surface normal (N) of the dielectric layer (DL), and melting It may be in the form of crystals crystallized from the state.

In one embodiment of the present invention, the crystalline polymer is PVDF, P(VDF-TrFE), P(VDF-CTFE), P(VDF-CFE), P(VDF-HFP), P(VDF-TrFE-CTFE) ), P(VDF-TrFE-CFE), and P(VDF-TrFE-HFP), but may include a PVDF series polymer, but is not limited thereto. For example, a fluorinated copolymer having a high dielectric constant and viscoelastic behavior may be used as the crystalline polymer.

The ionic liquid contains a cation (PI) and an anion (NI), and the cation (PI) is Ammonium, Imidazolium, Oxazolium, Piperidinium, Pyrazinium, Pyrazolium, Pyridazinium, Pyridinium, Pyrimidinium, Pyrrolidinium, Pyrrolinium, Pyrrolium, Thriazolium, Triazolium is selected from the group consisting of anionic (NI) is ^{F -, Cl -, Br -} , -, NO 3 -, N (CN) 2 -, BF 4 -, ClO 4 -, RSO 3 -, RCOO - ( where R is a C1-C9 alkyl group or a phenyl group); _{^{PF 6 -, (CF 3)}} 2 PF 4 -, (CF 3) 3 PF 3 -, (CF 3) 4 PF 2 -, (CF 3) 5 PF -, (CF 3) 6 P -, (CF 3 _{^{SO 3 -) 2, (CF}} 2 CF 2 SO 3 -) 2, (CF 3 SO 3) 2 N -, CF 3 CF 2 (CF 3) 2 CO -, (CF 3 SO 2) 2 CH -, ( ^{_{SF 5) 3 C -, (}} CF 3 SO 2) 3 C -, CF 3 (CF 2) 7 SO 3 -, CF 3 CO 2 -, CH 3 CO 2 - may be selected from the group consisting of. Preferably, the ionic liquid is at least one of EMI-TFSA, BMIM TFSI, OMIM TFSI, EMIM TFSI, EMIM-BF4, EMIM-TCB, BMIM-TFSI, EMIM-SO4, BMIM-BF4, DMIM-BF4, and DMIM-TFSI. It may include one, but is not limited thereto.

Since the ionic liquid is nonvolatile, it has no vapor pressure and has high ionic conductivity. In particular, because of its high polarity, it dissolves inorganic and organometallic compounds well and exists as a liquid in a wide temperature range, so it can be applied to a wide range of chemical fields such as catalyst, separation, and electrochemistry. And low symmetry, weak intermolecular attraction, and charge distribution in cations reduce the melting point. In addition, the ionic liquid not only has non-toxicity, non-flammability, and excellent thermal stability, but also has a wide temperature range as a liquid, high solvation ability, and non-coordinating binding properties. It has physicochemical properties as a solvent. The unique physical and chemical properties of these ionic liquids are greatly influenced by the structure of the cations and anions of the ionic liquid, and can be optimized according to the purpose of use of the user.

For example, the ionic liquid without volatile components does not deform the shape of the dielectric layer DL from various deformations such as bending and external forces, preserves elasticity for a long time, and stably maintains an ionic mixed solution in the dielectric layer DL. By doing so, the life of the capacitive pressure sensor 10 can be extended, and sensing in a high pressure range can be performed. The exemplified EMI:TFSA is an ionic liquid that does not have a typical volatile component, and according to an embodiment of the present invention, a capacitive pressure sensor 10 capable of sensing high pressure while securing a long life may be provided. .

In addition, in order to effectively detect the pressure, a fast response speed of the sensor according to the pressure and a short ion relaxation time may be required. As a crystal polymer of the dielectric layer (DL) according to an exemplary embodiment of the present invention, by dispersing EMI:TFSA in P (VDF-TrFE-CFE), high elasticity is secured even when applied at low pressure, and high sensitivity capacitance capable of measuring pressure even at low pressure application Type pressure sensor 10 can be provided.

In addition, since the ionic liquid contains an ion pair and forms an ionic gel, which is a polymer composite polymer in which the ion pair is dispersed in the dielectric layer DL, the interface with the first electrodes E1 and E2 has a nanometer scale. By forming an electrical double layer (EDL) having a thickness, as will be described later, the capacitive pressure sensor 10 has a high sensitivity of 10.14 kPa-1 at 20 kPa, a fast response time of less than 30 ms, and repetition. It can have a durability of 4,000 cycles with the ON/OFF sequence.

