JP2019100837A - Sensing device - Google Patents

Abstract

To provide a sensing device using a split ring resonator capable of increasing detectable bandwidth.SOLUTION: The sensing device includes a split ring resonator 101, a transmission line 103, and a sensing area 104. The sensing device is constituted of the split ring resonator 101 and the transmission line 103. An inductance variable part 105 is disposed on a wiring pattern of the split ring resonator 101. The inductance variable part 105 is made of a material having a relative permeability of 1 or more. The inductance variable part 105 is configured so that the distance from the wiring pattern is changeable.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a sensing device for sensing dielectric characteristics of a dielectric.

  In recent years, there has been proposed a technique for sensing the dielectric characteristics of a dielectric with high sensitivity by a structure in which a split ring resonator often used in metamaterials and a transmission line are coupled. The split ring resonator is composed of a ring-shaped metal pattern having a gap in part. In the split ring resonator, a ring-shaped metal pattern (hereinafter sometimes referred to as "ring portion") functions as an inductive component L, and a metal pattern facing each other across a gap functions as a capacitive component C. The split ring resonator has an LC resonant mode in which a circular current is excited in the ring portion and an electric field is concentrated in the gap. In metamaterial devices, generally, the resonance mode described above is used to realize the metamaterial-specific phenomenon.

  In the sensing application of metamaterials, by forming the split ring resonator finely, the electric field can be concentrated in a very small area compared to the wavelength, so the dielectric characteristics of the dielectric are sensed in the gap of the split ring resonator Technology is being studied. For example, Non-Patent Document 1 discloses a configuration shown in FIG. In this structure, the transmission line 503 is disposed on the opposite side of the gap 502 of the split ring resonator 501, and the transmission line 503 is electromagnetically coupled to the split ring resonator 501. Further, a channel 521 is provided in the vicinity of the gap 502 of the split ring resonator 501, a liquid to be sensed is introduced into the channel 521, and this is an area for sensing the dielectric characteristics of the introduced liquid.

  In this sensing element, a signal matching the LC resonant frequency of the split ring resonator 501 is made to flow through the transmission line 503, the electric field is concentrated in the gap 502 of the split ring resonator 501, and the dielectric characteristics of the liquid are sensed with high sensitivity. There is. The split ring resonator 501 and the transmission line 503 are formed on the substrate 511. In addition, a microstrip line is configured by the transmission line 503 and the metal layer 506 formed on the back surface of the substrate 511 (except for the region with respect to the split ring resonator 501 and the vicinity thereof).

W. Withayachumnankul et al., "Metamaterial-based microfluidic sensor for dielectric characterization", Sensors and Actuators A: Physical, vol. 189, pp. 233-237, 2013.

  However, in the above-described prior art, the sensitivity is improved only at the resonance frequency of the resonator where the electric field is concentrated locally, so that there is a problem that broadband spectral information can not be detected with high sensitivity.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to widen the detectable band in a sensing element using a split ring resonator.

  A sensing device according to the present invention includes a split ring resonator formed of a metal pattern having a wiring pattern formed in a polygon in a plan view and having a gap in part, and a split ring resonator formed on a substrate A wiring pattern electromagnetically coupled to the sensor, a sensing region for detecting a dielectric characteristic, and an inductance variable portion formed of a material having a relative permeability of 1 or more disposed on the wiring pattern; The distance between and the variable inductance portion is made changeable.

  The sensing device further includes a variable mechanism that changes the distance between the wiring pattern and the inductance variable portion.

  In the sensing device, the variable mechanism may change the distance between the wiring pattern and the inductance variable portion by moving the inductance variable portion in the normal direction of the plane of the substrate. In this case, the variable mechanism may change the distance between the wiring pattern and the inductance variable portion on each of both sides of the substrate.

  In the above sensing device, the variable mechanism may change the distance between the wiring pattern and the inductance variable portion by moving the inductance variable portion in a direction parallel to the plane of the substrate.

  As described above, according to the present invention, since the variable inductance portion made of a material having a relative permeability of 1 or more is provided, which allows the distance from the wiring pattern of the split ring resonator to be changed. The excellent effect is obtained that the detectable band in the sensing device using the ring resonator can be broadened.

