JP6753980B2 - Wearable sensor and sensor system - Google Patents

Description

The present invention relates to a wearable sensor that is a sensor device that detects an arbitrary physical quantity and that can be worn and carried by a person.

With the development of sensor networks in recent years, attention has been paid to sensor elements that can be used by anyone at any time. In particular, the integration of sensors and processing calculation functions into clothing is called "wearable computing" and is attracting attention.
So far, as a wearable sensor device, for example, a device in which a strain gauge is attached to clothes has been proposed (Patent Document 1).

On the other hand, in recent years, attention has been paid to metamaterial technology using a minute resonance structure. This technology can control the effective magnetic permeability and dielectric constant felt by electromagnetic waves by selecting the shape and material of the resonator. Since the effective permittivity and magnetic permeability are greatly affected by the shape and electrical characteristics of the minute resonant structure, sensing applications can be made by utilizing the changes in the shape and electrical characteristics of the resonator. As for such a sensor, a distortion sensor formed on a flexible substrate and the like have been reported (Non-Patent Document 1).

Japanese Unexamined Patent Publication No. 2011-047702

R. Melik et al., "Metamaterial based telemetric strain sensing in different materials", 1 March 2010, Vol. 18, No. 5, OPTICS EXPRESS 5O

However, in such a conventional technique, since it is necessary to wear a semiconductor device or a flexible substrate on clothes, there is a strong sense of aesthetic and appearance resistance due to lack of unity between the clothes and the sensor, and the behavior of the living body is restricted. The current situation is that the spread is not progressing because there are issues such as.

An object of the present invention is to solve such a problem, and an object of the present invention is to provide a wearable sensor capable of realizing a wearable sensor device using only fibers without significantly impairing the appearance and appearance of clothes.

In order to achieve such an object, the wearable sensor according to the present invention is a wearable sensor used in a sensor system that measures a specific physical quantity based on a comparison result of transmitted and received electromagnetic waves, and is a non-conductive base cloth. It is formed of a conductive medium to includes a control system which changes the electromagnetic waves incident by resonating the input and shines electromagnetic wave, a resonant structure for changing the degree of change with respect to the electromagnetic wave by deformation in accordance with the physical quantity ..

Further, examples of the configuration of such the wearable sensor in the present invention, among the resonant structure, the resonant structure formed of a conductive medium, split ring structure, dipole structure, cross-dipole structure, fishnet structure or mushrooms, It is a structure.

Further, in one configuration example of the wearable sensor according to the present invention, among the resonance structures, the resonance structure formed by the conductive fibers is formed by weaving the conductive fibers into the base cloth. Is.

Further, in one configuration example of the wearable sensor according to the present invention, among the resonance structures, the resonance structure formed by the conductive medium is formed by applying the conductive medium to the base cloth. It is a thing.

Further, in one configuration example of the wearable sensor according to the present invention, among the resonance structures, the resonance structure formed by cutting out the conductive base cloth is a split ring structure, a dipole structure, a cross dipole structure, a fishnet structure, and the like. Or it has an open ring structure.

Further, the sensor system according to the present invention transmits and receives electromagnetic waves to any of the above-mentioned wearable sensors, and measures a specific physical quantity based on a comparison result between the transmitted electromagnetic waves and the received electromagnetic waves.

According to the present invention, a wearable sensor device can be realized by a conductive fiber or a conductive medium formed on a non-conductive base cloth, or a notch formed on the conductive cloth. Therefore, it is not necessary to wear the semiconductor device or the flexible substrate on the clothes, and the sensor device can be attached to the living body without significantly impairing the aesthetic appearance and appearance of the clothes and without restricting the behavior of the living body. Therefore, the sensor device and the sensor system using the sensor device can be widely used.

