KR102143529B1 - Highly sensitive balloon typed sensor - Google Patents

Abstract

Disclosed is a high-sensitivity balloon-type sensor. The balloon-type sensor includes a balloon-type membrane body having a balloon-type structure having a closed space for accommodating gas therein; A strain sensor attached to a surface of the balloon-shaped membrane body and sensing an external force applied to the balloon-shaped membrane body through a change in resistance; And a resistance change measuring device for measuring a change in resistance of the strain sensor.

Description

High sensitivity balloon type sensor {HIGHLY SENSITIVE BALLOON TYPED SENSOR}

The present invention relates to a highly sensitive balloon-type sensor that can be applied to a soft robot.

As the technology for robots advances and the contribution of robots to human life increases, there is an increasing demand for robots that are formed of flexible and soft materials and are capable of safe interaction with humans. For example, traditional robots are very difficult to implement functions such as picking up soft materials, but soft robots can easily achieve these functions. The robotic arm, which can be inflated by air injection, has shown potential such as low cost, light weight and safe collision.

Most of these soft robots, which have structures that can be inflated by air injection, operate and are controlled based on pressure data from pressure sensors. However, most of the conventional pressure sensors require tubes to be connected to the soft robot, and since traditional pressure sensors are hard elements that are difficult to be easily applied to soft materials, an additional space is required for the pressure sensor and connection tubes to be installed. .

There is a need to develop a sensor for a soft robot that can solve the problem of these traditional pressure sensors.

It is an object of the present invention to provide a balloon-type sensor that can detect very high sensitivity of an external force and can be easily applied to a soft robot.

A balloon-type sensor according to an embodiment of the present invention includes a balloon-type membrane body having a balloon-type structure having a closed space for accommodating gas therein; A strain sensor attached to a surface of the balloon-shaped membrane body and sensing an external force applied to the balloon-shaped membrane body through a change in resistance; And a resistance change meter measuring a change in resistance of the strain sensor.

In one embodiment, the strain sensor is a support film attached to the outer surface of the balloon-type membrane body; And a resistance change layer formed on the support film. For example, the resistance change layer may include one or more metal thin films into which cracks are introduced.

In one embodiment, the balloon-type membrane body may be formed of a first polymer material, and the support film may be formed of a second polymer material having an expansion coefficient equal to or greater than that of the first polymer material. For example, the first polymer material may include polyethylene or polyimide, and the second polymer material may include polyethylene, polyimide, silicone rubber or urethane rubber.

In one embodiment, the balloon-type membrane body may have a thickness of 50 to 100 μm, and the support film may have a thickness of 5 to 20 μm.

In one embodiment, the support film has a width in a first direction and a length in a second direction orthogonal to the first direction, the length is greater than the width, and the support film is in the second direction. Both end portions of the balloon may be attached to the inflatable membrane body.

In one embodiment, the strain sensor is attached to the balloon-type membrane body in a state in which wrinkles are introduced in a region under the strain sensor before the gas is injected into the balloon-type membrane body, and inside the balloon-type membrane body In a state in which the gas is injected, a tension caused by pressure inside the balloon-type membrane body may be applied to the strain sensor. For example, by the tension, the surface area of the support film may increase from about 0.00001% to 1000% compared to the initial period.

In one embodiment, the internal pressure of the inflatable membrane body may be 1 to 1 MPa.

In one embodiment, the balloon-type sensor may sense an impact of an object on the balloon-type membrane body and a vibration of the balloon-type membrane body caused by the impact.

According to the high-sensitivity balloon-type sensor of the present invention, an external force applied to almost all areas of the balloon-type membrane body can be sensed very highly sensitively, so that it can be easily applied to a soft robot.

1 is a plan view illustrating a high-sensitivity balloon-type sensor according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along the cutting line A-A' shown in FIG. 1.
3 is a cross-sectional view for explaining the structure of a high-sensitivity balloon-type sensor according to an embodiment of the present invention.
4 is a view for explaining a method of manufacturing the balloon-type sensor of Examples 1 to 3.
5A is a photograph of a balloon-type sensor manufactured according to the method shown in FIG. 4, and FIG. 5B is a diagram illustrating a measurement system for an experiment.
6 is a graph showing a change in resistance to an external force measured for the balloon-type sensor of Examples 1 to 3.
7 is a graph showing a change in resistance to an external force measured for the inflatable sensor of Example 3 and the conventional pressure sensor (MPX5100ap).
8 is a graph showing a change in resistance to an external force measured while changing a position to which an external force is applied to the balloon-type sensor of Example 1. FIG.
9 is a graph showing a change in resistance according to time measured after applying an external force (2N, 4N, 8N, 12N) to a point 6cm away from the strain sensor in the balloon-type sensor of Example 1. FIG.
10 is a graph showing the result of measuring the response speed to an external force of 8N for the balloon-type sensor of Example 1.
11 is a graph showing a change in resistance over time measured after dropping an object (2.2g, 1.0g, 0.4g, 0.2g) from a height of 30cm for the balloon-type sensor of Example 1. FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention can be applied to various changes and may have various forms, and specific embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to specific disclosure forms, and it should be understood that all modifications, equivalents, and substitutes included in the spirit and scope of the present invention are included. In describing each drawing, similar reference numerals are used for similar components. In the accompanying drawings, the dimensions of the structures are shown to be enlarged than actual in order to clarify the present invention.

Terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, terms such as “include” or “have” are intended to indicate that a feature, number, step, action, component, or combination thereof, described in the specification exists, one or more other features or numbers. It should be understood that it does not preclude the existence or addition possibility of steps, steps, elements, or combinations thereof.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms, such as those defined in a commonly used dictionary, should be interpreted as having meanings consistent with meanings in the context of related technologies, and should not be interpreted as ideal or excessively formal meanings unless explicitly defined in the present application. Does not.

1 is a plan view for explaining a high-sensitivity balloon-type sensor according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line A-A' shown in FIG. 1.

1 and 2, the high-sensitivity balloon-type sensor 100 according to an embodiment of the present invention includes a balloon-type membrane body 110, a strain sensor 120, and a resistance change meter 130.

The balloon-shaped membrane body 110 may have a balloon-shaped structure having a closed space for accommodating a gas such as air therein. The inner space of the balloon-type membrane body 110 may be filled with gas to have a preset pressure, and when an external force is applied to the surface of the balloon-type membrane body 110, the inner space is deformed by the internal pressure. The resistance of the strain sensor 120 may be changed.

If an inner space that can be deformed by an external force applied to the surface is provided, the shape of the balloon-type membrane body 110 is not particularly limited. For example, the balloon-type membrane body 110 may have a cylindrical shape that extends long in one direction, or may have a spherical shape or an atypical shape, and may be variously changed as necessary.

In one embodiment, the balloon-type membrane body 110 may be formed of a polymer material having a relatively low coefficient of expansion and a constant stiffness. For example, the balloon-shaped membrane body 110 may be formed of a material such as polyethylene (PE) or polyimide (PI). If the balloon-shaped membrane body 110 is formed of a material such as silicone or urethane having a relatively high coefficient of expansion, the relationship between the resistance change of the strain sensor 120 and the magnitude of the external force is modeled. Problems can arise.

In one embodiment, while providing relatively stable structural strength, the balloon-type membrane body 110 is a polymer having a thickness of about 50 to 100 μm so that the inner space can be deformed by the internal pressure even with a slight external force. It can be formed into a film.

The strain sensor 120 may be attached to the outer surface of the balloon-type membrane body 110, and an external force applied to the balloon-type membrane body 110 through a change in resistance and the balloon-type membrane caused thereby Vibrations of the body 110 may be detected. For example, when an external force is applied to the surface of the balloon-type membrane body 110, the internal space of the balloon-type membrane body 110 is deformed by the external force, and the deformation of the internal space is the strain. It may cause a change in resistance of the sensor 120.

In one embodiment, the strain sensor 120 may include a highly sensitive crack sensor. In this case, the strain sensor 120 may include a support film 121 and a resistance change layer 122 formed on the support film 121.

The support film 121 may be attached to the outer surface of the inflatable membrane body 110. The support film 121 may have a rectangular shape having a certain length and width, and the area of the support film 121 may be appropriately adjusted as necessary.

In one embodiment, in order to improve the sensitivity of the high-sensitivity balloon-type sensor 100, the support film 121 may be formed as thin as possible, for example, to a thickness of about 5 to 20 μm, and Only both ends may be attached to the outer surface of the balloon-type membrane body 110 by the adhesive 123.

In one embodiment, the support film 121 may be formed of the same material as the polymer material constituting the balloon-type membrane body 110 or a polymer material having a higher expansion coefficient. For example, the support film 121 may be formed of a material such as polyimide, polyethylene, silicone rubber, or urethane rubber.

The resistance change layer 122 may be disposed on the support film 121 and may include one or more metal thin films into which cracks are introduced. For example, the resistance change layer 122 may include a stacked chromium (Cr) thin film and a gold (Au) thin film.

3 is a cross-sectional view illustrating the structure of a high-sensitivity balloon-type sensor according to an embodiment of the present invention.