FIG. 1 is a plan view showing the configuration of a sensing device according to an embodiment of the present invention. FIG. 2A is a cross-sectional view showing a configuration of a sensing device according to an embodiment of the present invention. FIG. 2B is a cross-sectional view showing the configuration of the sensing device in the embodiment of the present invention. FIG. 2C is a cross-sectional view showing the configuration of the sensing device in the embodiment of the present invention. FIG. 3 is a characteristic diagram showing the result of analyzing the dependence of the resonance peak intensity in the split ring resonator 101 and the transmission line 103 on the distance between the inductance variable portion 105 and the wiring pattern by electromagnetic field simulation. FIG. 4 is an explanatory diagram for explaining a method of changing the resonance frequency of the split ring resonator 101. As shown in FIG. FIG. 5A is a characteristic diagram showing a result of sensing a dielectric whose relative dielectric constant is ε _{1 and} a dielectric whose relative dielectric constant is ε ₂ (ε ₁ <ε ₂ ) with variable capacitance component. FIG. 5B is a characteristic diagram showing a result in the case of sensing a dielectric whose relative dielectric constant is ε _{1 and} a dielectric whose relative dielectric constant is ε ₂ (ε ₁ <ε ₂ ) with variable inductance component L. FIG. 6A is a configuration diagram showing a configuration of a variable mechanism that changes the distance between the wiring pattern and the inductance variable portion. FIG. 6B is a configuration diagram showing a configuration of a variable mechanism that changes the distance between the wiring pattern and the inductance variable portion. FIG. 6C is a configuration diagram showing a configuration of a variable mechanism that changes the distance between the wiring pattern and the inductance variable portion. FIG. 6D is a configuration diagram showing a configuration of a variable mechanism that changes the distance between the wiring pattern and the inductance variable portion. FIG. 7A is a plan view showing another configuration of the sensing element constituting the sensing device in the embodiment of the present invention. FIG. 7B is a plan view showing another configuration of the sensing element constituting the sensing device in the embodiment of the present invention. FIG. 8 is a plan view showing a partial configuration of a conventional sensing element using the split ring resonator 501. As shown in FIG.

  Hereinafter, a sensing device according to an embodiment of the present invention will be described with reference to FIG. The sensing device includes a split ring resonator 101, a transmission line 103, and a sensing area 104. The split ring resonator 101 and the transmission line 103 constitute a sensing element.

  The split ring resonator 101 is formed on a substrate 111. The substrate 111 may be made of a dielectric (insulator). Further, the split ring resonator 101 is formed of a metal pattern having a gap 102 in part. The split ring resonator 101 has a wiring pattern (ring portion) formed in a polygon in plan view. The gap 102 is formed on one of a plurality of sides of the polygon formed by the wiring pattern. The transmission line 103 is electromagnetically coupled to the split ring resonator 101. The sensing area 104 is an area for detecting dielectric characteristics.

  Further, in the sensing device in the embodiment, the inductance variable unit 105 is disposed on the wiring pattern of the split ring resonator 101. The inductance variable portion 105 is made of a material having a relative permeability of 1 or more. Further, the inductance variable portion 105 can change the distance to the wiring pattern.

  In addition, as shown in FIGS. 2A, 2B, and 2C, the sensing device according to the embodiment includes the transmission line 103 and a metal layer 106 for forming a microstrip line on the back surface of the substrate 111. FIG. 2A shows a cross section taken along line aa 'of FIG. Further, FIG. 2B shows a cross section taken along line bb 'of FIG. Further, FIG. 2C shows a cross section along the line cc 'in FIG.

  Further, in this example, the metal layer 106 is not formed on the region where the split ring resonator 101 is disposed and the back surface in the vicinity thereof in plan view. With this configuration, in the sensing region 104, even on the back surface side of the substrate 111, sensing of the target liquid becomes possible.

  In this sensing device, by providing a flow path passing through the upper part of the gap 102 of the sensing area 104, it is possible to send the liquid to be sensed to the flow path.

  Next, the transmission line transmission characteristics of the sensing element constituting the sensing device in the above-described embodiment will be described using FIG. 3 as a result of simulation. First, the dimensions of each part shown in FIG. 1 were A = 1.8 mm, B = 2.5 mm, m = 3 mm, s = 0.08 mm, w = 0.08 mm, g = 0.8 mm. The dimensions of the inductance variable portion 105 were Mx = 0.8 mm, My = 0.7 mm, and Mz = 1.5 mm. Moreover, the inductance variable part 105 was comprised from the magnetic body whose relative magnetic permeability is 200 and a relative dielectric constant is one.

  In FIG. 3, the numbers in the graph indicate the distance between the inductance variable unit 105 and the wiring pattern. As shown in FIG. 3, the inductance variable unit 105 changes the resonant frequency of the split ring resonator 101 depending on the distance from the wiring pattern.

Next, a method of changing the resonance frequency of the split ring resonator 101 will be described with reference to FIG. The resonant frequency _fr of the split ring resonator 101 is determined by the LC resonant frequency determined by the capacitance component C and the inductance component L of the split ring resonator 101. Among them, as shown in FIG. 4A, a method of connecting a variable capacitance device (not shown) to the gap 102 to make the capacitance component C variable is considered as a method of changing the resonance frequency. Further, as shown in FIG. 4B, a method of making the inductance component L of the portion of the wiring pattern of the split ring resonator 101 variable is considered as a method of changing the resonance frequency.