Referring to FIG. 1B, voltages V1 and V2 of constant and different levels are applied to the first and second electrodes E1 and E2, respectively, and the dielectric constant of the dielectric layer DL and the distance between the electrodes E1 and E2 The capacitance C determined by Equation 1 by (d) is determined between the first and second electrodes E1 and E2.

[Equation 1] C=ε*A*d ^-1

C: capacitance between the first and second electrodes E1 and E2

A: opposing areas of the first and second electrodes E1 and E2

d: distance between the first and second poles (E1, E2)

ε: dielectric constant of the dielectric layer (DL)

As shown in Equation 1, the capacitance (C) of the dielectric layer (DL) is the opposite area (A) and distance (d) between the first and second electrodes (E1, E2), and the dielectric constant of the dielectric layer (DL). It can be determined by (ε).

Here, since the dielectric constant (ε) of the dielectric layer (DL) and the opposing area (A) between the first and second electrodes (E1, E2) do not change after the pressure sensor is manufactured, the change in capacitance (C) according to pressure May be determined by the distance d between the first and second electrodes E1 and E2. In an embodiment, the thickness d of the dielectric layer DL for having high sensitivity in the low voltage and high voltage regions may be 300 nm to 200 μm. When the thickness of the dielectric layer DL is less than 300 nm, it is difficult to form a dielectric layer suitable for the sensor because sufficient surface roughness is not formed. When the thickness of the dielectric layer DL exceeds 200 μm, the voltage for reading the capacitance value is It becomes larger than 1V, so the driving voltage can increase.

In addition, the surface roughness including the topology of the micro-fibril may have elasticity so as to be displaced and deformed against external pressure. The surface roughness formed on the surface of the dielectric layer DL may have a square average of several tens of nm. Unlike the flat dielectric layer, due to the surface roughness of the dielectric layer DL according to the present embodiment, the distance between the first and second electrodes E1 and E2 can be greatly changed even at a small pressure. In particular, as the part displaced and the part where deformation occurs simultaneously on the surface roughness of the dielectric layer DL to which pressure is directly applied, the part that is deformed compared to the flat dielectric layer in which only deformation without displacement occurs. Since it is remarkably reduced, a large change occurs in the distance between the first and second electrodes E1 and E2 even with a fine pressure. Accordingly, in the dielectric layer DL having a topology in the form of micro-fibrils in the present embodiment, sensitivity to low pressure may be remarkably improved.

In one embodiment, optionally, at least one of the first electrode layer E1 and the second electrode layer E2 is formed on the flexible and transparent polymer substrate SE, and the first electrode layer E1 and the second electrode layer E2 ) At least one may include first and second graphene layers line-patterned on the polymer substrate. In addition, the capacitive pressure sensor 10 may include an array of capacitor cells each defined at a plurality of intersections between the line patterned first graphene layer and the line patterned second graphene layer. have. The substrate may be a base film such as polyethylene terephthalate (PET), polyimide PI, or polymethyl methacrylate (PMMA), but is not limited thereto.

As described above, by forming a surface roughness including a micro-fibril type topology on the surface of the elastomer, it is possible to improve sensor performance, response speed, recovery speed, and stability. In addition, by introducing a surface roughness including a micro-fibril type topology to the surface of the elastomer, the performance of the capacitive pressure sensor 10 can be remarkably improved by improving the viscoelastic properties. Due to the characteristics of the micro-fibril structure, the distance between electrodes (d) and the relative dielectric constant (ε) can be adjusted at the same time, providing excellent transparency and flexibility, as well as a wide range of external pressures from several Pa to tens of kPa. It is possible to provide a capacitive pressure sensor having excellent sensitivity and a low driving voltage.

2A is a view for explaining a method of manufacturing a capacitive pressure sensor according to an embodiment of the present invention, and FIG. 2B is an image showing the transparency and flexibility of the capacitive pressure sensor according to an embodiment of the present invention. , Figure 2c is a graph showing the transparency of the capacitive pressure sensor according to an embodiment of the present invention.

Referring to FIG. 2A, forming a first electrode layer E1 (S10); On the first electrode layer (E1), disposed on the first electrode layer, including a crystalline polymer and an ionic gel layer containing an ionic liquid (NI, PI) impregnated in the crystalline polymer, the ions Forming a dielectric layer (DL) having a surface roughness controlled by recrystallization of the crystalline polymer chain (PC) of the gel layer (S20); And forming a second electrode layer E2 on the dielectric layer DL (S30). A method of manufacturing a capacitive pressure sensor may be provided.

