JPH0545339A - Elastic wave element and measuring apparatus of physical property of solution using the element - Google Patents

Abstract

PURPOSE:To obtain an apparatus for measuring physical properties of a solution with using elastic waves to which a solution can be easily injected or removed. CONSTITUTION:A hole of a predetermined shape is formed in a supporting plate 142. When a rear face of a piezoelectric substrate 144 is bonded to the hole, a measuring pond 140 is obtained at the face opposite to where a comb-like electrode 146 is provided. When a solution to-be-measured is injected to or discharged from the measuring pond, the solution is never adhered to the comb- like electrode.

Description

Detailed Description of the Invention

[0001]

This invention relates to solution physical properties such as viscosity,
The present invention relates to an elastic wave element for measuring using an elastic wave element and a solution physical property measuring apparatus using the elastic wave element.

[0002]

2. Description of the Related Art A conventional acoustic wave device and a solution property measuring apparatus will be described.

FIG. 5 is a perspective view of a conventional acoustic wave device for measuring the physical properties of a solution.

The element is a comb-shaped electrode 2 for signal input (hereinafter referred to as "IDT2") on one plane of the piezoelectric substrate 1.
And a comb-shaped electrode 3 for signal output (hereinafter referred to as “IDT3”). Further, on the same surface as the surface on which the IDTs 2 and 3 are provided, the IDTs 2 and I
The measurement pond 4 was provided between the DT 3 and the DT 3. The measuring pond 4 was formed by adhering a "frame" having a predetermined shape on the piezoelectric substrate 1.

When performing measurement with an apparatus using this conventional element, first, the solution to be measured is put into the measuring pond 4.

In this state, when a signal having a predetermined frequency for measurement is input to the IDT 2, a surface wave (hereinafter,
It is called "SH-SAW". Shear Horizontal-Surface A
coustic Wave) is excited.

The SH-SAW is a piezoelectric substrate 1
Of the IDT3 and is detected by the IDT3. At this time,
The phase velocity of the SH-SAW changes under the influence of the physical properties of the solution in the measurement pond 4, for example, the viscosity.
Therefore, the physical properties are measured by detecting the change in the phase velocity.

[0008]

However, in the above-mentioned prior art, since the measuring pond 4 is very small, it was difficult to completely remove the solution when removing the measuring solution.
In addition, when the solution was injected or removed, the solution sometimes adhered to the IDTs 2 and 3 and the measurement could not be performed.

Further, it has been difficult to bond the measuring pond 4 to the surface of the piezoelectric substrate 1 so as not to affect the propagation of SH-SAW.

An object of the present invention is to inject a solution to be measured,
An object of the present invention is to provide an elastic wave element that can be easily removed and a solution physical property measuring apparatus using the same.

[0011]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object, and comprises a piezoelectric substrate, an input comb-shaped electrode provided on one surface of the piezoelectric substrate, and an input comb-shaped electrode on the surface. ,
It has an output comb-shaped electrode provided in pair with the input comb-shaped electrode, and a measurement pond for containing a solution to be measured, which is provided on a surface opposite to the surface. An elastic wave element characterized by the above is provided.

Further, there is provided a solution physical property measuring apparatus comprising the elastic wave element and transmitting means capable of transmitting an electric signal having a wave number for generating an elastic wave in the piezoelectric substrate.

[0013]

[Function] The solution to be measured is injected into the measuring pond. In this case, since the measuring pond is provided on the surface opposite to the comb-shaped electrode, there is no possibility that the solution will adhere to the electrode.

In this state, the transmitting means is operated to generate an elastic wave in the elastic wave element. Unlike surface waves, elastic waves propagate not in the vicinity of the surface of the piezoelectric substrate but in the bulk region, and thus are affected by the physical properties of the solution in the measurement pond provided on the surface opposite to the electrode. In other words,
Even if the measurement pond is on the back side of the surface on which the comb-shaped electrode is provided, the physical properties of the solution can be measured.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG.

FIG. 1 shows a schematic view of the solution physical property measuring apparatus of this embodiment.

The solution physical property measuring apparatus is intended for measuring the viscosity of a liquid, and is mainly composed of an oscillator 10, a switch 12, an elastic wave element sensor 14, and a phase difference detecting circuit 16.

The oscillator 10 is for generating an electric signal for generating an elastic wave used for measurement.

There are various elastic waves depending on the thickness of the substrate and the frequency as shown in FIG. 2, but the elastic wave having a frequency at which the X2 direction component is excited relatively large is measured. It is supposed to do.

In the present embodiment, the signal of the oscillator 10 is set to a frequency for generating an elastic wave ((in the present specification, an elastic wave other than a surface wave is referred to as an "elastic wave"). The signal generated by the oscillator 10 is output to the acoustic wave element sensor 14.

The acoustic wave element sensor 14 has a structure having two measuring systems inside. The details of the acoustic wave element sensor 14 will be described later with reference to FIGS. 3 and 4.

