JP2007093549A - Sensor, and device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensor capable of preventing a solution from intruding into a space in a reverse side of a piezoelectric plate, capable of bringing quickly pressure of the space into pressure in an outside of the sensor, capable of uniformizing characteristics between the sensors, and easy to be attached to a measuring device. <P>SOLUTION: One electrode out of the electrodes provided on both faces of the piezoelectric plate is fixed in one end side of a substrate to be covered via a space, and a ventilation port is provided on an end face of the other end side of the substrate to be penetrated from the ventilation port to the space. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sensor including an oscillator that oscillates a signal having a predetermined frequency when immersed in a liquid, and an apparatus for measuring the amount of a substance in the liquid using the sensor.

Patent Document 1 proposes a sensor configured by providing an oscillator on a substrate.
In this document, the gas is held in the space formed by the back surface of the piezoelectric plate and the plastic covering material, and the back side The electrode in the space is prevented from coming into contact with the solution and short-circuited with the electrode on the front surface, and furthermore, the opening in the covering material is made to communicate with the space facing the electrode on the back surface, so that the atmospheric pressure in the space is kept constant. It has been proposed to hold and stabilize the oscillation frequency of the resonator in a relatively short time.

  On the other hand, Patent Document 2 discloses a vibrator in which a needle is fixed with epoxy resin in a space in order to keep the space formed by the back surface of the piezoelectric plate and the polyacrylic coating material at atmospheric pressure. .

However, in the sensor proposed in Patent Document 1, when the sensor is immersed in a solution for a long time or left immersed in a solution containing a surfactant, the opening is also immersed in the solution. Therefore, there was a problem that the solution entered from the opening provided in the covering material, resulting in a measurement error and a short circuit.
In addition, the sensor configuration proposed in Patent Document 2 has a problem that the manufacturing process is complicated because a plurality of members are used, and the characteristics between the manufactured sensors vary.

International Publication WO02 / 061396 Pamphlet JP-A-8-338798

  Therefore, the present invention has an object to quickly change the atmospheric pressure outside the sensor without causing the solution to enter the space behind the piezoelectric plate, and to make the characteristics between the sensors uniform. To do. It is another object of the present invention to provide a sensor that can be easily attached to a measuring apparatus. Moreover, it aims at providing the apparatus which uses this.

As a result of intensive studies, the present inventors have found a solution as described below based on the knowledge that the above problem can be solved by providing a through hole in the substrate.
That is, the sensor according to the present invention is fixed to one end of the substrate so that one of the electrodes provided on both sides of the piezoelectric plate is covered with a space. A vent is provided in an end face on the other end side of the substrate, and the substrate is penetrated from the vent to the space.
According to a second aspect of the present invention, in the sensor according to the first aspect, a concave portion is provided on an end surface of the substrate, and the vent is provided in the concave portion.
According to a third aspect of the present invention, in the sensor according to the first or second aspect, the substrate is made of an inorganic material.
Moreover, the measuring apparatus of this invention is provided with the attaching part which can mount | wear with the said ventilation hole of the sensor in any one of Claims 1 thru | or 3 up.

According to the present invention, a structure that can discharge the gas on the back surface of the piezoelectric plate from the end surface of the substrate opposite to the piezoelectric plate is obtained by a simple structure, so that the characteristics between the sensors are uniform. be able to.
In addition, when a concave portion is provided on the end surface of the substrate and a vent is provided in the concave portion so as to communicate with the space, it can also be used as a positioning for inserting the sensor into a socket or the like of the measuring device. it can.
Further, when the substrate is made of an inorganic material, it can be used for both an aqueous solution and a solution using an organic solvent.
In addition, since the measuring device of the present invention can be mounted so that the vent of the sensor is on the upper side, the gas in the space formed on the back side of the piezoelectric plate can move quickly with changes in temperature.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the present embodiment.
As shown in FIG. 1, the sensor of the present embodiment is provided with an oscillator 2 on one end side of a substrate 1. The oscillator 2 includes a piezoelectric plate 3 formed in a circular shape, and electrodes 4 and 5 that are also formed in a circular shape at substantially central portions of both surfaces thereof. Lead electrodes 6 and 7 are provided from the electrodes 4 and 5 toward the outer peripheral direction of the piezoelectric plate 3 so as to be opposite to each other. Connection terminals 8 and 9 formed in an arc shape are formed. As shown in the figure, the lead wire 6 on the front side of the piezoelectric plate 3 goes around to the back side, and the connection terminals 8 are arranged on the back side of the piezoelectric plate 3.