In one embodiment, the step (S10) of forming the first electrode layer (E1) may include preparing the crystalline polymer and the ionic liquid; Mixing the crystalline polymer and the ionic liquid to form an ionic mixed solution; Coating the ionic mixed solution on the first electrode layer to form an ionic gel layer; And heat-treating the ionic gel layer to recrystallize the chain of the crystalline polymer. The temperature of the heat treatment may be higher than the melting temperature of the crystalline polymer. By heat treatment at a temperature higher than the melting temperature of the crystalline polymer, the dielectric layer DL has a platelet crystalline form due to the folded shape of the crystalline polymer chain PC, and the surface normal of the dielectric layer DL A lamellar structure can be formed based on (N). Here, the folded polymer chains PC may be aligned parallel to the surface normal N of the dielectric layer DL. The coating method may include paint brushing, spray coating, doctor blade, dip-drawing, spin coating, or a combination thereof. , Not limited to these.

In one embodiment, the step of adjusting the cooling rate of the ionic gel layer after the heat treatment step may be further included. Specifically, as the cooling rate of the ionic gel layer is faster, the average square value of the surface roughness decreases, and as the cooling rate of the ionic gel layer is slow, the average square value of the surface roughness may increase. The cooling rate ranges from 5.0° C./min to 0.1° C./min, and when the cooling rate exceeds 5.0° C./min, there is a problem that the surface roughness for high sensitivity performance of the capacitive pressure sensor is lowered, and the cooling If the speed is less than 0.1°C/min, it takes a lot of time to fabricate the thin film, and the roughness becomes too large to cause diffraction with respect to light having a visible wavelength, resulting in a decrease in transparency.

In one embodiment of the present invention, [EMI][TFSA](1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl)amide) and mixed P(VDF-TrFE-CFE) (poly(vinylidene fluoride-co-trifluoroethylene-co -Chlorofluoroethylene)) by controlling the heat treatment temperature of the ionic gel layer to perform melt-recrystallization of the crystalline polymer, so that the surface roughness includes a micro-fibril topology on the surface of the crystalline polymer. Can be formed.

The weight concentration of the ionic liquid may be adjusted to 0 to 60% by weight with respect to the matrix polymer in order to optimize the dielectric behavior of the highly sensitive pressure sensor film. Preferably, the content of the ionic liquid may have a range of more than 0% by weight and less than 45% by weight. In addition, the ionic gel layer may be heat-treated at about 185° C. higher than the melting temperature of the crystalline polymer for 12 hours to promote the growth of a huge lamella on the surface, thereby inducing a rough surface.

In an embodiment, at least one of the first electrode layer and the second electrode layer is formed on a flexible polymer substrate, and at least one of the first electrode layer and the second electrode layer is line-patterned on the polymer substrate. And a second graphene layer. In order to form the line pattern of the electrode, graphene of a large area as a transparent conductive electrode can be grown by chemical vapor deposition (CVD) and transferred onto a PET substrate by performing patterning by dry etching using a sub mask. have. In another embodiment, single-layer graphene may be synthesized on a metal foil (eg, copper foil) by a chemical vapor deposition (CVD) method. The graphene layer can be transferred onto the target PET substrate after deposition of the PMMA sacrificial layer and wet etching of the metal foil with ammonium sulfate solution, and the PMMA layer is removed by immersing the PET/Graphene/PMMA structure in acetone for about tens of minutes. And, the line patterning of the graphene layer may be formed through an oxygen plasma etching process through a metal mask, but the method is not limited thereto. In addition, the capacitive pressure sensor may include an arrangement of capacitor cells each defined at a plurality of intersections between the line patterned first graphene layer and the line patterned second graphene layer.

As described above, a surface roughness including a micro-fibril-type topology is formed on the surface of the crystalline polymer through heat treatment, and between the first graphene layer and the line patterned second graphene layer Since an array of capacitor cells, each defined at a plurality of intersections, can be formed, the N x N array of pixelated, lightweight objects suitable for a transparent and flexible real-time mapping touch panel, and a wide range of pressure from human movements A pressure sensor capable of sensing may be provided. Here, N is a natural number.

2B and 2C, it can be seen that the large-area ionic gel layer on the graphene/PET substrate is mechanically flexible and transparent in the visible range, and the transmittance of the substrate is about PET and graphene/PET, respectively. It was 90.8% and about 87.9%, and it can be seen that the transmittance of the device is still more than 80% at a wavelength of about 550nm.