The phase difference detection circuit 16 is for detecting the phase difference between the signals output from the two measurement systems of the acoustic wave element sensor 14 described above. This phase difference is caused by the viscosity of the solution, the dielectric constant, the temperature difference between both measuring systems, and the like.

The acoustic wave element sensor 14 will be described in detail.

FIG. 3 shows a circuit configuration of the elastic wave element sensor 14.

The circuit in the elastic wave element sensor 14 includes a measuring system C having a measuring pond 140 for containing a solution to be measured,
And a reference measuring system D without a measuring pond. Then, each measurement system includes an IDT provided on the piezoelectric substrate 144.
It has 146. Although not shown in the figure, both measuring systems have ground conductors on both front and back surfaces of the piezoelectric substrate 144, and short-circuit the both surfaces to remove the influence of the dielectric constant of the solution.

A cross section of the measuring system C having a measuring pond is shown in FIG.

The measurement system C of the present embodiment is characterized in that the measurement pond 140 is arranged on the back side of the piezoelectric substrate 144, that is, the surface on which the IDT 146 is not provided.

The measuring pond 140 is constructed by adhering a piezoelectric substrate 144 to a support plate 142 having holes for forming the measuring pond 140.

The measuring pond 140 must be arranged so as to uniformly affect the elastic waves excited by the IDT 146. Therefore, in this embodiment, when the elastic wave element sensor 14 is viewed from above or below, the measurement pond 140 includes an input IDT 146, an output IDT 146, and an elastic wave propagation path. However, the present invention is not limited to this. Other shapes and sizes may be used as long as they satisfy the above conditions.

However, it is preferable that the measurement pond 140 does not overlap the IDT 146 at all or overlaps so as to include all the IDTs 146 so that the generation or detection of elastic waves is not adversely affected.

The size of the support plate 142 is the size of the piezoelectric substrate 1.
It is large enough to cover 44 sufficiently.
However, the shape and size of the measurement pond 140 and the support plate 142 are not limited to these. Further, the method of joining the measurement pond 140 and the support plate 142 is not particularly limited as long as it is a method that does not affect the elastic waves propagating in the piezoelectric substrate 144.

The operation of measuring the viscosity will be described.

First, the solution to be measured is placed in the measuring pond 140. In this case, the measurement pond 140 is the IDT 14
Since it is provided on the side opposite to 6, there is little possibility that the solution will adhere to the IDT 146.

In this state, by inputting the signal generated by the oscillator 10 to the elastic element sensor 14, the piezoelectric substrate 14
4 produces an elastic wave. Then, the phase difference detection circuit 1
By detecting the phase difference between the two measurement systems at 6, that is, the measurement system C that is affected by temperature and viscosity and the measurement system D that is affected by temperature but not viscosity, It is possible to measure the viscosity while compensating for temperature.

As described above, in the above embodiment, since the elastic wave is used as the elastic wave for measurement,
The measurement pond 140 could be provided on the surface opposite to the IDT 146. By this, formation of the measuring pond during manufacturing,
That is, the support plate 142 and the piezoelectric substrate 144 are easily bonded to each other. In addition, it became easy to inject and remove the solution during the measurement. Furthermore, the risk of the solution adhering to the IDT 146 is reduced. Particularly, in the above embodiment, since the support plate 142 is made larger than the piezoelectric substrate 144,
Adhesion to the IDT 146 can be prevented almost completely.

[0036]

As described above, according to the present invention, it becomes easy to form a pond for containing a solution to be measured in the manufacturing process. Also, when pouring and removing the solution into the pond,
The solution is less likely to adhere to the IDT. Further, the removal of the solution after the measurement becomes very easy.

[Brief description of drawings]

FIG. 1 is a perspective view showing an outline of an embodiment of the present invention.

FIG. 2 is a graph showing the presence of elastic waves.

FIG. 3 is an explanatory diagram showing a circuit configuration of an acoustic wave device.

FIG. 4 is an explanatory diagram of an acoustic wave element sensor having a measurement pond.

FIG. 5 is a perspective view showing a conventional technique.

[Explanation of symbols]

1: Piezoelectric substrate, 2: Comb type electrode (IDT), 3: Comb type electrode (IDT,), 4: Measuring pond, 10: Transmitter, 1
2: switch, 14: elastic wave element sensor, 16: phase difference detection circuit, 140: measurement pond, 142: support plate, 14
4: piezoelectric substrate, 146: IDT, C: measurement system, D: measurement system.

Claims (2)

[Claims] 1. An acoustic wave device for measuring the physical properties of a solution, comprising: a piezoelectric substrate; a comb-shaped electrode for input provided on one surface of the piezoelectric substrate; and the above-mentioned input on the surface. A comb electrode for output, which is provided in a pair with the comb electrode for use, and a measuring pond, which is provided on a surface opposite to the surface, for containing a solution to be measured. An acoustic wave device characterized by the above. 2. An apparatus for measuring physical properties of a solution, comprising: the elastic wave device according to claim 1; and a transmitting means capable of transmitting an electric signal having a frequency for generating an elastic wave in the piezoelectric substrate.