The electrode 5 on the back side of the piezoelectric plate 3 is fixed to the substrate 1 with a predetermined space 10. Specifically, in FIG. 3, as shown in the BB cross section of FIG. 1, a circular recess 11 is provided at the end on one end side of the substrate 1 so that the piezoelectric plate 3 can be fitted. The inner peripheral surface of the recess 11 is formed in a step shape so that the electrode 5 on the back side of the piezoelectric plate 3 does not contact the substrate 1.
The connection terminals 13 and 14 are also provided on the flat portion 12 of the staircase on the inner peripheral surface of the recess 11, and the connection terminals 8 and 9 provided on the piezoelectric plate 3 are bonded by the conductive adhesive 15. . The conductive adhesive 15 is not limited as long as it has the required conductivity and adhesiveness, and for example, a silver-dispersed epoxy resin or the like can be used.
As shown in FIG. 1, the connection terminals 13 and 14 of the substrate 1 extend to the other end side of the substrate 1 through the wiring 16 provided inside the substrate 1. It will be connected to an external power source.

In the present invention, the space 10 on the back side of the piezoelectric plate 3 communicates with a vent hole 20 provided on the end surface opposite to the piezoelectric plate 3 as shown in the AA cross section of FIG.
As a method of forming this air passage, there is a cutting method or the like, but there is no particular limitation, but it is also possible to form a groove serving as an air passage in one or a plurality of plate members and bond them together. it can.
The inner diameter of the air passage is not particularly limited, but can be in the range of 0.3 mm to 3.0 mm. When the material constituting the substrate 1 is ceramic, it is preferable to set the range of 1 mm to 2 mm in order to reduce the rate of occurrence of cracks during sintering and to obtain good followability to pressure changes. . Moreover, although there is no restriction | limiting in particular about the cross-sectional shape of a ventilation path, For example, it can be set as a rectangular shape, circular shape, etc.
Moreover, there is no restriction | limiting in particular also about the number of ventilation paths, A plurality of ventilation openings 20 may be provided to form a plurality of ventilation paths.

As shown in FIG. 1, the sensor 30 described above has a recess 21 formed on the end surface opposite to the piezoelectric plate 3, and a vent hole 20 is provided in the recess 21 to communicate with the space 10. preferable. This is because the position where the sensor 30 is attached can be confirmed by the recess 21. In addition, after attachment, air permeability can be ensured from a slight space between the recess 21 and the attachment portion.
The shape of the recess is not particularly limited, but is preferably a notch groove as shown. Moreover, when it is set as a notch groove, there is no restriction | limiting in particular about the cross-sectional shape, For example, a cross section can be made into square shape, a triangular shape, etc.

  The substrate 1 described above is formed as a shape extending from the side on which the piezoelectric plate 3 is provided toward the other end, that is, as an elongated piece. If a specific example is given, it can form in the range of length 10-80mm, width 3-50mm, and thickness 1-15mm.

The substrate 1 is preferably made of a material having a dimensional change rate of 10% or less.
When a material with a dimensional change rate exceeding 10% is used, peeling occurs on the adhesive surface of the conductive paste and the oscillation stops, stress is applied to the piezoelectric plate 3 due to the dimensional difference, or the measured value is not stable or stable. It takes a long time to complete, or the amount of response to disturbances such as changes in the environment is different, resulting in a difference in noise level. Even for the same measurement change, the detection limit difference due to the difference in S / N ratio This is because there is a problem of becoming affected.

  The material constituting the substrate 1 is preferably an inorganic material. Moreover, even if it is a single member, the coating of the inorganic material may be given so that a solution may not osmose | permeate with respect to a single member. Specifically, inorganic materials such as glass, ceramic, metal, carbon, and quartz are preferable, and among these, ceramic is preferable because good dimensional accuracy can be obtained by molding. preferable. By configuring the substrate 1 with an inorganic material, it is unlikely that the shape is unstable or the dimensions will vary among individual sensors when the sensor is assembled or used for measurement. This is because the reproducibility of the measured value is good. Conventionally, it was said that the oscillation frequency could not be stabilized at an early stage without using a flexible material such as silicone resin. It is because I discovered.