It is explanatory drawing which shows the structure of the wearable sensor (split ring structure) which concerns on 1st Embodiment. It is explanatory drawing which shows the distortion of a resonance structure. It is explanatory drawing which shows the change of the dielectric constant of a base cloth. It is a graph which shows the transmission characteristic of a resonance structure. This is a configuration example of a sensor system (reflection type). This is a configuration example of a sensor system (shared antenna type). This is a configuration example of a sensor system (transmissive type). It is explanatory drawing which shows the structure of the wearable sensor (dipole structure) which concerns on 2nd Embodiment. It is explanatory drawing which shows the structure of the wearable sensor (cross-dipole structure) which concerns on 2nd Embodiment. It is explanatory drawing which shows the structure of the wearable sensor (fish net structure) which concerns on 3rd Embodiment. It is explanatory drawing which shows the structure of the wearable sensor (mushroom structure) which concerns on 3rd Embodiment. It is explanatory drawing which shows the structure of the wearable sensor (cutout split ring structure) which concerns on 4th Embodiment. It is explanatory drawing which shows the structure of the wearable sensor (notch cross dipole structure) which concerns on 4th Embodiment. It is explanatory drawing which shows the structure of the wearable sensor (notch open ring structure) which concerns on 4th Embodiment. It is explanatory drawing which shows the structure of the wearable sensor (composite type) which concerns on 5th Embodiment.

Next, an embodiment of the present invention will be described with reference to the drawings.
[First Embodiment]
First, the wearable sensor 10 according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is an explanatory diagram showing a configuration of a wearable sensor (split ring structure) according to the first embodiment.

The wearable sensor 10 is composed of a resonance structure 11 formed of conductive fibers on the front surface, the back surface, or the inner layer of the non-conductive base cloth 12 and changing the electromagnetic wave by resonating with the incident electromagnetic wave. .. In the example of FIG. 1, the resonance structure 11 has a split ring structure as a whole, more specifically, a substantially C-shape in a plan view, and a plurality of resonance structures 11 are arranged on the base cloth 12. The resonance structure 11 is formed to have a size shorter than the wavelength of the electromagnetic wave.

Specific examples of the non-conductive fibers constituting the base cloth 12 include synthetic fibers such as polyester and acrylic. The resonance structure 11 may be formed, for example, by sewing a thread of a conductive fiber into the base cloth 12. Further, the resonance structure 11 may be formed by selectively applying a conductive medium made of a conductive solution or resin to the base cloth 12.

Since the resonance structure 11 is electrically equivalent to a fine LC resonator, the effective magnetic permeability value fluctuates greatly in the vicinity of the resonance point. Although the wearable sensor 10 can be composed of one resonance structure 11, it may be composed of a plurality of resonance structures 11, and the measurement sensitivity increases as the number of resonance structures 11 increases.

In general, the length of the resonator does not exceed the wavelength, so it is desirable that the resonance structure has a size smaller than the wavelength. The specific size of the resonance structure 11 may be determined so that resonance occurs at the wavelength of the input electromagnetic wave. For example, in the case of a C-type resonance structure as shown in FIG. 1, the resonance frequency fr is described by the following equation (1) using the effective reactance L and the effective capacitance C of the resonator. ..

In general, increasing the resonator size increases the L value, so lowering the C value of the resonator (that is, widening the separation width of the C-shape, using a donation with a small dielectric constant, etc.) will increase the size of the resonator. The resonance frequency can be made constant while increasing. The same applies when the size of the resonator is reduced. However, since there are restrictions on the dielectric constant of the material and the size of the resonator that can be manufactured with high accuracy, it is necessary to select a suitable resonator size in consideration of the above.

FIG. 2 is an explanatory diagram showing distortion of the resonance structure. Since the resonance structure 11 is formed of conductive fibers, distortion occurs due to expansion and contraction of the base cloth 12. For example, when the base cloth 12 is pulled by the movement of a living body, the resonance structure 11 is subjected to tensile strain as shown in FIGS. 2 (a) to 2 (b), and the shape of the resonance structure 11 changes. Therefore, the electrical characteristics of the conductive fiber, such as dielectric constant, magnetic permeability, and electrical resistance, change.