Experimental example

Material: Terpolymer P (VDF-TrFE-CFE) was purchased from Piezotech company in France. [EMI] [TFSA] was purchased from Sigma-Aldrich.

Graphene Synthesis, Transferring and Patterning: Monolayer Graphene was synthesized by chemical vapor deposition (CVD) on copper foil (Alpha Aesar). The graphene layer was transferred onto the target PET substrate after deposition of the PMMA sacrificial layer and wet etching of the copper foil with an ammonium sulfate solution. The PMMA layer was removed by immersing the PET/Graphene/PMMA structure in acetone for 30 minutes. The graphene electrode array is manufactured by an oxygen plasma etching process through a metal mask.

Pressure sensor device preparation: 15% by weight of P(VDF-TrFE-CFE) solutions with various amounts of [EMI][TFSA] (0, 15, 30, 45 and 60% by weight relative to the polymer) were prepared in acetone . The ionic liquid/polymer solution was stirred at 75° C. for 1 hour, spin-coated on a graphene/PET substrate at 1,000 rpm, and then thermally annealed in a glove box filled with nitrogen. Finally, the upper graphene/PET substrate was placed on the lower PET/graphene/STCIG.

Microstructure and Device Characteristics: The microstructure of the ionic gel was obtained using a scanning electron microscope (FE-SEM, JEOL-7001F) and an atomic force microscope (Nanoscope Iva Digital Instruments). Transmittance was obtained by means of a UV-Vis spectroscopy (Lambda 750, PerkinElmer). The change in capacitance due to pressure was measured using an LCR (inductance, capacitance, resistance) meter (Agilent E4980A) with a computer-controlled universal remote control (Teraleader). The 2D-GIXD pattern was acquired at the Pohang Accelerator Laboratory in Korea. The film was irradiated with a monochromatic X-ray (λ = 0.10608 nm) with a radiation incident angle of 0.12 ° to 0.15 °.

3A to 3C are views for explaining a polymer crystal of a dielectric layer of a capacitive pressure sensor according to a heat treatment temperature according to an embodiment of the present invention, and FIGS. 3D to 3F are 2 of the dielectric layers of FIGS. 3A to 3C. A diagram showing a dimensional grazing incident X-ray diffraction (GIXD) pattern.

3A and 3D, the non-heat-treated ionic gel layer (ascast) prefers a direction in which the polymer chain axis is perpendicular to the surface normal in the needle-shaped P (VDF-TrFE-CFE) crystals, and the meridian region ( meridian regions) in the (110) or (200) plane.

3B and 3E, the ionic gel layer heat-treated at 115° C. lower than the melting temperature of the polymer increases the crystallinity of the ionic gel, but the polymer chain shape and orientation of the non-heat-treated ionic gel layer of FIG. 3A You can see that the state is maintained.

3C and 3F, the chain axis of the polymer in the ionic gel layer melted and recrystallized at 185 °C may be oriented in a direction perpendicular to the substrate (a direction parallel to the surface normal), and the meridian in the 2D GIXD graph A peak may appear at a position rotated approximately 60° from the meridian, not in the area (the lower right part in the graph).

In another embodiment, when the thickness of the dielectric layer is 10 um or more, the 2D GIXD pattern may be observed as a wide ring pattern. This is because the chain axis of the polymer may be placed perpendicular to the substrate surface normal due to a reaction such as epitaxy of the polymer on the graphene surface, but the epitaxy effect with the substrate toward the top of the dielectric layer is insignificant, and the chain axis of the polymer is the substrate surface normal. Can be aligned parallel to. Therefore, the 2D GIXD pattern looks like a ring pattern, but as a result of analysis of the substrate surface, a characteristic of recrystallization after a typical melt may appear.

4A to 4G are atomic force microscopy (AFM) and SEM images of a dielectric layer of a capacitive pressure sensor according to a heat treatment temperature according to an embodiment of the present invention, and FIG. 5 is a heat treatment temperature according to an embodiment of the present invention. And a graph showing the root mean square (RMS) roughness of the capacitive pressure sensor according to the cooling rate.