Here, the sensing region 104 is a gap 102 in which an electric field is concentrated at the time of resonance. This means that the dielectric characteristic of the sensing target disposed in the sensing region 104 is observed as a change in the gap 102 capacity of the resonator. When controlling the capacitive component, let C _i be the capacitance determined by the dielectric characteristics and dimensions of the sensing object and the dimension (spacing) of the gap 102, and C _v be the capacitance of the variable capacitance device. The resonant frequency f _r is represented by the following equation (1).

This means that when the capacitance C _v of the variable capacitance device is large compared to C _i , the value of C _v becomes dominant to determine the resonant frequency f _r and not depend on the value of C _i . As shown in FIG. 5A, in the case of sensing a dielectric having a relative permittivity of ε ₁ and a dielectric having a relative permittivity of ε ₂ (ε ₁ <ε ₂ ), in the region where C _v is large, both f _r Difference (correlation) becomes smaller and the sensitivity is degraded. Thus, the C _v increases, the correlation between C _i which is determined by the dielectric properties of the sensing target resonance frequency f _r is decreased, a method of changing the resonant frequency f _r by a variable capacitance C _v, the sensing Degrade the sensitivity of the

On the other hand, when the resonance frequency _fr is changed by changing the inductance component L, the resonance frequency fr of the split ring resonator 101 is _expressed by the following equation (2).

In this case, when C _i changes according to the dielectric characteristic of the sensing target, the resonance frequency f _r also changes regardless of the value of the inductance component L. As shown in Figure 5B, the dielectric having a relative dielectric constant of epsilon _1, and if the relative dielectric constant sensing epsilon ₂ of the dielectric, at L is large area, the difference of both f _r (correlation) is not changed . That is, the method of changing the resonance frequency f _r by the change of the inductance component L does not deteriorate the sensitivity of sensing. As described above, when high sensitivity sensing is performed over a wide band by changing (sweeping) the resonant frequency of the split ring resonator 101, a method of changing the frequency (sweeping) is realized by changing the inductance component L I understand that is good.

  Next, the change of the inductance component will be described. In order to control the inductance component, a switch or the like may be introduced to the ring portion (wiring pattern) of the split ring resonator 101 to switch the path length of the circulating current induced at the time of LC resonance. However, in this method, changes in L become discrete, and the spectral information of sensing also becomes discrete.

  On the other hand, in the embodiment, the inductance component is continuously controlled by changing the distance between the wiring pattern and the inductance variable portion 105. For example, the distance (relative distance) between the wiring pattern and the inductance variable portion 105 may be changed using a variable mechanism.

  For example, the variable mechanism shown in FIG. 6A may be used. The variable mechanism includes a support base 201, a lifting and lowering mechanism 202 using a ball screw, and a table 203 which is lifted and lowered by the lifting and lowering mechanism 202. In addition, a fixing portion 204 for fixing the sensing element is supported on and fixed to the support base 201 at a distance using the elevating mechanism 202. By raising and lowering the table 203 by the raising and lowering mechanism 202, the distance between the wiring pattern of the split ring resonator 101 and the inductance variable portion 105 fixed to the table 203 can be changed continuously.

  Also, the variable mechanism shown in FIG. 6B may be used. The variable mechanism includes a support base 201, a lifting and lowering mechanism 202 using a ball screw, and a table 203 which is lifted and lowered by the lifting and lowering mechanism 202. In addition, the sensing element is fixed to the support 201. By raising and lowering the table 203 by the raising and lowering mechanism 202, the distance between the wiring pattern of the split ring resonator 101 and the inductance variable portion 105 fixed to the table 203 can be changed continuously.

  For example, the variable mechanism shown in FIG. 6C may be used. The variable mechanism includes a support base 201, lifting mechanisms 202a and 202b using ball screws, and tables 203a and 203b which are lifted and lowered by the lifting mechanisms 202a and 202b. A fixing portion 204 for fixing the sensing element is supported on and fixed to the support base 201 at a distance using the elevation mechanism 202a.

  In this variable mechanism, the wiring pattern of the split ring resonator 101 and the inductance variable portion fixed to the table 203a by raising and lowering the table 203a by the raising and lowering mechanism 202a on the support table 201 side (lower side) of the fixed unit 204 The distance to 105a can be changed continuously.