FIG. 3 is an explanatory diagram showing a change in the dielectric constant of the base fabric. The permittivity ε of the base cloth 12 changes depending on the electric susceptibility χ and the ambient temperature T of the base cloth 12 with reference to the permittivity ε _{0 of the} vacuum, and is obtained by ε = ε ₀ + χT. Therefore, when the ambient temperature T changes and the dielectric constant of the base cloth 12 changes, the electrical characteristics of the conductive fibers also change.

FIG. 4 is a graph showing the transmission characteristics of the resonance structure. Here, with respect to the resonance structure 11 having a substantially C-shaped plan view shown in FIG. 1, the result of measuring the transmission parameter (S12) in the case of the presence or absence of tensile distortion is displayed in a graph. A peak is seen in the transmission parameter in both the characteristics with and without distortion, and it can be seen that the LC resonance frequency corresponding to the peak shifts depending on whether there is distortion or not.

Therefore, the intensity, phase, and polarization state of the electromagnetic wave reflected by the resonance structure 11 or transmitted through the resonance structure 11 changes according to the deformation of the resonance structure 11 due to, for example, tensile strain. By measuring and calculating the relationship between the change in the electromagnetic wave and the distortion of the resonance structure 11 in advance, it is possible to estimate the distortion of the resonance structure 11 from the measured change in the electromagnetic wave.

Here, the case where the wearable sensor 10 is used as a distortion sensor for detecting distortion has been described as an example, but the present invention is not limited to this. For example, when detecting the temperature, the base cloth 12 or the conductive fiber having a large shrinkage change with the temperature is selected, and the material of the base cloth 12 or the conductive fiber and the shape of the resonance structure 11 are selected according to the physical quantity to be measured. , Parameters such as the arrangement direction and the spacing of the resonance structure 11 may be arbitrarily selected.

Further, when a split ring structure, that is, a substantially C-shaped shape in a plan view is selected as the shape of the resonance structure 11, the shape is not a point control because there is an opening, but from the measurement result, the opening of the opening with respect to the incident direction of the electromagnetic wave. It was found that the orientation could be any direction. If the shape of the resonance structure 11 has a split ring structure in which a part of the substantially ring shape in a plan view is cut out, electrical characteristics equivalent to those of an LC resonator can be obtained. Therefore, the substantially C-shaped shape in plan view is composed of a curved line as a whole, but the curved line may be formed in a straight line, for example, a substantially U-shaped shape in plan view.

FIG. 5 is a configuration example of a sensor system (reflection type). The sensor system 1 receives a high-frequency oscillator 21 that generates a high-frequency signal, a transmitting antenna 22 that transmits an electromagnetic wave composed of a high-frequency signal from the high-frequency oscillator 21 toward the wearable sensor 10, and an electromagnetic wave reflected by the wearable sensor 10. It is composed of a receiving antenna 23 and a measuring device 24 for measuring a change in the electromagnetic wave in the wearable sensor 10 by a high frequency signal indicating an electromagnetic wave received by the receiving antenna 23.

FIG. 6 is a configuration example of a sensor system (antenna shared type). In this sensor system 1, the transmission / reception of electromagnetic waves is shared by one transmission / reception antenna 25, and the transmission / reception antenna 25 is a high-frequency oscillator via an isolator 26 for separating a high-frequency signal for transmission and a high-frequency signal for reception. It is connected to 21 and the measuring device 24.

FIG. 7 is a configuration example of a sensor system (transmissive type). The sensor system 1 is the same as the reflection type configuration of FIG. 4 except that the receiving antenna 23 is arranged at a position where the receiving antenna 23 receives the electromagnetic wave transmitted through the wearable sensor 10.

[Second Embodiment]
Next, the wearable sensor 10 according to the second embodiment of the present invention will be described with reference to FIGS. 8 and 9. FIG. 8 is an explanatory diagram showing a configuration of a wearable sensor (dipole structure) according to the second embodiment. FIG. 9 is an explanatory diagram showing a configuration of a wearable sensor (cross dipole structure) according to the second embodiment.

