JP2007093553A - Sensor for measuring trace mass amount - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reliable sensor for measuring a trace mass amount, using a quartz oscillator that performs the thickness slide vibration of AT cut, where the vibration section of a crystal raw thin plate and the reinforcement section of the crystal raw thin plate for surrounding the periphery are integrated on the sensor element for measuring a trace mass amount. <P>SOLUTION: The quartz oscillator for performing the thickness slide vibration of AT cut is used, where the vibration section of a crystal raw thin plate and the reinforcement section of the crystal raw thin plate for surrounding the periphery are integrated on the sensor element (QCM sensor element) for measuring trace mass amount. A recess-worked main electrode surface of the sensor element for measuring a trace mass amount at the tip is placed so that it faces the direction of the inside of the vessel of the sensor (QCM sensor) for measuring trace mass amount. The vessel of the QCM sensor is made of glass, crystal, plastic, or ceramic, and the signal input/output end of the QCM sensor element is extended on the outer surface of the QCM sensor vessel. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

          The present invention uses a quartz oscillator that performs AT-cut thickness-slip vibration in which a vibrating portion of a quartz base plate thin plate and a reinforcing portion of a quartz base plate thick plate surrounding it are integrated with a sensor element for measuring a small mass. The present invention relates to a highly reliable sensor for measuring minute mass.

          Conventionally, a sensor element for measuring a minute mass (QCM: Quartz Crystal Microbalance sensor element) using a crystal resonator uses a thickness shear vibration of crystal, and a metal film material formed on the surface of the crystal substrate includes a crystal film. In consideration of adhesion to the substrate, chromium (Cr), nickel chromium (NiCr), titanium (Ti), or the like is used.

          When the entire sensor element for measuring a small mass is immersed in a solution, the metal film on one side of the quartz substrate can be kept in a gas phase without contacting the liquid phase. In order to prevent the solution from entering, the entire peripheral edge portion of the side surface of the sensor element for measuring the minute mass and the surface end portion inside the sensor container for measuring the minute mass of the element must be fixed and sealed with an adhesive or the like. In general, in order to make the influence of vibration of the sensor element for measuring a minute mass as small as possible, a silicon-based insulating adhesive material having a small bonding stress is often used.

          In addition, in the sensor for measuring a minute mass, a minute weight change when the measured reactant adheres to or separates from the surface of the crystal unit is regarded as a frequency change of the crystal unit. In order to adhere to the surface, a sensor for measuring minute mass (hereinafter referred to as a QCM sensor) is basically a disposable method, and in terms of analysis accuracy, the stability of temperature control and the frequency per unit weight Measurement in the high frequency band where the amount of change is large is effective.

JP 2001-153777 A Japanese Patent Laid-Open No. 11-14525

          In addition, the applicant did not find any prior art documents related to the present invention by the time of filing of the present application other than the prior art documents specified by the above prior art document information.

          However, in a conventional sensor for measuring a minute mass (hereinafter referred to as a QCM sensor), when the thickness of the QCM sensor element used is reduced as the quartz substrate becomes higher in frequency, physical sensors such as sealing with an adhesive are used. The sensitivity of the stress is increased, and the amount of the sensor element adhesive may cause the influence of the adhesive part on the vibration region part contributing to the measurement by the QCM sensor element to be not uniform.

          Therefore, in the conventional sensor for measuring a minute mass (QCM sensor), there is a possibility that unnecessary noise is likely to be generated in the measurement data of the QCM sensor even if the frequency is simply increased.

          The present invention has been made under the technical background as described above. Accordingly, the object of the present invention is to provide a crystal element that surrounds a vibrating part of a thin quartz plate and its surroundings in a sensor element for measuring a minute mass. It is an object of the present invention to provide a highly reliable sensor for measuring a small mass using a quartz crystal resonator that performs AT-cut thickness sliding vibration integrally with a reinforcing portion of a thick plate.

          In order to achieve the above object, the present invention provides a micromass measuring sensor using a quartz resonator formed by forming a metal film on the surface of a quartz substrate. The main electrode surface on which the concave portion of the sensor element for measuring a minute mass is formed using an AT-cut thickness-shear vibration crystal in which a reinforcing portion of a quartz base plate surrounding the portion is integrally formed. Is placed so as to face the inside of the sensor container for measuring the minute mass

          Further, the sensor for measuring a minute mass (QCM sensor) is made of glass, crystal, plastic, or ceramic.

          Further, the signal input / output end of the QCM sensor element is extended to the outer surface of the sensor container for measuring the minute mass.

          According to the QCM sensor of the present invention, since the concave main electrode surface of the crystal resonator of the QCM sensor element to be used has a structure facing the inside of the QCM sensor container, the adhesive is placed in the vibration region portion. Moreover, since the same material in which the vibration area of the QCM sensor element is limited to the concave portion can be used in terms of the structure of the QCM sensor element, the QCM sensor can be manufactured extremely efficiently.

          In addition, according to the QCM sensor of the present invention, the thickness and the vibration region portion of the concave vibration region portion of the QCM sensor element can be set by a desired frequency in a state where the material shape of the QCM sensor element is constant. Even if the frequency to be used is different, the QCM sensor container having the same shape can be used.