Referring to FIG. 3 along with FIGS. 1 and 2, in order to improve the sensitivity of the high-sensitivity balloon-type sensor 100, before injecting gas into the balloon-type membrane body 110, the balloon-type membrane body 110 ), in the process of attaching the strain sensor 120 to the balloon-type membrane body 110, in a state in which a wrinkle is introduced into a region under the strain sensor 120 of the balloon-type membrane body 110, the strain sensor 120 It may be attached to the type membrane body 110. In this case, when gas is injected into the balloon-type membrane body 110, a greater tension is applied to the strain sensor 120 by the internal pressure of the balloon-type membrane body 110, and as a result, the high-sensitivity balloon-type sensor The sensitivity of (100) can be improved. In one embodiment, in a state in which air is injected into the balloon-type membrane body 110, the area under the strain sensor 120 increases so that the surface area of the support film 121 increases by about 0.00001% to 1000% compared to the initial stage. Wrinkles may be introduced into the For example, in a state in which air is injected into the balloon-type membrane body 110, the surface area of the support film 121 increases by about 1 to 100%, about 5 to 80%, or about 10 to 50% compared to the initial stage. A wrinkle may be introduced into a region under the strain sensor 120.

If the surface area increase ratio of the support film 121 is less than 0.00001% compared to the initial period, there is a problem that it does not contribute to the sensitivity improvement, and if it exceeds 1000%, the sensitivity may be decreased.

The resistance change meter 130 may be electrically connected to the strain sensor 120 to measure a change in resistance of the strain sensor 120. For example, when the strain sensor 120 is a cran sensor, the resistance change meter 130 is electrically connected to a point spaced apart from each other of the resistance change layer 122 to determine the resistance of the resistance change layer 122. Change can be measured.

As long as the resistance change of the strain sensor 120 can be measured, the structure and shape of the resistance change meter 130 are not particularly limited.

According to the high-sensitivity balloon-type sensor of the present invention, an external force applied to almost all areas of the balloon-type membrane body can be sensed very highly sensitively, so that it can be easily applied to a soft robot.

Hereinafter, examples and experimental examples of the present invention will be described in detail. However, the following examples are only one embodiment of the present invention, and the scope of the present invention is not limited to the following examples.

[Examples 1 to 3]

As shown in FIG. 4, three balloon-type sensors having different internal pressures were manufactured.

First, a crack sensor was manufactured as shown in (b) of FIG. 4. To manufacture the crack sensor, after attaching a 7.5 µm-thick polyimide (PI) film on a glass substrate coated with PDMS, plasma treatment was performed on the PI film to improve adhesion to the metal film, and then PI A 50 nm-thick chromium (Cr) layer and a 30 nm-thick gold (Au) layer were sequentially deposited on the film, and 2% of the initial length was used to introduce cracks in the chromium (Cr) layer and the gold (Au) layer. Stretched.

Subsequently, a balloon-type membrane body having a width of 6 cm and a length of 17 cm was formed as shown in FIG. 4A. To form the balloon-shaped membrane body, two LDPE (low-density polyethylene) films having a thickness of 80 μm are laminated and heat is applied along a preset line to heat-bond the two LDPE films along the line. Then, the balloon-type membrane body was manufactured by cutting it.

Then, the crack sensor was attached to the balloon-type membrane body using an adhesive. At this time, only both end regions of the crack sensor were attached to the balloon-type membrane body, thereby preventing a decrease in sensitivity of the sensor by forming an adhesive layer between the crack sensor and the balloon-type membrane body.

Subsequently, after connecting both ends of the crack sensor to a resistance meter using a wire, air was injected into the balloon-type membrane body to produce a balloon-type sensor. At this time, air was injected so that the initial pressure inside the balloon-type membrane body was 2 kPa (Example 1), 5 kPa (Example 2), and 8 kPa (Example 3).

Figure 5a shows a photograph of the manufactured balloon-type sensor, Figure 5b is a diagram showing a measurement system for the experiment.

[Experimental Example]

6 is a graph showing a change in resistance to an external force measured for the balloon-type sensor of Examples 1 to 3. At this time, an external force was applied to a position 6 cm apart from the crack sensor on the surface of the balloon-type membrane body.

Referring to FIG. 6, the change in resistance was observed to increase most rapidly when the initial pressure was 2 kPa, and it was found that the resistance change was the smallest in the sensor having an internal pressure of 8 kPa.

From this, it can be confirmed that the balloon-type sensor exhibits different response characteristics to external forces of the same magnitude according to the pressure inside the balloon. This means that the net force acting on the surface of the balloon corresponds to the difference between the external force and the internal force caused by the internal pressure of the balloon, and as a result, for the same magnitude of return force, the lower the internal pressure, the more It is believed that this is because many balloons are deformed.

From this, it can be seen that the sensitivity of the balloon-type sensor can be adjusted by controlling the internal pressure of the balloon-type membrane body.In order to manufacture a high-sensitivity balloon-type sensor, the internal pressure of the balloon-type membrane body is preferably about 1 to 3 kPa. Do.

7 is a graph showing a change in resistance to an external force measured for the inflatable sensor of Example 3 and the conventional pressure sensor (MPX5100ap).