When the split ring structure (FIG. 1) described in the first embodiment is selected as the shape of the resonance structure 11, resonance may not occur when an electromagnetic wave is incident on the base cloth 12 from a specific direction. .. This is because, depending on the incident direction of the electromagnetic wave, the magnetic field component of the electromagnetic wave may not be formed so as to penetrate the resonance structure 11 or intersect the resonance structure 11.

In the example of FIG. 8, the resonance structure 11 is formed in a straight line, that is, in a substantially I-shape in a plan view, along the cloth plane of the base cloth 12. As a result, for example, even if an electromagnetic wave is incident from a direction perpendicular to the base cloth 12, resonance is obtained, which is an excellent effect. This is because resonance occurs if the electric field of the electromagnetic wave exists in the extending direction of the dipole.

The structure shown in FIG. 8 has a dependency on incident polarization, but it depends on polarization by taking a cross-dipole structure in which the dipole structures intersect as shown in FIG. 9, that is, a substantially cross shape in a plan view. An excellent effect of eliminating sex can be obtained.

[Third Embodiment]
Next, the wearable sensor 10 according to the third embodiment of the present invention will be described with reference to FIGS. 10 to 11. FIG. 10 is an explanatory diagram showing a configuration of a wearable sensor (fishnet structure) according to the third embodiment. FIG. 11 is an explanatory diagram showing a configuration of a wearable sensor (mushroom structure) according to the third embodiment.

As the shape of the resonance structure 11, the split ring structure (FIG. 1) described in the first embodiment, the dipole structure (FIG. 8) and the cross dipole structure (FIG. 9) described in the second embodiment are selected. In that case, there is a problem that the transmitted electromagnetic wave is incident on the living body.
In order to prevent this, it is desirable that all the electromagnetic waves incident on the resonance structure 11 are reflected and the phase and polarization state of the reflected waves change.

The fishnet structure in which conductive fibers are arranged in a mesh pattern as shown in FIG. 10 and the mushroom structure as shown in FIG. 11 reflect all electromagnetic waves incident on the resonance structure 11 and change the phase and polarization state of the reflected wave. Can be changed.

In particular, in the fishnet structure of FIG. 10, a plurality of conductive fibers having a substantially rectangular shape (square shape) in a plan view are formed on the front surface, the back surface, or the inner layer of the base cloth 12 to which the conductive cloth 13 is attached to the back surface. It has a structure in which it is connected in a vertical and horizontal mesh pattern by linear conductive fibers.
Further, as shown in FIG. 11B, which is a cross-sectional view taken along the line AA of FIG. 11A, the mushroom structure of FIG. 11 is substantially plan-viewed on the surface of the base cloth 12 to which the conductive cloth 13 is attached to the back surface. A plurality of rectangular (square) conductive fibers are formed, and these are connected to the conductive cloth 13 via the base cloth 12 by the linear conductive fibers at the substantially central positions in the plan view. I'm doing it.

This is because these shapes have an EBG (Electromagnetic Band Gap), and the phase of the electromagnetic wave incident on the resonance structure 11 is inverted by 180 ° near the resonance frequency. Since the frequency strongly depends on the dielectric constant and magnetic permeability of the base cloth 12, the shape and conductivity of the conductive fibers, the physical quantity can be estimated by measuring or calculating the phase change due to these in advance.

[Fourth Embodiment]
Next, the wearable sensor 10 according to the fourth embodiment of the present invention will be described with reference to FIGS. 12 to 14. FIG. 12 is an explanatory diagram showing a configuration of a wearable sensor (notched split ring structure) according to the fourth embodiment. FIG. 13 is an explanatory diagram showing a configuration of a wearable sensor (notched cross dipole structure) according to the fourth embodiment. FIG. 14 is an explanatory diagram showing a configuration of a wearable sensor (notched open ring structure) according to the fourth embodiment.

