KR102141666B1 - Dielectric for pressure sensor, method of manufacturing the same and capacitive type pressure sensor - Google Patents

Abstract

The present invention relates to a method for manufacturing a dielectric for a pressure sensor, the method for manufacturing a dielectric for a pressure sensor according to an embodiment of the present invention (a) a mixture of two different first polymer and second polymer mixture The step of preparing, (b) mixing a foaming agent and a solution of a blowing agent in which the surfactant is dissolved in the polymer mixture to prepare a second mixture, (c) the acid in which the acidic compound and the surfactant are dissolved in the second mixture And mixing the aqueous solution of the compound to prepare a dielectric composition and (d) heating the dielectric composition to cure the first polymer and the second polymer.

Description

Dielectric for pressure sensor and its manufacturing method and capacitive pressure sensor{DIELECTRIC FOR PRESSURE SENSOR, METHOD OF MANUFACTURING THE SAME AND CAPACITIVE TYPE PRESSURE SENSOR}

The present invention relates to a dielectric for a pressure sensor, a method for manufacturing the same, and a capacitive pressure sensor, the dielectric for a pressure sensor in which pores are formed using an elastic polymer, and a method for manufacturing the same, and a capacitive pressure sensor having the same will be.

The pressure sensor can be divided into a mechanical method using a mechanical elastic force against an external pressure and an electric method for detecting that an electrical signal changes according to the external pressure.

Among them, there are piezoelectric pressure sensors, piezoresistive pressure sensors, and capacitive pressure sensors as pressure sensors using an electrical method. In particular, the capacitive pressure sensor is a method of forming a dielectric between electrodes of the pressure sensor to sense a change in the capacitance that changes when the dielectric is compressed by external pressure. Sensitivity may vary depending on the type of dielectric, and it has the advantage of being able to measure accurate pressure compared to mechanical pressure sensors and other electrical pressure sensors.

The dielectric used in the capacitive pressure sensor uses an elastomer compressed by external pressure and then recovered. Depending on the properties of the elastomer, the sensitivity and pressure range of the pressure sensor are determined.

The dielectric used in the conventional capacitive pressure sensor was manufactured by forming pores in an elastomer. The elastic force of the dielectric, that is, the sensitivity of the pressure sensor may vary depending on the size and density of the elastomer and the pores formed as the matrix of the dielectric. However, it was not easy to control the properties of the dielectric so as to have the sensitivity required to be used as a specific pressure sensor, and there was a problem in that performance was poor and unnecessary processes were involved in the process.

Therefore, the present invention is to solve a number of problems, including the above problems, the pressure sensor dielectric and the manufacturing method and the capacitive pressure sensor having the same for the pores are formed using two different polymers It is aimed at providing.

In addition, an object of the present invention is to improve the sensitivity of the pressure sensor by adjusting the size and density of pores formed in the dielectric for the pressure sensor.

However, these problems are exemplary, and the scope of the present invention is not limited thereby.

According to one aspect of the present invention for solving the above problems, (a) mixing two different first and second polymers to prepare a polymer mixture, (b) blowing agent and surfactant in the polymer mixture Preparing a second mixture by mixing an aqueous solution of a blowing agent dissolved therein, (c) preparing an dielectric composition by mixing an aqueous solution of an acidic compound in which the acidic compound and the surfactant are dissolved in the second mixture, and (d) A method of manufacturing a dielectric for a pressure sensor is provided, comprising heating the dielectric composition to cure the first polymer and the second polymer.

In the method of manufacturing the dielectric for the pressure sensor, the first polymer and the second polymer are each at least one selected from the group consisting of polybutyrate, polyurethane, and polydimethylsiloxane (PDMS). Can.

In step (b) of the method for manufacturing the dielectric for the pressure sensor, the blowing agent is in the group consisting of H ₂ CO ₃ , LiHCO ₃ , NaHCO ₃ , KHCO ₃ , Mg(HCO ₃ ) ₂ and Ca(HCO ₃ ) ₂ It includes at least one selected, and in step (c), the acidic compound may include citric acid (C ₆ H ₈ O ₇ ) or acetic acid (CH ₃ COOH).

In step (c) of the method for manufacturing the dielectric for the pressure sensor, the weight ratio of the foaming agent and the acidic compound in the dielectric composition is 25 wt% to 40 wt%, and in the step (d), heating is 80° C. to 150° C. It may be characterized by performing at ℃.

In at least one of steps (c) to (d) of the method for producing a dielectric for a pressure sensor, the blowing agent and the acidic compound react to produce a gas and the gas is on the polymer mixture matrix. It may be characterized by forming pores.

In the method for producing the dielectric for the pressure sensor, the higher the content of the polymer having a relatively high viscosity among the first and second polymers, the higher the content of the blowing agent, the higher the content of the acidic compound, and the pores It can be characterized in that the larger the size, the higher the sensitivity to the pressure of the dielectric.

According to another aspect of the present invention for solving the above problems, a polymer mixture in which two different first and second polymers are mixed is used as a matrix, wherein pores are formed in the polymer mixture matrix. , It provides dielectric for pressure sensor.

In the dielectric for the pressure sensor, the first polymer and the second polymer may each be at least one selected from the group consisting of polybutyrate, polyurethane, and polydimethylsiloxane (PDMS).

In the dielectric for the pressure sensor, the pores may be formed in the polymer mixture matrix by a gas generated by reaction of a blowing agent and an acidic compound.

In the dielectric for the pressure sensor, the blowing agent includes at least one selected from the group consisting of H ₂ CO ₃ , LiHCO ₃ , NaHCO ₃ , KHCO ₃ , Mg(HCO ₃ ) ₂ and Ca(HCO ₃ ) ₂ , and The acidic compound may include citric acid (C ₆ H ₈ O ₇ ) or acetic acid (CH ₃ COOH).

According to another aspect of the present invention for solving the above problems, the upper electrode and the lower electrode disposed spaced apart from each other; And a polymer mixture interposed between the upper electrode and the lower electrode, in which two different types of the first polymer and the second polymer are mixed as a matrix, wherein pores are formed in the polymer mixture matrix. It provides a capacitive pressure sensor comprising a; dielectric.

In the capacitive pressure sensor, the first polymer and the second polymer may each be at least one selected from the group consisting of polybutyrate, polyurethane, and polydimethylsiloxane (PDMS). .

In the capacitive pressure sensor, the pores may be characterized by being formed in the polymer mixture matrix by a gas generated by the reaction of a blowing agent and an acidic compound.