Referring to FIG. 7, in the conventional pressure sensor, the resistance change did not appear until the external force became 1.5N or more, and thus it could not be detected. However, the balloon-type sensor of Example 3 was very It has been shown that even small external forces can be detected.

8 is a graph showing a change in resistance to an external force measured while changing a position to which an external force is applied to the balloon-type sensor of Example 1. FIG. At this time, the external force was applied to a location separated by 2.5cm, 5cm, 6cm, and 7cm from the crack sensor.

Referring to FIG. 8, it was found that a similar resistance change was caused for the same external force even if the location where the external force was applied was changed except for the case where the external force was applied to a location 2.5 cm apart from the crack sensor.

The minute difference between the output signals at 5cm, 6cm, 7cm apart is considered to be due to the difference in internal pressure due to the air permeability of the LDPE film, and external force is applied when the balloon-type membrane body is manufactured with a material having low air permeability. It is determined that it is possible to prevent the difference in the output signal according to the location of the device.

From the above results, it can be seen that in the balloon-type sensor of the present invention, the entire area of the balloon-type membrane body surface, excluding a location very close to the crack sensor, may be the detection area. That is, the balloon-type sensor of the present invention can detect an external force at a frozen position of the balloon-type membrane body, unless the distance from the crack sensor is too close and surface deformation caused by an external force directly affects the strain sensor. have.

9 is a graph showing a change in resistance according to time measured after applying an external force (2N, 4N, 8N, 12N) to a point 6cm away from the strain sensor in the balloon-type sensor of Example 1. FIG.

Referring to FIG. 9, it was found that the resistance change with respect to external force was stably generated and there was almost no noise. The change in resistance was found to increase non-linearly with the increase of the external force, which is believed to be due to the nonlinearity in the resistance change of the crack sensor.

From the above results, it can be seen that the balloon-type sensor of the present invention can stably detect even a small force.

10 is a graph showing the result of measuring the response speed to an external force of 8N for the balloon-type sensor of Example 1.

Referring to FIG. 10, it can be seen that the balloon-type sensor of Example 1 generates an output response almost immediately to an external force.

11 is a graph showing a change in resistance over time measured after dropping an object (2.2g, 1.0g, 0.4g, 0.2g) from a height of 30cm for the balloon-type sensor of Example 1. FIG.

Referring to FIG. 11, it can be seen that the balloon-type sensor of Example 1 can detect not only the impact of an object on the balloon-type membrane body, but also vibration of the balloon-type membrane body caused by the impact. It was found that the conventional pressure sensor (MPX5100ap) cannot detect any impact under the same conditions.

Although the above has been described with reference to preferred embodiments of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the present invention described in the following claims. You will understand that you can.

100: balloon sensor 110: balloon membrane body
120: strain sensor 130: resistance change meter

Claims (11)

A balloon-type membrane body having a balloon-shaped structure having a closed space for accommodating gas therein;
A strain sensor attached to a surface of the balloon-type membrane body and sensing an external force applied to the balloon-type membrane body through a change in resistance; And
Including a resistance change measuring device for measuring the resistance change of the strain sensor,
The strain sensor may include a support film attached to the outer surface of the inflatable membrane body; And a resistance change layer having one or more metal thin films into which cracks attached to the support film are introduced,
The support film has a width in a first direction and a length in a second direction orthogonal to the first direction, the length is greater than the width, and the support film has only both end portions of the second direction A balloon-type sensor, characterized in that attached to the balloon-type membrane body. delete delete The method of claim 1,
The balloon-type membrane body is formed of a first polymer material, and the support film is formed of a second polymer material having an expansion coefficient equal to or greater than that of the first polymer material. The method of claim 4,
The first polymer material comprises polyethylene or polyimide, and the second polymer material comprises polyethylene, polyimide, silicone rubber or urethane rubber. The method of claim 1,
The balloon-type membrane body has a thickness of 50 to 100 μm, and the support film has a thickness of 5 to 20 μm.
delete The method of claim 1,
The support film of the strain sensor is attached to the balloon-type membrane body only at both end portions in a state in which wrinkles are introduced in the region under the strain sensor before the gas is injected into the balloon-type membrane body,
In a state in which the gas is injected into the balloon-type membrane body, a tension caused by pressure inside the balloon-type membrane body is applied to the strain sensor. The method of claim 8,
The balloon-type sensor, characterized in that the surface area of the support film increases by 0.00001% to 1000% compared to the initial period by the tension. The method of claim 1,
The balloon-type sensor, characterized in that the internal pressure of the balloon-type membrane body is 1 to 1 MPa. The method of claim 1,
A balloon-type sensor, characterized in that for detecting an impact of an object on the balloon-type membrane body and a vibration of the balloon-type membrane body caused by the impact.

Images