In the first to third embodiments described above, the resonance structure 11 is formed by patterning by sewing conductive fibers to the base fabric 12. However, in these cases, since the circuit structure becomes three-dimensional, unexpected reactance components and capacitance components are likely to occur, which causes a problem that the deviation from the design becomes large.
In order to solve this problem, the resonance structure 11 may be formed by cutting out the conductive base cloth 14.

In particular, in the notched split ring structure of FIG. 12, a plurality of resonance structures 11 are formed by cutting out a part of the conductive base cloth 14 into a split ring structure, more specifically, a substantially C-shape in a plan view. It has a structure.
Further, the notched cross dipole structure of FIG. 13 is a structure in which a plurality of resonance structures 11 are formed by cutting out a part of the conductive base cloth 14 into a cross dipole structure, more specifically, a substantially cross shape in a plan view. Is doing.

Further, the notched open ring structure of FIG. 14 is a structure in which a plurality of resonance structures 11 are formed by cutting out a part of the conductive base cloth 14 into an open ring structure, more specifically, a substantially frame shape in a plan view. Is doing. At this time, in order to hold the conductive base cloth 14 in the inner portion of the frame shape, the base cloth 12 is attached to the back surface of the conductive base cloth 14.
In addition, a cutout dipole structure similar to that shown in FIG. 8 or a cutout fishnet structure similar to that shown in FIG. 10 may be applied.

By forming the resonance structure 11 by cutting out the conductive base cloth 14 in this way, it is possible to omit the step of easily forming a three-dimensional structure such as sewing of conductive fibers, and it is easy to obtain the characteristics as designed. The excellent effect is exhibited.

[Fifth Embodiment]
Next, the wearable sensor 10 according to the fifth embodiment of the present invention will be described with reference to FIG. FIG. 15 is an explanatory diagram showing a configuration of a wearable sensor (composite type) according to a fifth embodiment.

Regarding the resonance structure 11 described in the first to fourth embodiments described above, it is not necessary to limit all the resonance structures 11 arranged in one wearable sensor 10 to the same shape, and as shown in FIG. 15, it is arbitrary. The composite wearable sensor 10 may be formed by arranging the resonance structures 11 in combination. Further, the resonance structures 11 having the same shape and having different shape parameters such as size may be combined and arranged.

As a result, the resonance structures 11 having different characteristics can be integrated in the same plane, and there is an excellent effect that one wearable sensor 10 can realize a plurality of functions such as correspondence to the incident direction of electromagnetic waves and measurement of different physical quantities. can get.

[Extension of Embodiment]
Although the present invention has been described above with reference to the embodiments, the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the structure and details of the present invention within the scope of the present invention. In addition, each embodiment can be implemented in any combination within a consistent range.

1 ... sensor system, 10 ... wearable sensor, 11 ... resonant structure, 12 ... base cloth, 13 ... conductive cloth, 14 ... conductive base cloth, 21 ... high frequency oscillator, 22 ... transmit antenna, 23 ... receive antenna, 24 ... Measuring device, 25 ... transmission / reception antenna, 26 ... isolator.

Claims (4)

A wearable sensor used in a sensor system that measures a specific physical quantity based on the comparison result of transmitted and received electromagnetic waves.
It is formed of a conductive medium to the non-conductive base fabric, together with changing the electromagnetic waves incident by resonating the input and shines electromagnetic waves, to vary the degree of change with respect to the electromagnetic wave by deformation in accordance with the physical quantity A wearable sensor characterized by having a resonance structure. In the wearable sensor according to claim 1,
Among the resonance structures, the resonance structure formed by the conductive medium is a wearable sensor having a split ring structure, a dipole structure, a cross dipole structure, a fishnet structure, or a mushroom structure. In the wearable sensor according to claim 1,
Among the resonance structures, the resonance structure formed by the conductive medium is a wearable sensor characterized in that it is formed by applying the conductive medium to the base cloth. A sensor system that transmits and receives electromagnetic waves to the wearable sensor according to any one of claims 1 to 3 , and measures a specific physical quantity based on a comparison result between the transmitted electromagnetic waves and the received electromagnetic waves.

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