In the capacitive pressure sensor, the blowing agent includes at least one selected from the group consisting of H ₂ CO ₃ , LiHCO ₃ , NaHCO ₃ , KHCO ₃ , Mg(HCO ₃ ) ₂ and Ca(HCO ₃ ) ₂ , The acidic compound may include citric acid (C ₆ H ₈ O ₇ ) or acetic acid (CH ₃ COOH).

According to an embodiment of the present invention made as described above, using two different types of polymers and foaming agents and acidic compounds provides a pressure sensor dielectric having pores and a manufacturing method thereof and a capacitive pressure sensor having the same can do.

In addition, according to the present invention, there is an effect of improving the sensitivity of the pressure sensor by controlling the size and density of pores formed in the dielectric for the pressure sensor by adjusting the ratio in the composition of the polymer, blowing agent and acidic compound.

Of course, the scope of the present invention is not limited by these effects.

1 is a flow chart showing a method of manufacturing a dielectric for a pressure sensor according to an embodiment of the present invention.
2 is a schematic diagram showing a method of manufacturing a dielectric for a pressure sensor according to an embodiment of the present invention.
3 is a schematic diagram showing a method of manufacturing a pressure sensor according to an embodiment of the present invention.
4 and 5 are scanning electron microscopy (SEM) photographs showing pores formed on surfaces according to comparative examples of the present invention.
Figure 6 shows the results of the dielectric constant change experiment of the pressure sensor dielectric according to a comparative example of the present invention.
7 is a photograph showing an aqueous sodium hydrogen carbonate and citric acid solution according to an embodiment of the present invention.
Figure 8 shows the experimental results of the capacitance change rate (ΔC/C ₀ ) measurement of the dielectric for a pressure sensor according to an embodiment of the present invention.
9 is a compression stress-compression elongation graph of a dielectric for a pressure sensor according to embodiments of the present invention.
10 is a graph showing a result of measuring a rate of change of capacitance (ΔC/C ₀ ) of a dielectric for a pressure sensor according to embodiments of the present invention.
11 is a scanning electron microscopy (SEM) pictures of a dielectric cross section according to the curing temperature in the third experimental example of the present invention.
12 is a graph showing a relationship between a pressure sensor dielectric and a capacitance change rate (ΔC/C ₀ ) according to a curing temperature in a third experimental example of the present invention.
13 is a graph showing the relationship between the compressive stress and the compressive strain of the pressure sensor dielectric according to the curing temperature in the third experimental example of the present invention.
14 to 16 are graphs obtained by dividing the sensitivity according to the curing temperature of the pressure sensor dielectric according to the curing temperature according to the pressure range in the third experimental example of the present invention.
17 is a view showing the results of micro-CT analysis of the dielectric for pressure sensors according to the ratio of pore-forming precursors in the third experimental example of the present invention.
18 is a graph showing the relationship between the pressure change rate and the capacitance change rate (ΔC/C ₀ ) of the pressure sensor dielectric according to the pore forming precursor ratio in the third experimental example of the present invention.
19 to 21 are graphs obtained by dividing the sensitivity of the dielectric for the pressure sensor according to the ratio of the pore-forming precursor in the third experimental example of the present invention by pressure range.
22 is a diagram illustrating an experimental result of evaluating the lowest pressure measurable with a pressure sensor in the third experimental example of the present invention.
23 is a graph showing the reaction time according to the pressure of the pressure sensor in the third experimental example of the present invention, and FIG. 24 is an enlarged graph of the M1 region of FIG. 23.
25 is a graph showing the reaction time according to the pressure of the pressure sensor in the third experimental example of the present invention, FIG. 26 is an enlarged graph of the M2 region of FIG. 25, and FIG. 27 is an enlarged graph of the M3 region of FIG. 25. to be.
28 and 29 are graphs showing the reliability evaluation results of the pressure sensor in the third experimental example of the present invention.

For a detailed description of the present invention, which will be described later, reference is made to the accompanying drawings that illustrate, by way of example, specific embodiments in which the present invention may be practiced. These examples are described in detail enough to enable those skilled in the art to practice the present invention. It should be understood that the various embodiments of the invention are different, but need not be mutually exclusive. For example, certain shapes, structures, and properties described herein may be implemented in other embodiments without departing from the spirit and scope of the invention in relation to one embodiment. In addition, it should be understood that the location or placement of individual components within each disclosed embodiment can be changed without departing from the spirit and scope of the invention. Therefore, the following detailed description is not intended to be taken in a limiting sense, and the scope of the present invention, if appropriately described, is limited only by the appended claims, along with all ranges equivalent to those claimed. In the drawings, similar reference numerals refer to the same or similar functions across various aspects, and length, area, thickness, and the like may be exaggerated for convenience.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings in order to enable those skilled in the art to easily implement the present invention.

Dielectric manufacturing method for pressure sensor

A method of manufacturing the dielectric 100 for a pressure sensor according to an embodiment of the present invention will be described with reference to FIGS. 1 to 2.

1 is a flow chart showing a method of manufacturing a pressure sensor dielectric 100 according to an embodiment of the present invention, Figure 2 is a schematic diagram showing a method of manufacturing a pressure sensor dielectric 100 according to an embodiment of the present invention to be.

Referring to FIG. 1, a method of manufacturing the dielectric 100 for a pressure sensor, (a) mixing two different first polymers 210 and second polymers 220 to prepare a polymer mixture 200 Step, (b) preparing the second mixture 300 by mixing the foaming agent 310 and the aqueous solution 350 of the surfactant 320 dissolved in the polymer mixture 200, (c) the second mixture ( Preparing the dielectric composition 400 by mixing the acidic compound 410 and the aqueous solution of the acidic compound 450 in which the surfactant 320 is dissolved in 300) and (d) heating the dielectric composition 400 to obtain the first polymer. It may include the step of curing the 210 and the second polymer 220.

First, in step (a), two different types of polymers may be elastomers having elasticity as a polymer. The polymer used for the pressure sensor dielectric 100 may be compressed by external pressure and then restored to its original state. When compressed by external pressure, the dielectric constant of the dielectric changes, acting as a sensor, regaining its initial state, and the polymer may have elasticity to have the same performance even after repeated use. Accordingly, two different types of polymers according to an embodiment of the present invention may be elastic elastomers. According to an embodiment of the present invention, in step (a), the first polymer 210 and the second polymer 220 are polybutyrate, polyurethane, and polydimethylsiloxane (PDMS). It may be at least one selected from the group consisting of. The first polymer 210 and the second polymer 220 may preferably include polydimethylsiloxane (PDMS) or polybutyrate including siloxane groups (Siloxane, -Si-O-). have.