4A is an AFM image of an unheated ionic gel layer (ascast) containing 30 wt% ionic liquid, and FIG. 4B is an ionic gel layer heat-treated at 115°C containing 30 wt% ionic liquid 4C is an AFM image of an ionic gel layer recrystallized at a cooling rate of 5.0°C/min by heat treatment at 115°C containing 30% by weight of ionic liquid, and FIG. It is an SEM image of an ionic gel layer heat-treated at 185° C. containing an ionic liquid and recrystallized at a cooling rate of 5.0° C./min. It is an AFM image of an ionic gel layer recrystallized at a cooling rate of °C/min, and FIG. 4F is an ionic recrystallized recrystallized at a cooling rate of 0.4 °C/min by heat treatment at 185 °C containing 30% by weight of an ionic liquid. It is an AFM image of the gel layer, and FIG. 4G is an AFM image of an ionic gel layer recrystallized at a cooling rate of 0.1°C/min by heat treatment at 185°C containing 30% by weight of ionic liquid.

Referring to FIGS. 4A to 4G and 5, it can be seen that the ionic gel layer can be controlled by promoting a crystal phase through heat treatment. The surface of the unheated ionic gel layer of FIG. 4A has a root mean square (RMS) roughness (Rq) of about 4.15 nm, and the ionic gel layer of FIG. 4B has a melting temperature (Tm, 140° C.) The surface of the ionic gel layer recrystallized at a cooling rate of 5.0° C./min by heat treatment at 185° C. in FIG. 4C and a square average roughness (Rq) of about 4.0 nm as a heat treatment at 115° C. The roughness (Rq) is about 23.5 nm, the surface of the ionic gel layer heat-treated at 185° C. in FIG. 4E and recrystallized at a cooling rate of 1.6° C./min has a square mean roughness (Rq) of about 40.1 nm, and FIG. The surface of the ionic gel layer heat-treated at 185°C in 4f and recrystallized at a cooling rate of 0.4°C/min has a square mean roughness (Rq) of about 45.2 nm, and heat-treated at 185°C in FIG. 4G to 0.1°C/min. It can be seen that the surface of the ionic gel layer recrystallized at a cooling rate of is approximately 79 nm in square mean roughness (Rq).

Referring to Figure 4d, in contrast, it can be seen that the heat-treated ionic gel layer at 185 °C higher than Tm exhibits a unique shape including a microfibrillar structure having a thickness of 15 nm to 90 nm on the surface. have. In particular, the microstructure of the ionic gel layer depends on the behavior of the semi-crystalline matrix polymer, and the unique microfibrous morphology with large roughness after melt-recrystallization in P(VDF-TrFE) and P(VDF-TrFE-CFE) is observed as a whole. You can see that it is.

As described above, it can be seen that the roughness of the ionic gel can be controlled by optimizing the crystallization rate with a controlled cooling time after thermal annealing above Tm. Specifically, with a slow cooling rate, the number of nuclei decreases and crystallites are inferred from having enough time to grow large area polymer crystals. As a result, very rough surfaces can be formed through largely grown polymer crystals with a controlled crystallization rate. It can be seen that when the cooling rate is adjusted from 5.0 to 0.1 °C/min, the surface roughness of the molten recrystallized ionic gel increases from 23.5 nm to 79 nm, respectively.

6A is a schematic diagram of a pressure sensing system according to an embodiment of the present invention, FIG. 6B is a graph showing a change in capacitance according to a content of an ionic liquid, and FIG. 6C is a graph showing a change in capacitance according to a cooling rate. , FIG. 6D is a graph showing the sensitivity of the capacitive pressure sensor according to the cooling rate, FIG. 6E is a graph showing the change in capacitance according to the change in the pressure load at 500 Hz, and FIG. 6F is a specific pressure measured at 100 kHz. It is a graph showing the change rate according to the time change of the capacitance value, and FIG. 6G is a graph showing the change in capacitance of the capacitive pressure sensor according to the number of repetitions of pressure loading and unloading.