  Further, in this variable mechanism, the distance between the wiring pattern of the split ring resonator 101 and the inductance variable portion 105b fixed to the table 203b can be increased by moving the table 203b up and down by the lift mechanism 202b above the fixed portion 204. It can change continuously. As described above, by changing the distance between the inductance variable portion and the wiring pattern on both the front surface side and the back surface side of the sensing element, the sweep range of the resonance frequency is increased as compared with the case where it is changed with only one.

  Also, a variable mechanism shown in FIG. 6D may be used. The variable mechanism includes a support structure 205, a moving mechanism 206 using a ball screw, and a table 207 moved by the moving mechanism 206. The moving mechanism 206 moves the table 207 in a direction parallel to the plane of the upper surface (lower surface) of the support structure 205. The moving mechanism 206 moves the table 207, for example, in the left-right direction on the paper surface of FIG. 6D. In addition, the sensing element is fixed to the upper surface of the support structure 205.

  In this variable mechanism, by moving the table 207 by the moving mechanism 206, the inductance variable unit 105 moves in parallel with the plane of the substrate 111 of the sensing element. By moving the inductance variable portion 105 in this manner, the distance between the wiring pattern of the split ring resonator 101 and the inductance variable portion 105 fixed to the table 203 may be continuously changed.

  As shown in FIG. 7A, two split ring resonators 301a and 301b having a single gap 302 in common may be provided on the substrate 311. The transmission line 303 is formed to surround the division ring resonator 301 a and the division ring resonator 301 b. A metal layer 306 is formed on the back surface of the substrate 311. The metal layer 306 is not formed in the arrangement region of the split ring resonator 301 a and the split ring resonator 301 b in plan view.

  Further, as shown in FIG. 7B, two split ring resonators 401a and 401b may be provided on the substrate 411, with one transmission line 403 in common. In this case, a gap 402a is formed in the split ring resonator 401a, and a gap 402b is formed in the split ring resonator 401b. In addition, on the back surface of the substrate 411, a metal layer 406 is formed.

  Further, the split ring resonator and the transmission line (delay line) do not have to be formed in the same plane. For example, the split ring resonator may be formed on the front surface of the substrate, and the transmission line may be formed on the back surface of the substrate (the surface opposite to the surface on which the split ring resonator is disposed). With this configuration, it is possible to form a region where the split ring resonator and the transmission line overlap in plan view. In this case, a metal layer for forming a microstrip line may be formed on the transmission line via another substrate. The other substrate may be made of a dielectric (insulator).

  Further, the metal layer may be formed in the arrangement region of the split ring resonator in plan view, and may not be formed in the arrangement region of the split ring resonator in plan view. In addition, the substrate is composed of a multilayer substrate consisting of a plurality of dielectric layers and metal wiring layers, the split ring resonator is formed on any metal wiring layer of the multilayer substrate, and the metal wires constituting the transmission line are You may form in another metal wiring layer different from the metal wiring layer in which the split ring resonator is formed.

  As described above, according to the present invention, since the variable inductance portion made of a material having a relative permeability of 1 or more is provided, which can change the distance to the wiring pattern of the split ring resonator. This makes it possible to widen the detectable band in a sensing device using a split ring resonator.

  The present invention is not limited to the embodiments described above, and many modifications and combinations can be made by those skilled in the art within the technical concept of the present invention. It is clear. For example, in the above description, the wiring structure of the split ring resonator is rectangular in plan view, but the present invention is not limited to this. For example, the wiring structure of the split ring resonator may be triangular, pentagonal or hexagonal in plan view.

  101: split ring resonator, 102: gap, 103: transmission line, 104: sensing region, 105: inductance variable part, 106: metal layer, 111: substrate.

Claims (5)

A split ring resonator formed of a metal pattern having a gap in part and having a wiring pattern formed in a polygon in plan view, formed on a substrate;
A transmission line electromagnetically coupled to the split ring resonator;
A sensing region for detecting dielectric characteristics;
And an inductance variable portion formed of a material having a relative permeability of 1 or more disposed on the wiring pattern,
A distance between the wiring pattern and the variable inductance portion is changeable. In the sensing device according to claim 1,
A sensing device further comprising a variable mechanism that changes the distance between the wiring pattern and the variable inductance portion. In the sensing device according to claim 2,
A sensing device, wherein the variable mechanism changes a distance between the wiring pattern and the inductance variable portion by moving the inductance variable portion in a direction normal to a plane of the substrate. In the sensing device according to claim 3,
The sensing device, wherein the variable mechanism changes a distance between the wiring pattern and the variable inductance portion on each of both sides of the substrate. In the sensing device according to claim 2,
The sensing device, wherein the variable mechanism changes a distance between the wiring pattern and the inductance variable portion by moving the inductance variable portion in a direction parallel to a plane of the substrate.

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