A polymer mixture 200 in which two different types of the first polymer 210 and the second polymer 220 are mixed may be formed. In the case of a dielectric produced using only one polymer, the durability and the dielectric constant change due to elasticity are weak, but when two different types of polymer are used, the durability is improved, and in particular, the rate of change in capacitance can be adjusted by adjusting the mixing ratio. have. This has the effect of adjusting the sensitivity, which is one of the factors measuring the performance of the pressure sensor.

On the other hand, according to an embodiment of the present invention, the polymer mixture 200, compared to 100% by weight of the polymer mixture 200, the first polymer 210 is 35% to 55% by weight, the second polymer 220 is 45% to 65% by weight.

Since the first polymer 210 and the second polymer 220 are different types of polymers, physical properties such as molecular weight and viscosity may be different. In particular, when a lot of polymers having a higher viscosity are included, the viscosity of the dielectric 100 for a pressure sensor increases, so that an elastic force can be improved. This has the effect of improving the durability that can show the same level of performance even when the pressure sensor is repeatedly used several times. Accordingly, the polymer mixture 200 may be prepared by adjusting the mixing ratio of the first polymer 210 and the second polymer 220. Preferably, the first polymer 210 having a low viscosity may include 45% by weight, and the second polymer 220 may include 55% by weight.

Next, in step (b), a foaming agent aqueous solution 350 including the foaming agent 310 and the surfactant 320 may be prepared. The blowing agent 310 may be included to generate a gas when the dielectric composition 400 is cured to form the dielectric 100 for a pressure sensor. The blowing agent 310 may generate gas by a temperature change or a chemical reaction. Gas generation by heating is simple, but physical properties may change with temperature, but gas generation by chemical reaction can control the content of additives to form pores by gas generation without changing physical properties.

The surfactant 320 may be included in the blowing agent aqueous solution 350 to disperse the blowing agent 310 in the polymer mixture 200. When the blowing agent 310 is polarized by ionizing in the blowing agent aqueous solution 350, and the polymer has hydrophobicity, the aqueous blowing agent solution 350 may be phase separated from the polymer mixture 200, in this case, step (d). In the gas generated by the blowing agent 310 does not uniformly form pores in all regions of the polymer, and may form pores in only some regions. That is, it means that some regions of the pressure sensor dielectric 100 may have different physical properties. Therefore, the surfactant 320 may be mixed with the aqueous foaming agent solution 350 to disperse the foaming agent 310 in the polymer mixture 200. The surfactant 320 may be preferably sodium dedocylbenzenesulfonate (SDBS).

Meanwhile, according to an embodiment of the present invention, in step (b), the blowing agent 310 is H ₂ CO ₃ , LiHCO ₃ , NaHCO ₃ , KHCO ₃ , Mg(HCO ₃ ) ₂ and Ca(HCO ₃ ) ₂ It includes at least one selected from the group consisting of, the concentration of the foaming agent aqueous solution 350, the surfactant 320 is 0.1% to 0.3% by weight and the concentration of the foaming agent 310 may be 2.7% to 4.9% by weight have.

The blowing agent 310 may be present by being ionized in the blowing agent aqueous solution 350, and may generate hydrogen carbonate ions (HCO 3 ⁻ ) as anions. Hydrogen carbonate ions may generate gas by increasing temperature or reacting with hydrogen ions (H ⁺ ) of acidic compounds. The gas generated by the chemical reaction may vaporize at the curing temperature of the dielectric composition 400 to form the pores of the dielectric 100 for the pressure sensor. Preferably, the blowing agent 310 may be NaHCO ₃ Baked Soda. The surfactant 320 may be added in a small amount in the aqueous blowing agent solution 350 to well disperse the blowing agent 310 in the polymer mixture 200. The second mixture 300 prepared in step (b) may form an emulsion in which a hydrophobic polymer and a polar blowing agent aqueous solution 350 are mixed by the surfactant 320.

On the other hand, the blowing agent 310 may affect the size and density of the pores of the dielectric for the pressure sensor, and the content may be adjusted in the blowing agent aqueous solution 350 to form an emulsion in the second mixture 300. . As the content of the blowing agent 310 increases, the density of pores can be increased because more gas is generated. Therefore, in order to prepare the dielectric 100 for a pressure sensor having a sensitivity sufficient to be used as a pressure sensor, the concentration of the blowing agent 310 in the blowing agent aqueous solution 350 is 2.7% to 4.9% by weight, and the surfactant ( The concentration of 320) may be 0.1% to 0.5% by weight. More preferably, the blowing agent 310 is 5wt%, and the surfactant 320 may be 0.3wt%.

Next, in step (c), an acidic compound aqueous solution 450 including an acidic compound 410 and a surfactant 320 may be prepared. The acidic compound 410 may be included to react with the blowing agent 310 to generate gas. Hydrogen ions contained in the blowing agent 310 react with hydrogen ions of the acidic compound 410 to produce gas. The surfactant 320 may be included in the aqueous solution of the acidic compound 450 and disperse the acidic compound 410 in the polymer mixture 200, similarly to the aqueous solution 350 of the blowing agent.

On the other hand, according to an embodiment of the present invention, in step (c), the acidic compound 410 has a pH of 3 to 5, the acidic compound aqueous solution 450, the concentration of the surfactant 320 is 0.1% by weight to It is 0.5% by weight and the concentration of the acidic compound 410 may be 64.7% by weight to 74.9% by weight.

When the pH of the acidic compound 410 is a low acid, it may need to be adjusted to have a pH sufficient to generate the blowing agent 310 and gas because it may affect the polymer of the dielectric 100 for pressure sensors. have. Preferably, the acidic compound 410 may have a pH of 3.5, and may include citric acid (C ₆ H ₈ O ₇ ). And, the acidic compound 410 can also affect the size and density of the pores of the dielectric 100 for the pressure sensor, and the content in the acidic compound aqueous solution 450 to form an emulsion in the dielectric composition 400. Can be adjusted. As the content of the acidic compound 410 increases, the density of pores can be increased because more gas is generated. Therefore, in order to prepare a dielectric 100 for a pressure sensor having a sensitivity sufficient to be used as a pressure sensor, the acidic compound 410 in the acidic compound aqueous solution 450 has a concentration of 64.7 wt% to 74.9 wt%, and an interface The active agent 320 may have a concentration of 0.1% to 0.5% by weight. More preferably, the acidic compound 410 may have a concentration of 70% by weight, and the surfactant 320 may have a concentration of 0.3% by weight.

In addition, the dielectric composition 400 may be prepared by mixing the acidic compound aqueous solution 450 with the second mixture 300. According to an embodiment of the present invention, the pressure sensor dielectric composition 100 is a mixture of two different polymers, the polymer mixture 200 and the blowing agent 310, the acidic compound 410 and the surfactant 320 It contains a dissolved aqueous solution, the aqueous solution may be dispersed in the polymer mixture (200).