6A, in order to investigate the pressure sensing function of the transparent capacitive pressure sensor by measuring the capacitance value, a pressure range of 0 to 20 kPa was set using a stepping motor as PET/top graphene/ionic gel. It was applied to a capacitor pressure sensor having a layer (STCIG)/lower graphene/glass structure. All of the flexible PET substrates were firmly placed on a rigid glass substrate to realize uniform pressure on the capacitor device. First, after heat treatment under various conditions, the response of the capacitance change after loading and unloading pressure with STCIG containing 30% by weight of ionic gel was investigated as a function of time. When pressure is applied, pressure sensors, including STCIG, reduce the air gap between STCIG and the upper graphene/PET, and nanometer-thick electrical double layers of negative/electrode and positive/electrode in both ionic liquid and upper/lower electrode interfaces ( Electric Double Layer (EDL) can quickly increase the capacitance response. In the absence of the characteristic form of melt-recrystallization of STCIG, the surface of STCIG, as-cast and thermally annealed below Tm, has viscoelastic and sticky characteristics, and can be attached to the upper electrode, and thus, the capacitance value Did not decrease after removing the pressure, so slow pressure sensing may occur as a result. In contrast, the melt-recrystallized STCIG sensor exhibits fast and reproducible sensing behavior, and the microfibre-like shape on the STCIG surface is a highly sensitive sensor that provides elastic behavior of the polymer layer and sufficient air gap volume with a reliable capacitor structure. Means to allow.

Referring to FIG. 6B, the capacitance values when 0% by weight, 15% by weight, 30% by weight and 45% by weight of ionic liquid are contained in an ionic gel layer having a shape like a microfiber by melt-recrystallization. Looking at the change, it can be seen that it increases to 5.12 kPa-1 at a 30% by weight ionic liquid loading, but decreases when the ionic liquid is loaded at 45% by weight. It is judged that STCIG, which has a high ionic liquid fraction of 60% or more, is inferior due to slow separation of the upper electrode from the ionic gel layer due to the viscous and viscoelastic surface having an uneven form of agglomerated ionic liquid. In particular, the microfiber-like shape of the melt-recrystallized STCIG surface with 30% by weight of ionic liquid allows a high air gap volume within the interface between the STCIG and the graphene electrode, resulting in high sensitivity as well as reliable device reliability. It may be possible to detect.

Referring to FIG. 6C, it can be seen that the slower the cooling rate, the greater the change in the capacitance value. Referring to FIG. 6D, it can be seen that the slower the cooling rate, the greater the sensitivity of the sensor. When the ionic gel layer is melted and recrystallized at a cooling rate of 0.1 °C/min, it can be seen that the rough surface of the ionic gel layer exhibits the highest sensitivity of 10.14 kPa-1 in a wide pressure sensing range up to 20 kPa. . This appears to be due to the surface of the ionic gel layer having an air gap at the interface between the ionic gel and the electrode. And, the sensor manufactured with a fast cooling rate showed low sensitivity of 6.52 kPa-1 and 5.13 kPa-1 for 0.4° C./min and 1.6° C./min, respectively.

6E, it was found that the ionic gel layer has a high sensitivity as well as a topology characteristic of a microfiber, which allows a fast response time of capacitance change by loading/unloading pressure for a wide range of application pressures from 1 to 20 kPa. I can.

Referring to FIG. 6F, the capacitance value rapidly rises and falls within 30 ms with a pressure of 2.5 kPa at 100 kHz, indicating elastic deformation and recovery of the sensor. The fast response time of the sensor due to the topological shape of the surface of the ionic gel layer is based on the elastomer and artificially microstructured ionic gel, which appears to indicate that the ionic gel layer exhibits weak viscoelastic behavior.

Referring to FIG. 6G, it shows excellent cyclic stability without deterioration of capacitance change in more than 4,000 durable compression/release cycles (5 seconds for each loading and unloading interval) at 5 kPa pressure, which is a high mechanical durability of the sensor and The robustness can be confirmed.

In order to commercialize the application product of the pressure sensor, the highly sensitive pressure sensor can operate at a wide range of pressures from light weight objects to human movements by using the ionic gel layer of the present invention. In particular, the pressure sensor of the present invention requires high sensitivity in a wide pressure range, and can have flexibility and transparency.

7A is a graph showing the change in capacitance of the capacitive pressure sensor by aluminum pellets, FIG. 7B is a graph showing the change in capacitance of the capacitive pressure sensor by soft finger touch, and FIG. 7C is It is a graph showing the change in capacitance of the capacitive pressure sensor, and FIG. 7C is a graph showing the change in the capacitance of the capacitive pressure sensor according to bending repetition.

Referring to Figure 7a, it can be seen that the capacitance of the pressure sensor of the present invention is changed by the weight of 80 mg Al pellets at a pressure of 100 Pa.

7B and 7C, the pressure sensor successfully detects human motions such as fine finger touch (Fig. 7b) and bending motion (Fig. 7c) applied at 5 kPa to 10 kPa and 10 kPa to 15 kPa, respectively. can do. In order to further verify the reliable mechanical flexibility of the sensor, the lower PET/graphene/STCIG and upper graphene/PET were encapsulated together with an external flexible substrate to prevent peeling of the disposed upper graphene/PET substrate.