In the present specification, the dimensional change rate is defined as follows.
A test piece made of the material constituting the substrate 1 (longitudinal side 1 cm, lateral side 1 cm, thickness 5 mm) is allowed to stand for 24 hours in a thermostatic chamber set at a temperature of 25 ± 0.1 ° C. and normal pressure. The length measuring device measures the length of the vertical side and the horizontal side, and these are set as a and b, respectively.
Then, under normal pressure, the test piece is immersed in the target solution and taken out after 3 hours, and the lengths of the vertical and horizontal sides are measured in the same manner as described above. Let b ′. In the immersion in the solution, the temperature of the solution is set to 25 ° C. ± 0.1 ° C. under normal temperature and normal pressure.
And the dimensional change rate of the said test piece is computed by a following formula. The dimensional change rate was obtained for a total of five test pieces, and the average value was defined as the dimensional change rate referred to in this specification.
Dimensional change rate (%) = | ((b′−b) + (a′−a)) / 2 | / (a + b) × 100

  The target solution is a solution in which the sensor of the present invention is immersed, and is different for each measurement. Examples of the solution used for the measurement are acetylene, acetaldehyde, acetonitrile, acetone, aniline, isobutyl alcohol, isopropyl alcohol, diethyl ether, ethanolamine, ethyl alcohol, ethylbenzene, ethylene glycol, ethyl chloride, methyl chloride, Xylene, glycerin, chlorotoluene, chloronaphthalene, chloroform, diethyl ether, diethylene glycol, carbon tetrachloride, dioxane, cyclohexane, dichlorobenzene, dibutyl ether, dimethyl sulfoxide, dimethylformamide, tetrachloroethane, tetrahydrofuran, triethanolamine, trichloroethylene, toluene , Perchlorethylene, pyridine, phenol, butyl alcohol, butyl cellosolve, Pills alcohol, difluorobenzene, hexa aldehydes, hexane, there are benzyl alcohol, benzaldehyde, benzene, any or a mixture of at least two of these formaldehyde and methyl alcohol.

Next, the measuring apparatus of the present invention provided with the sensor 30 will be described.
As shown in FIG. 4, the measuring apparatus of the present invention includes an attachment portion 22 that can be attached with the vent 20 of the sensor 30 on the upper side, and an AC voltage is applied to the electrodes 4 and 5 of the piezoelectric plate 3. As long as it is possible to measure the change of the vibration frequency and the like, there is no particular limitation, and it is possible to simply measure the electrical characteristics such as the frequency of the oscillation circuit and the sensor 30, or a network analyzer. Of course, those using an impedance analyzer are also included.

The measurement is performed after the sensor 30 is inserted into the mounting portion 22. At this time, as described above, the groove 21 is formed on the end surface opposite to the piezoelectric plate 3, and positioning when inserting is easy. become.
Further, by inserting the sensor 30 into the mounting portion 22, the air passage of the sensor 30 is arranged in the vertical direction. Thereby, the gas in the space 10 on the back side of the piezoelectric plate 3 can quickly move in the vertical direction due to a temperature change. In addition, gas enters and exits between the sensor 30 and the attachment portion 22 through a gap between the groove 21 and the attachment portion 22.

The above-mentioned piezoelectric plate 3 can also use a well-known thing, for example, can use barium titanate, PZT (trademark), etc. besides quartz. Moreover, there is no restriction | limiting in particular also about the shape, In addition to the disk shape demonstrated above, things, such as a rectangular shape, can also be used.
Similarly, the connection terminals 13 and 14 provided on the substrate 1, the electrodes 4 and 5 and the connection terminals 8 and 9 provided on the piezoelectric plate 3 are also publicly known, and a metal material such as gold is vapor deposited. Provided.

  The present invention can be used for measurement using interaction between biological substances such as DNA and protein, antigen-antibody reaction, and the like.

The top view of the sensor of one embodiment of the present invention AA sectional view BB sectional view Explanatory drawing of the attaching part of the measuring apparatus of one embodiment of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Oscillator 3 Piezoelectric plate 4 Electrode 5 Electrode 6 Lead wire 7 Lead wire 8 Connection terminal 9 Connection terminal 10 Space 11 Recess 12 Flat portion 13 Connection terminal 14 Connection terminal 15 Conductive adhesive 16 Wiring 17 Sealing agent 20 Vent 21 recessed portion 22 mounting portion 30 sensor

Claims (4)

  One end of the substrate is fixed so that one of the electrodes provided on both sides of the piezoelectric plate is covered with a space, and a vent is provided on the end surface on the other end of the substrate, A sensor that is penetrated from the vent to the space.   The sensor according to claim 1, wherein a concave portion is provided on an end surface of the substrate, and the vent hole is provided in the concave portion.   The sensor according to claim 1, wherein the substrate is made of an inorganic material. A measuring apparatus comprising: a mounting portion that can be mounted with the vent of the sensor according to claim 1 facing upward.

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