On the other hand, in the step (c), the dielectric composition 400, the dielectric composition 400, 100% by weight of the foaming agent aqueous solution 350 and the acidic compound aqueous solution 450 is a total of 40% to 50% by weight, the polymer mixture ( 200) may include 50% to 60% by weight.

The dielectric 100 for the pressure sensor may be prepared by curing the dielectric composition 400, and physical properties of the dielectric 100 for the pressure sensor may be changed according to the composition ratio of the dielectric composition 400. The composition ratio of each of the polymer composition 200 included in the dielectric composition 400, the foaming agent aqueous solution 350, and the acidic compound aqueous solution 450 may be adjusted to control the composition ratio of 100% by weight of the dielectric composition 400. The lower the content of the polymer having a low viscosity in the polymer mixture 200, the higher the proportion of the blowing agent 310 and the acidic compound 410 in the dielectric composition 400, the larger the size and density of the pores in the dielectric 100 for the pressure sensor. Increases, the sensitivity of the pressure sensor increases. Accordingly, the foaming agent 310 and the acidic compound 410 in the dielectric composition 400 are 40% to 50% by weight, compared to 100% by weight of the dielectric composition 400, and the polymer mixture 200 is 50% to 60% by weight. It may be, preferably, the blowing agent aqueous solution 350 and the acidic compound aqueous solution 450 may include 45% by weight, and the polymer mixture may include 55% by weight.

Next, in step (d), the dielectric composition 400 may be heated to cure the first polymer 210 and the second polymer 220. The dielectric composition 400 in which the polymer mixture 200, the aqueous foaming agent solution 350, and the acidic compound aqueous solution 450 are mixed is a material having a liquid viscosity. The dielectric 100 for a pressure sensor may be manufactured by heating and curing it.

On the other hand, in step (d), heating is performed at 80° C. to 150° C., the blowing agent 310 reacts with the acidic compound 410 to produce gas, and the gas forms pores on the polymer mixture 200 matrix. can do.

When the polymer of the dielectric composition 400 is cured by heating, the blowing agent 310 and the acidic compound 410 can generate gas to form pores on the polymer mixture 200 matrix. When the dielectric composition 400 is heated, the blowing agent 310 and the acidic compound 410 accelerate the reaction to generate gas, and the gas generated while curing the polymer forms pores on the matrix of the polymer mixture 200. The size and distribution of the pores formed may vary depending on the content ratio of the polymer and the blowing agent 310 and the acidic compound 410, and the shape of the pores may also vary depending on the curing temperature of the dielectric composition 400.

When the curing temperature of the dielectric composition 400 is high, gas can be generated at a rapid rate to form large pores on the matrix before the polymer is cured. On the other hand, if the curing temperature is low, since sufficient time is given for the polymer to cure, the pore size is small, and can be formed with a uniform distribution. Therefore, the curing temperature of the dielectric composition can be adjusted to have the sensitivity required for the dielectric 100 for the pressure sensor. The dielectric composition 400 may be heated at 80°C to 150°C, and preferably 110°C.

Pressure sensor manufacturing method

Next, with reference to FIG. 3, a method of manufacturing a pressure sensor 500 including a dielectric 100 for a pressure sensor according to an embodiment of the present invention will be described.

3 is a schematic diagram showing a method of manufacturing a pressure sensor 500 according to an embodiment of the present invention.

First, a fully cured dielectric 100 for a pressure sensor is manufactured in the form of a substrate, and a silver (Ag) nanowire 600 is spray coated on the top, and then partially cured on the top to maintain the viscosity. The dielectric 100 is stacked in the form of a substrate. The dielectric 100 for the pressure sensor-silver nanowire 600-a stacked structure in the form of the dielectric 100 for the pressure sensor may form the dielectric electrode 510 in the pressure sensor 500. A dielectric 100 for a pressure sensor manufactured in the form of a foam is prepared on the dielectric electrode 510. Since the adhesive strength of the pressure sensor dielectric 100 is maintained, it is possible to bond with the dielectric 100 for pressure sensor in the form of a foam. After bonding the dielectric 100 for the pressure sensor in the form of a foam, the dielectric 100 for the pressure sensor in the form of a partially cured substrate is heated until completely cured.

When the dielectric electrode 510 is completely cured by laminating the dielectric electrode 510 on which the foam manufactured by the above process is stacked, a unit cell of the pressure sensor 500 is formed. When the unit cells are patterned in an array form, the pressure sensor 500 can be manufactured.

Example 1

Hereinafter, a dielectric for a pressure sensor using polydimethylsiloxane (PDMS) and Ecoflex according to an embodiment of the present invention will be described with reference to FIGS. 4 to 10.

Analysis of pore shape according to curing temperature

4 to 6, the form of pores formed in the dielectric for the pressure sensor according to the curing temperature of the dielectric composition will be described.

First, a sample used for morphological analysis of pores will be described. In this experiment, the polymer uses PDMS polymer, the blowing agent uses 7% by weight of NaHCO ₃ , and the acidic compound uses 16% by weight of citric acid.

The mixture was prepared by mixing the PDMS polymer and the curing agent in a weight ratio of 10:1, and 7% by weight of NaHCO ₃ aqueous solution and 16% by weight of citric acid aqueous solution were sequentially mixed to provide a total of 25 NaHCO ₃ and citric acid aqueous solutions compared to 100% by weight of the dielectric mixture. Make it by weight%. The dielectric composition mixes well with the PDMS polymer and NaHCO ₃ and citric acid to form an emulsion. The dielectric composition for pressure sensors prepared by curing the PDMS polymer by heating the dielectric composition to curing temperatures of 80°C, 90°C, 100°C, 110°C, 120°C, 130°C and 150°C (Scanning Electron Microscopy, SEM) to analyze the pore shape. The dielectric for the pressure sensor is referred to as Comparative Examples 1 to 7 depending on the curing temperature.

4 and 5 are scanning electron microscopy (SEM) photographs showing pores formed on surfaces according to comparative examples of the present invention. 4(a) to 4(g) are SEM photographs of the cross section of the pressure sensor dielectric of Comparative Examples 1 to 7 at 100 times magnification, and FIGS. 5(a) to (g) are Comparative Examples 1 to 7, respectively. This is a SEM photograph of a cross section of a dielectric for a pressure sensor at 1000 times magnification.

4 and 5, pores having a size of 100 μm or more in micrometers are formed in the dielectric for pressure sensors of Comparative Examples 1 to 7, and small pores having a size of 1 μm or more in micrometers of 100 μm or less It can be seen that it is distributed over the entire area. In addition, it can be seen that the lower the curing temperature of the dielectric composition, the smaller the pore size and the uniform distribution.