Referring to FIG. 7D, durability is a result obtained by manually repeating the bending/releasing cycle test over 150 cycles with a bending radius of 5 mm, and shows excellent cyclic stability without deterioration of the capacitance change.

FIG. 8A is a schematic diagram of a 12×12 pressure sensor matrix, FIG. 8B is an image photograph of a pressure sensor array made of patterned graphene and a dielectric layer, and FIG. 8C is a diagram showing an equivalent circuit of a 12×12 pressure sensor matrix. , FIG. 8D is a graph showing the magnitude of capacitance change by multi-touch. As described above, the graphene array having a line pattern on each of the upper and lower electrodes can pixelize a large-area ionic gel layer into an nxn (e.g., 12x12) capacitor array without a pixelation process. A tactile sense touch panel can be implemented.

Referring to FIGS. 8A and 8C, an array of pressure sensors including an ionic gel layer may be intersected with the graphene patterned at the bottom line and the graphene array at the top to implement a matrix array. The images in Figures 8A and 8C show a 12x12 pressure sensor array.

Referring to FIG. 8B, a single and multi-touch 12×12 pressure sensor array is shown, and referring to FIG. 8D, a sensed position and size of tactile pressure of single and multi-touch of FIG. 8B are visually shown.

9A is an AFM (atomic force microscopy) height profile of the dielectric layer of the capacitive pressure sensor according to the heat treatment temperature according to an embodiment of the present invention, and FIG. 9B is an AFM of the dielectric layer of the capacitive pressure sensor according to the heat treatment temperature. atomic force microscopy) 3D height image, and FIG. 9C is a graph showing the difference in height of the surface roughness of the dielectric layer of the capacitive pressure sensor according to the heat treatment temperature. 9A to 9C, the height profile and 3D AFM image of the surface roughness of the molten recrystallized ionic gel by adjusting the cooling rate from 5.0 to 0.1 °C/min show that the slower the cooling rate, the slower the crystallization occurs. It can be seen that the phase difference increases.

10A to 10C are graphs showing changes in capacitance of a capacitive pressure sensor according to pressure loading and pressure unloading. Referring to FIGS. 10A to 10C, the response of the capacitance change after loading and unloading a pressure of 20 kPa is shown as a function of time, and it can be seen that the response speed of the sensor increases as the surface roughness becomes rough.

11A and 11B are graphs showing changes in capacitance of a capacitive pressure sensor according to different frequency changes at no-load pressure. EDL is induced in both the aforementioned ionic gel and the electrode interface, so the sensor can have a higher capacitance value. In order to realize the effective formation of this EDL, the capacity change according to the frequency change was measured.

Referring to FIGS. 11A and 11B, it can be seen that the capacity change decreases as the frequency increases in the frequency range of 0.02 to 10 kHz. It is judged that EDL was not effectively formed at a frequency of about 1 kHz or more, and as a result, the capacitance value decreased. Also, when the air gap of the dielectric layer DL is large, the capacitance affected by the weak frequency may be reduced. In contrast, an air gapless dielectric layer with a thermally deposited top metal electrode showed a decrease in capacitance at frequencies higher than 1 kHz. It seems that the EDL is effectively formed at approximately 500 Hz to obtain the maximum sensitivity of the pressure sensor.

From the above experimental results, a highly sensitive, transparent and flexible pressure sensor array can be implemented with an ionic gel layer composed of P(VDF-TrFE-CFE) polymer and [EMIM][TFSI] ionic liquid. The ionic gel layer exhibits high sensitivity in the form of a rough surface obtained from the molecular structure during melt-crystallization of the polymer. The topological properties of the surface of the melt-recrystallized ionic gel layer can be measured with a high sensitivity of approximately 11.2 kPa-1 in the range of 20 kPa. In addition, the capacitive pressure sensor of the present invention has a detection rate of less than 50 ms and exhibits reliable cycles during 4,000 loading/unloading cycles. Reliable sensors may be suitable for detecting light weight objects, human contact and movement. In addition, the n×n touch panel may be implemented with a dielectric layer including an ionic gel and a graphene arrangement. The transparent and flexible pressure sensor including the ionic gel layer having the surface roughness of the present invention may be suitable for wearable electronic devices including soft robots, electronic skin, health monitoring and mobile displays.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and that various substitutions, modifications, and changes are possible within the scope of the technical spirit of the present invention. It will be obvious to those who have knowledge.