On the other hand, pores having a micrometer unit size of 100 µm or more may have a high rate of gas when reacting NaHCO ₃ and citric acid when the curing temperature is high, and a large amount of gas is generated before the polymer PDMS is cured. Size increases. Dielectrics having curing temperatures of 120°C, 130°C and 150°C in Comparative Examples 5 to 7 show that the distribution of pores is non-uniform.

On the other hand, in the case of pores having a micrometer unit size of 1 μm or more and 100 μm or less, the pore size is hardly changed according to the curing temperature, but the smaller the curing temperature, the more pores of smaller sizes are distributed and pores within the unit area. It can be seen that the size of is also uniform. This means that the pores of a large size are not formed because the curing temperature is low and the gas is generated at a slow rate, and sufficient time is secured for curing the polymer PDMS.

Figure 6 shows the results of the dielectric constant change experiment of the pressure sensor dielectric according to a comparative example of the present invention.

Using the PDMS dielectric cured at 150°C in Comparative Example 7, the dielectric constant change with respect to external pressure was measured.

Referring to (a) of FIG. 6, the capacitance change rate (ΔC/C ₀ ), which is the amount of change in the dielectric constant (ΔC) with respect to the initial dielectric constant (C ₀ ), is measured according to the intensity of pressure applied from the outside. The external pressure was applied for 3 seconds, then removed again, and repeated experiments.

It can be seen that the dielectric sample of Comparative Example 7 has the same level of capacitance change rate (ΔC/C ₀ ) even when the experiment of applying and removing pressure is repeated. And, it can be seen that when the external pressure is strong, the rate of change in capacitance (ΔC/C ₀ ) also increases. This means that when the pressure sensor is manufactured including Comparative Example 7, it can have the same performance even after repeated use.

Referring to (b) of FIG. 6, when the external pressure is applied to and removed from the dielectric sample of 7 for 3 seconds at an intensity of 15.85 kPa, the rate at which the dielectric constant changes can be seen. When the capacitance change rate (ΔC/C ₀ ) has a value of 0, when an external pressure is applied, it takes less than 300 ms until the capacitance change rate (ΔC/C ₀ ) has the maximum value. This means that the response speed to the external pressure of the dielectric of Comparative Example 7 is very good.

Therefore, the dielectric of the pressure sensor increases the size of pores formed as the curing temperature of the polymer increases, and the dielectric of the pores has an effect of improving durability and sensitivity that can be used as a pressure sensor.

Experimental Example 2

Performance analysis of dielectric for Ecoplex/PDMS pressure sensor

Hereinafter, performance analysis of the dielectric for a pressure sensor using Ecoplex and PDMS as a polymer will be described with reference to FIGS. 7 to 10.

First, PDMS and Ecoflex, which are polymers forming the dielectric for the pressure sensor, will be described.

PDMS is an elastic polymer containing siloxane, and is polydimethylsiloxane. Ecoflex is an elastic polymer polymer, and is classified as polybutyrate (polybutyrate adipate terephthalate, PBAT). Hereinafter, they are called PDMS and Ecoflex, respectively.

In step (a), PDMS and Ecoflex are mixed to prepare a polymer mixture. The two polymers can mix well with each other. Stir using a stick to prepare a uniform mixture. At this time, the mixing ratio can be adjusted, Ecoflex is mixed so that the Ecoflex is 35% by weight, 45% by weight and 55% by weight relative to 100% by weight. This is defined as 35% by weight Ecoflex/PDMS, 45% by weight Ecoflex/PDMS and 55% by weight Ecoflex/PDMS, respectively.

Next, the blowing agent, acidic compound, and surfactant in steps (b) and (c) will be described.

Sodium bicarbonate (NaHCO ₃ ) is used as a blowing agent, citric acid (C ₆ H ₈ O ₇ ) is used as an acidic compound, and sodium dedocylbenzenesulfonate (SDBS) is used as a surfactant. Prepare. Sodium hydrogen carbonate reacts with citric acid to produce CO ₂ gas and H ₂ O. CO ₂ gas can evaporate to form pores on the Ecoflex/PDMS polymer matrix.

Sodium hydrogen carbonate is dissolved in SDBS surfactant and water to prepare an aqueous foaming agent solution. An aqueous foaming agent solution (NaHCO ₃ /SDBS(aq)) is prepared so that the concentrations of sodium hydrogen carbonate and SDBS are 3%, 5% and 7% by weight in total. Then, an aqueous solution of an acidic compound is prepared by dissolving citric acid in SDBS surfactant and water. An aqueous acidic compound solution (citric acid/SDBS(aq)) is prepared so that the concentration of citric acid and SDBS is 70% by weight. The SDBS surfactant is added in a small amount compared to the solute NaHCO ₃ and citric acid. For example, it can be added so that the mass ratio of SDBS: solution is 0.3:100.

The prepared NaHCO ₃ /SDBS(aq) and citric acid/SDBS(aq) contain surfactants to be well dispersed in the Ecoflex/PDMS polymer. When only the PDMS polymer is included, it is well dispersed even without a surfactant, but when more hydrophobic Ecoflex is included, the aqueous solution needs to be dispersed by the surfactant. However, the degree of dispersion differs depending on the concentration of the solute. In the case of citric acid, even when the aqueous solution has a concentration of 70% by weight, the aqueous solution does not cause phase separation and is well dispersed when mixed with the Ecoflex/PDMS polymer, but sodium hydrogen carbonate is 7 Above the concentration of weight percent, the polymer and aqueous solution can cause phase separation.

7 is a photograph showing an aqueous sodium hydrogen carbonate and citric acid solution according to an embodiment of the present invention.

Referring to FIG. 7, it can be seen that sodium bicarbonate and citric acid are well dissolved in water, including SDBS surfactant. It can be seen that when sodium hydrogen carbonate was at a concentration of 7% by weight, the aqueous solution had a slightly bluish color, and all other aqueous solution samples had a transparent color.

Next, a dielectric for a pressure sensor prepared using the Ecoflex/PDMS polymer and NaHCO ₃ /SDBS(aq) and citric acid/SDBS(aq) according to an embodiment of the present invention will be described.

Table 1 below is a table summarizing examples of dielectric compositions for pressure sensors prepared by varying the mixing ratio of Ecoflex/PDMS polymer with NaHCO ₃ /SDBS(aq) and citric acid/SDBS(aq).

sample
Type of Ecoflex/PDMS polymer (weight fraction of Ecoflex, weight %)
NaHCO of dielectric composition ₃ And weight fraction of citric acid aqueous solution (% by weight) Example 1 Ecoflex/PDMS 35% by weight 40% by weight Example 2 Ecoflex/PDMS 35% by weight 50% by weight Example 3 Ecoflex/PDMS 45% by weight 40% by weight Example 4 Ecoflex/PDMS 45% by weight 50% by weight Example 5 Ecoflex/PDMS 55% by weight 40% by weight

Referring to Table 1, in the Ecoflex/PDMS polymer, a sample having Ecoflex of 35% by weight, 45% by weight, and 55% by weight of NaHCO3/SDBS(aq) and citric acid/SDBS(aq) was mixed to prepare a dielectric composition for a pressure sensor. To prepare. In this case, NaHCO3/SDBS(aq) and citric acid/SDBS(aq) compared to 100% by weight of the dielectric composition for the pressure sensor were prepared to be 40% by weight or 50% by weight, respectively, which were defined as Examples 1 to 5.

The performance of the pressure sensor was tested by measuring the rate of change of the capacitance (ΔC/C ₀ ) as in the'Analysis of pores according to the curing temperature'.

First, in order to compare the performance of the dielectric for a pressure sensor according to the curing temperature of the dielectric composition, the dielectric composition of Example 2 is cured at 100°C or 150°C to prepare a dielectric for a pressure sensor, and the rate of change in capacitance (ΔC/C ₀ ) was measured.

Figure 8 shows the experimental results of the capacitance change rate (ΔC/C ₀ ) measurement of the dielectric for a pressure sensor according to an embodiment of the present invention.

8 (a) and (b), the dielectric composition for a pressure sensor prepared by heating the dielectric composition of Example 2 at a curing temperature of 100°C or 150°C is a test for measuring the rate of change of capacitance (ΔC/C ₀ ) It can be seen that the value of the same level as the initial value is maintained even when is repeated. In other words, it can be seen that it exhibits hysteresis because it is durable against pressure changes and contains the elastomer Ecoflex/PDMS. When the curing temperature of the dielectric composition is high, the pores formed in the dielectric for the pressure sensor increase in size, and when comparing (a) and (b) of FIG. 8, the rate of change in capacitance with respect to the applied pressure (ΔC/C ₀ ) The slope of the graph has a large value when the curing temperature is 150°C. This means that the higher the curing temperature, the larger the pore size and the greater the sensitivity to the pressure sensor.

To specifically check this, referring to FIGS. 8(c) and 8(d), in the case of a dielectric for a pressure sensor having a high curing temperature of 150° C., the rate of change in capacitance (ΔC/C ₀ even when a small external pressure is applied) ) Can be seen rising. To quantify this, the slope of the graph of change in capacitance (ΔC/C ₀ ) is calculated. When the curing temperature of the dielectric composition is 100°C and 150°C, the slope of the graph is 0.18/kPa and 0.0099kPa, respectively. Therefore, it can be seen that as the curing temperature of the dielectric composition increases, the size of pores formed in the dielectric for the pressure sensor increases, and the sensitivity increases as the pressure sensor, thereby improving performance.

Next, with reference to FIGS. 9 and 10, the performance analysis of the dielectric for the pressure sensor according to the ratio of the Ecoflex polymer in the polymer of Ecoflex/PDMS and the ratio of NaHCO3/SDBS(aq) and citric acid/SDBS(aq) in the dielectric composition Will be described.

The dielectric composition of Examples 1 to 5 was heated at a curing temperature of 110°C to prepare a dielectric for a pressure sensor, and the compressive strain and the capacitance change rate (ΔC/C ₀ according to the applied compressive stress) ).

9 is a compression stress-compression elongation graph of a dielectric for a pressure sensor according to embodiments of the present invention.

9 (a) to (e), it can be seen that the compressive stress-compression elongation graphs have different curves according to the contents of Ecoflex, NaHCO ₃ and citric acid in the dielectrics for pressure sensors of Examples 1 to 5. . Having a low value of the slope of the curve means that the dielectric strain against stress is large, which means that it has a high sensitivity as a pressure sensor.

9(f), the effect of the contents of Ecoflex, NaHCO ₃ and citric acid in the pressure sensor dielectric on the performance of the pressure sensor will be described.

First, the contents of NaHCO ₃ and citric acid and curing temperature are the same, and the contents of Ecoflex are different from Examples 1 and 5 and Examples 2 and 4 are compared. In both cases, the graph slopes of Examples 1 and 2 with lower Ecoflex content have lower values. This is because PDMS has a higher viscosity than Ecoflex, and when curing the polymer by heating, when the content of Ecoflex decreases, the size of pores due to gas generation increases. Therefore, the lower the Ecoflex content in the Ecoflex/PDMS polymer, the larger the pore size of the dielectric for the pressure sensor and the higher the sensitivity to pressure.

Next, Examples 1 and 2 in which the content of Ecoflex and the curing temperature are the same and the content of NaHCO ₃ and citric acid are different are compared. The graph slope of Example 2 with a higher content of NaHCO ₃ and citric acid has a smaller value. This is because as the proportion of NaHCO ₃ and citric acid increases, the pore size decreases but the density increases. When the density of the pores is increased, the pressure sensor dielectric has a large number of pores, and thus more compression is possible. As the elongation increases, the slope of the graph becomes smaller. That is, the higher the content of NaHCO ₃ and citric acid, the smaller the pore size of the dielectric for the pressure sensor, but the density of the pores increases and the sensitivity to pressure increases.

According to the above embodiments, the lower the content of Ecoflex in the Ecoflex/PDMS polymer, the higher the content of NaHCO ₃ and citric acid in the dielectric composition, and the higher the curing temperature, the higher the change rate of the capacitance of the pressure sensor dielectric (ΔC/C It can be seen that the performance of the pressure sensor is improved by increasing the sensitivity of ₀ ).

10 is a graph showing a result of measuring a rate of change of capacitance (ΔC/C ₀ ) of a dielectric for a pressure sensor according to embodiments of the present invention.

According to Figure 10, the content of the Ecoflex / PDMS polymer is low, the content of Example 2, the content of NaHCO ₃ and citric acid in the dielectric composition is high, 35% by weight Ecoflex/PDMS and NaHCO ₃ and citric acid in a total pressure of 50% by weight It can be seen that the dielectric for the sensor has the largest slope in the graph of the rate of change of capacitance (ΔC/C ₀ ).

Therefore, according to one embodiment of the present invention, a mixture of two different types of polymers with a blowing agent, an acidic compound, and a surfactant can be heated to prepare a dielectric for a pressure sensor, and the mixing ratio of the polymer, a blowing agent and an acidic compound is By adjusting, the performance of the pressure sensor including the dielectric can be improved.