10: capacitive pressure sensor
E1: first electrode layer
DL: dielectric layer
E2: second electrode layer
PC: crystalline polymer
PI, NI: ionic liquid
PC: polymer chain
AG: Air gap
EDL: electric double layer

Claims (16)

A first electrode layer;
An ionic gel layer disposed on the first electrode layer and comprising a crystalline polymer and an ionic liquid impregnated in the crystalline polymer, and the chain of the crystalline polymer of the ionic gel layer A dielectric layer having a surface roughness controlled by recrystallization; And
Capacitive pressure sensor comprising a second electrode layer disposed on the dielectric layer. The method of claim 1
The capacitive pressure sensor,
The capacitive pressure sensor further comprising an air gap formed through the surface roughness between the dielectric layer and any one of the first electrode layer and the second electrode layer. The method of claim 1
The capacitive pressure sensor,
A capacitive pressure sensor further comprising an electric double layer (EDL) formed between an interface of the dielectric layer and any one of the first electrode layer and the second electrode layer. The method of claim 1
The surface roughness is a capacitive pressure sensor including a topology in the form of micro-fibril. The method of claim 1
The recrystallization of the chain of the crystalline polymer includes the chain of the crystalline polymer being aligned parallel to the surface normal of the dielectric layer,
The crystalline polymer is a capacitive pressure sensor having a lamella structure based on a surface normal of the dielectric layer and having a platelet crystalline form due to the chain bending. The method of claim 1
The root mean square (RMS) of the surface roughness is a capacitive pressure sensor having a range of 0.5 nm to 500 nm. The method of claim 1
The content of the ionic liquid impregnated in the crystalline polymer is a capacitive pressure sensor having a range of more than 0% by weight and less than 60% by weight. The method of claim 1
The crystalline polymers are PVDF, P(VDF-TrFE), P(VDF-CTFE), P(VDF-CFE), P(VDF-HFP), P(VDF-TrFE-CTFE), P(VDF-TrFE- CFE) and a PVDF based copolymer comprising P(VDF-TrFE-HFP), a capacitive pressure sensor. The method of claim 1
The ionic liquid contains at least one of EMI-TFSA, BMIM TFSI, OMIM TFSI, EMIM TFSI, EMIM-BF4, EMIM-TCB, BMIM-TFSI, EMIM-SO4, BMIM-BF4, DMIM-BF4, and DMIM-TFSI. Capacitive pressure sensor. The method of claim 1
At least one of the first electrode layer and the second electrode layer is formed on a polymer substrate,
At least one of the first electrode layer and the second electrode layer includes first and second graphene layers line-patterned on the polymer substrate,
The capacitive pressure sensor has an arrangement of capacitor cells each defined at a plurality of intersections between the line patterned first graphene layer and the line patterned second graphene layer. Forming a first electrode layer;
On the first electrode layer, disposed on the first electrode layer, comprising an ionic gel layer comprising a crystalline polymer and an ionic liquid impregnated in the crystalline polymer, the crystallinity of the ionic gel layer Forming a dielectric layer having a surface roughness controlled by recrystallization of a polymer chain; And
A method of manufacturing a capacitive pressure sensor comprising forming a second electrode layer on the dielectric layer. The method of claim 11,
The step of forming the dielectric layer,
Preparing the crystalline polymer and the ionic liquid;
Mixing the crystalline polymer and the ionic liquid to form an ionic mixed solution;
Coating the ionic mixed solution on the first electrode layer to form an ionic gel layer; And
Heat treatment of the ionic gel layer to recrystallize the chains of the crystalline polymer. The method of claim 12,
The temperature of the heat treatment is higher than the melting temperature of the crystalline polymer. The method of claim 12,
The method of manufacturing a capacitive pressure sensor further comprising the step of controlling the cooling rate of the ionic gel layer. The method of claim 14,
The cooling rate is a method of manufacturing a capacitive pressure sensor having a range of 5.0 ℃ / min to 0.1 ℃ / min. The method of claim 11,
At least one of the first electrode layer and the second electrode layer is formed on a polymer substrate,
At least one of the first electrode layer and the second electrode layer includes first and second graphene layers line-patterned on the polymer substrate,
The capacitive pressure sensor is a capacitive pressure sensor having an array of capacitor cells each defined at a plurality of intersections between the line patterned first graphene layer and the line patterned second graphene layer. Manufacturing method.

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