Experimental Example 3

Hereinafter, referring to FIGS. 11 to 29, a mixture of Ecoplex and PDMS as a polymer mixture, sodium bicarbonate (NaHCO ₃ ) as a blowing agent, acetic acid (CH ₃ COOH) as an acidic compound, and sodium as a surfactant Sodium dedocylbenzenesulfonate (SDBS) is prepared to prepare a dielectric for a pressure sensor described with reference to FIGS. 1 and 2.

In the second embodiment, citric acid (C ₆ H ₈ O ₇ ) was used as the acidic compound. In order to overcome the disadvantage that it takes several tens of seconds to recover to the initial capacitance due to viscosity when using citric acid, acetic acid is used as the acidic compound. (CH ₃ COOH).

In this case, when using sodium bicarbonate (NaHCO ₃ ) as the blowing agent and acetic acid (CH ₃ COOH) as the acidic compound, a chemical reaction as shown in Chemical Formula 1 occurs.

[Formula 1]

NaHCO ₃ + CH ₃ COOH → CO ₂ + H ₂ O + NaCH ₃ COO

As in Formula 1, 1 mole of NaHCO _{3 and} 1 mole of CH ₃ COOH react to produce 1 mole of CO _2, so the NaHCO ₃ solution and the CH ₃ COOH solution are uniformly uniform in the elastomer so that the number of moles of NaHCO ₃ 3 and CH ₃ COOH is the same. After mixing, thermal curing was performed to induce pore formation.

Table 2 below is a table summarizing the weight ratio of the ecoflex in the polymer mixture in the third experimental example and the weight ratio of the blowing agent and the acidic compound in the dielectric composition together with the curing temperature.

Ecoflex/(PDMS+Ecoflex)
(NaHCO ₃ +CH ₃ COOH weight) /(PDMS weight + Ecoflex weight + NaHCO ₃ weight + CH ₃ COOH weight)
Curing temperature 70wt% 33wt% 80℃ 70wt% 33wt% 100℃ 70wt% 33wt% 120℃

11 is a scanning electron microscopy (SEM) pictures of a dielectric cross section according to the curing temperature in the third experimental example of the present invention. The upper photos are relatively low magnification photos, and the lower photos are relatively high magnification photos.

Referring to FIG. 11, it can be seen that as the curing temperature of the third experimental example increased to 80°C, 100°C, and 120°C, the pore size increased and the gap between the pores and the pores decreased. It can be seen that in the range of the curing temperature of 80°C to 120°C, the pore size increases and the gap between the pores and the pores decreases as the curing temperature increases. According to these results, it is seen that the curing temperature of 120°C is the best in terms of sensitivity of the pressure sensor. The curing temperature of the Ecoplex and PDMS elastomer mixture is sufficient within 150°C, and the curing temperature of 120°C can be set as an optimal embodiment.

12 is a graph showing a relationship between a pressure sensor dielectric and a capacitance change rate (ΔC/C ₀ ) according to a curing temperature in a third experimental example of the present invention. Referring to FIG. 12, the pressure sensor element was manufactured according to the curing temperature, and measurement was performed. When the curing temperature is 120° C. among 80° C., 100° C., and 120° C., it can be seen that the sensitivity is more than doubled in the entire pressure range. .

13 is a graph showing the relationship between the compressive stress and the compressive strain of the pressure sensor dielectric according to the curing temperature in the third experimental example of the present invention. 13, it can be seen that as the curing temperature increases to 80°C, 100°C, and 120°C, the compressive stress applied when the compressive strain is the same decreases, which decreases the Young's modulus due to pores. Because I did.

14 to 16 are graphs obtained by dividing the sensitivity according to the curing temperature of the pressure sensor dielectric according to the curing temperature according to the pressure range in the third experimental example of the present invention. 14 to 16, it can be seen that in the case of 120°C among the curing temperatures of 80°C, 100°C and 120°C, the sensitivity is best in all pressure ranges.

Table 3 below is a table summarizing the conditions in which the ratio of the pore-forming precursor is varied in a state in which the weight ratio and the curing temperature of Ecoflex in the polymer mixture in the third experimental example are fixed. The ratio of the pore-forming precursor corresponds to the weight ratio of NaHCO ₃ as a blowing agent and CH ₃ COOH as an acidic compound relative to the total weight of the dielectric composition.

Ecoflex/(PDMS+Ecoflex)
(NaHCO ₃ +CH ₃ COOH weight) /(PDMS weight + Ecoflex weight + NaHCO ₃ weight + CH ₃ COOH weight)
Curing temperature 70wt% 0wt% 120℃ 70wt% 28wt% 120℃ 70wt% 33wt% 120℃ 70wt% 38wt% 120℃

17 is a view showing the results of micro-CT analysis of the dielectric for pressure sensors according to the ratio of pore-forming precursors in the third experimental example of the present invention.

Referring to FIG. 17, it can be seen that porosity gradually decreases to 73.614%, 72.533%, and 67.897% as the proportions of pore-forming precursors increase to 28wt%, 33wt%, and 38wt%. As can be seen, it can be seen that the pore size gradually decreases.

18 is a graph showing the relationship between the pressure change rate and the capacitance change rate (ΔC/C ₀ ) of the pressure sensor dielectric according to the pore forming precursor ratio in the third experimental example of the present invention. 19 to 21 are graphs obtained by dividing the sensitivity of the dielectric for the pressure sensor according to the ratio of the pore-forming precursor in the third experimental example of the present invention by pressure range.

18 to 21, since pores are formed by reaction of the blowing agent NaHCO ₃ and the acidic compound CH ₃ COOH, sensitivity is greatly improved in all regions, but as the percentage of pore-forming precursor increases from 28 wt%, the low pressure region is 2 kPa. Below, it can be seen that the sensitivity decreases. Considering this, it can be confirmed that the pore-forming precursor ratio is optimal in terms of sensitivity and uniformity in the case of 33 wt%.

22 is a diagram illustrating an experimental result of evaluating the lowest pressure measurable with a pressure sensor in the third experimental example of the present invention.

Referring to FIG. 22, the capacitance was measured by increasing the number of 10 mg objects in order to know the lowest measurable pressure of the pressure sensor element made of a 33 wt% sensor body in which the pore forming precursor ratio is an optimal embodiment. According to this, it can be confirmed that the lowest pressure measurable by the pressure sensor is 0.915 Pa.

23 is a graph showing the reaction time according to the pressure of the pressure sensor in the third experimental example of the present invention, and FIG. 24 is an enlarged graph of the M1 region of FIG. 23. That is, these graphs are measured to confirm whether the pore-forming precursor ratio is in accordance with the change in the reaction time and pressure of the pressure sensor element made of a 33 wt% sensor body, which is an optimal embodiment.

Referring to FIG. 23, when the reaction time was checked in a state where 0.4 kPa pressure was applied, it was determined that the reaction time was at a level suitable for use as a pressure sensor, as it took 75 ms time, which is the minimum time at the limit of measurement equipment.

25 is a graph showing the reaction time according to the pressure of the pressure sensor in the third experimental example of the present invention, FIG. 26 is an enlarged graph of the M2 region of FIG. 25, and FIG. 27 is an enlarged graph of the M3 region of FIG. 25. to be. In FIG. 25 to FIG. 27, the solid (■, ▲, ●) items correspond to the capacitance change rate (ΔC/C ₀ ), and the hollow (□, △, ○) items correspond to the pressure (kPa). Is the value.

Referring to FIGS. 25 to 27, it can be confirmed whether the capacitance changes according to a change in pressure well with respect to larger pressures. According to this, it can be seen that when the pressure increases or decreases, the capacitance of the device also closely follows the change in pressure.

28 and 29 are graphs showing the reliability evaluation results of the pressure sensor in the third experimental example of the present invention. Here, a pressure sensor element made of a 33 wt% sensor body in which the pore forming precursor ratio is an optimal embodiment was used.

Referring to Figure 28, it can be seen that the device is responding well to real-time pressure change. Referring to Figure 29, the pressure of the device is repeatedly applied to each of about 10000 times for two pressures (25kPa, 50kPa). You can see that the performance is well maintained.

The present invention has been illustrated and described with reference to preferred embodiments, as described above, but is not limited to the above embodiments and is varied by those skilled in the art to which the present invention pertains without departing from the spirit of the present invention. Modifications and modifications are possible. Such modifications and variations should be considered within the scope of the invention and appended claims.

100: dielectric for pressure sensors
200: polymer mixture
210: first polymer
220: second polymer
300: second mixture
310: blowing agent
320: surfactant
350: foaming agent aqueous solution
400: dielectric mixture
410: acidic compound
450: aqueous acidic compound solution
500: pressure sensor
510: dielectric electrode
600: nanowire

Claims (14)

(a) mixing two different first and second polymers to prepare a polymer mixture;
(b) preparing a second mixture by mixing an aqueous solution of a blowing agent in which a blowing agent and a surfactant are dissolved in the polymer mixture;
(c) mixing an acidic compound and an aqueous solution of an acidic compound in which the surfactant is dissolved in the second mixture to prepare a dielectric composition; And
(d) heating the dielectric composition to cure the first polymer and the second polymer;
Including,
In step (b), the blowing agent comprises at least one selected from the group consisting of H ₂ CO ₃ , LiHCO ₃ , NaHCO ₃ , KHCO ₃ , Mg(HCO ₃ ) ₂ and Ca(HCO ₃ ) ₂ ,
In step (c), the acidic compound comprises citric acid (C ₆ H ₈ O ₇ ) or acetic acid (CH ₃ COOH),
Method for manufacturing dielectric for pressure sensors. According to claim 1,
In step (a), the first polymer and the second polymer are at least any one selected from the group consisting of polybutyrate, polyurethane, and polydimethylsiloxane (PDMS), respectively. Manufacturing method of dielectric. delete (a) mixing two different first and second polymers to prepare a polymer mixture;
(b) preparing a second mixture by mixing an aqueous solution of a blowing agent in which a blowing agent and a surfactant are dissolved in the polymer mixture;
(c) mixing an acidic compound and an aqueous solution of an acidic compound in which the surfactant is dissolved in the second mixture to prepare a dielectric composition; And
(d) heating the dielectric composition to cure the first polymer and the second polymer; Including,
In the step (c), the weight ratio of the blowing agent and the acidic compound in the dielectric composition is 25wt% to 40wt%,
In the step (d), characterized in that the heating is performed at 80 ℃ to 150 ℃,
Method for manufacturing dielectric for pressure sensors. (a) mixing two different first and second polymers to prepare a polymer mixture;
(b) preparing a second mixture by mixing an aqueous solution of a blowing agent in which a blowing agent and a surfactant are dissolved in the polymer mixture;
(c) mixing an acidic compound and an aqueous solution of an acidic compound in which the surfactant is dissolved in the second mixture to prepare a dielectric composition; And
(d) heating the dielectric composition to cure the first polymer and the second polymer;
Including,
In at least one of the steps (c) to (d),
The foaming agent and the acidic compound react to produce a gas, characterized in that the gas to form pores in the polymer mixture, a method for producing a dielectric for a pressure sensor. The method of claim 5,
Among the first polymer and the second polymer, the higher the content of the polymer having a relatively high viscosity, the higher the content of the blowing agent, the higher the content of the acidic compound, the larger the pore size, the pressure of the dielectric Characterized by an increased sensitivity to,
Method for manufacturing dielectric for pressure sensors. A polymer mixture in which two different first and second polymers are mixed is used as a matrix,
A pore is formed in the polymer mixture matrix, and the pore is formed in the polymer mixture matrix by a gas generated by reaction of a blowing agent and an acidic compound.
Dielectric for pressure sensors. The method of claim 7,
Each of the first polymer and the second polymer is at least one selected from the group consisting of polybutyrate, polyurethane, and polydimethylsiloxane (PDMS),
Dielectric for pressure sensors. delete The method of claim 7,
The blowing agent includes at least one selected from the group consisting of H ₂ CO ₃ , LiHCO ₃ , NaHCO ₃ , KHCO ₃ , Mg(HCO ₃ ) ₂ and Ca(HCO ₃ ) ₂ ,
The acidic compound comprises citric acid (C ₆ H ₈ O ₇ ) or acetic acid (CH ₃ COOH),
Dielectric for pressure sensors. Upper and lower electrodes spaced apart from each other; And
A dielectric material for a pressure sensor interposed between the upper electrode and the lower electrode, wherein a polymer mixture in which two different types of the first polymer and the second polymer are mixed is used as a matrix, and pores are formed in the polymer mixture matrix. ;
The pores are characterized in that formed in the polymer mixture matrix by the gas generated by the reaction of the blowing agent and the acidic compound,
Capacitive pressure sensor. The method of claim 11,
Each of the first polymer and the second polymer is at least one selected from the group consisting of polybutyrate, polyurethane, and polydimethylsiloxane (PDMS),
Capacitive pressure sensor. delete The method of claim 11,
The blowing agent includes at least one selected from the group consisting of H ₂ CO ₃ , LiHCO ₃ , NaHCO ₃ , KHCO ₃ , Mg(HCO ₃ ) ₂ and Ca(HCO ₃ ) ₂ ,
The acidic compound comprises citric acid (C ₆ H ₈ O ₇ ) or acetic acid (CH ₃ COOH),
Capacitive pressure sensor.

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