          In addition, according to the QCM sensor of the present invention, the mechanical strength of the QCM sensor element in the high frequency band is higher than the conventional one, so that the noise component in the measurement data can be significantly reduced.

          Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In addition, the same code | symbol in each figure shall show the same object.

          FIG. 1 is a schematic side view of a QCM sensor 4 mounted with a QCM sensor element 5 for high frequency measurement above and a QCM sensor element 5 for low frequency measurement below as viewed from the side. That is, the QCM sensor element 5 uses a crystal resonator that performs AT-cut thickness-slip vibration in which a vibrating portion 6 of a quartz base plate thin plate and a reinforcing portion 7 of a surrounding quartz plate thick plate are integrally formed. The QCM sensor element 5 is mounted on the QCM sensor 4 so that the concavely processed main electrode surface 8 faces the inside of the QCM sensor container 9. According to the minute mass measuring sensor 4 (QCM sensor) of the present invention having the QCM sensor 4 having such a structure, the concave main electrode surface 8 of the crystal resonator of the QCM sensor element 5 to be used is the QCM sensor. Since the structure is directed toward the inside of the container 9, it is difficult for the adhesive material to enter the vibration region portion, and the structure of the QCM sensor element 5 is reinforced other than the vibration region portion of the QCM sensor element 5. Since the portion is thick, the QCM sensor 4 can be manufactured remarkably efficiently.

          FIG. 2 is a schematic top view of the QCM sensor 4 of the present invention as viewed from the exposed main surface direction of the QCM sensor element 5. As shown in FIG. 2, the QCM sensor element 5 is not limited to a rectangular shape, and may be a circular shape, an elliptical shape, a trapezoidal shape, a polygonal shape, and the like. Needless to say, it is included in the range.

          FIG. 3 is a schematic diagram showing a conventional QCM sensor element 5 as viewed obliquely from above. For the metal film 2 material formed on the surface of the quartz substrate 1, chromium (Cr), nickel chromium (NiCr), titanium (Ti), etc. are used as the base metal film material in consideration of adhesion to the quartz substrate 1. In addition, gold (Au) or the like is often used as the upper metal film material.

          FIG. 4 is a schematic side view of a conventional QCM sensor element 4 mounted with a low frequency measurement QCM sensor element 5 and a lower QCM sensor element 5 mounted with a high frequency measurement element as viewed from the side. The size of the quartz substrate 1 of the QCM sensor element 5 to be used is increased to secure a sufficient seal path by the adhesive, but depending on the amount of the sensor element adhesive, the vibration area of the QCM sensor element 5 There was a possibility that the influence of the was not uniform.

          FIG. 5 is a schematic top view of the conventional QCM sensor 4 as viewed from the exposed main surface direction of the QCM sensor element 5. In the conventional QCM sensor 4, the QCM sensor element 5 has the shape as shown in FIG. 3. Therefore, when a high frequency crystal resonator is attached to the QCM sensor container 9, the strength of the vibration part is insufficient. As a result, unnecessary noise may easily occur in the measurement data of the QCM sensor 4.

FIG. 5 is a schematic side view schematically illustrating a QCM sensor mounted with a QCM sensor element for high frequency measurement above and a QCM sensor element for low frequency measurement below, respectively, according to the present invention. It is the schematic upper surface figure which looked at the QCM sensor of this invention from the main surface direction which the QCM sensor element exposed. It is the schematic diagram which looked at the conventional QCM sensor element from diagonally upward. It is the general | schematic side surface schematic diagram which looked at the QCM sensor 4 which carried the QCM sensor element for high frequency measurement above each of the conventional, and the QCM sensor element for low frequency measurement below. It is the schematic upper surface figure which looked at the conventional QCM sensor from the main surface direction which the QCM sensor element exposed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Quartz substrate 2 Metal film 3 Quartz crystal oscillator 4 Sensor for measuring minute mass (QCM sensor)
5 Sensor element for measuring minute mass (QCM sensor element)
6 Crystal base plate thin plate vibration part 7 Crystal base plate thick plate reinforcing part 8 Concave processed main electrode surface 9 Sensor container for measuring minute mass (QCM sensor element container)
10 Signal input / output terminal

Claims (3)

In a sensor for measuring micromass using a quartz crystal formed by forming a metal film on the surface of a quartz substrate,
Using a quartz crystal resonator that performs AT-cut thickness-slip vibration in which a vibrating portion of a quartz base plate thin plate and a reinforcing portion of a quartz base plate thick plate surrounding the quartz base plate are integrated as a sensor element for measuring a minute mass, A sensor for measuring a minute mass, characterized in that the concavely processed main electrode surface of the measuring sensor element is placed so as to face the inside of the sensor container for measuring a minute mass.           2. The sensor for measuring micro mass according to claim 1, wherein the sensor container for measuring micro mass is made of glass, crystal, plastic, or ceramic.           2. The sensor for measuring micro mass according to claim 1, wherein a signal input / output end of the sensor element for measuring micro mass extends to an outer surface of the sensor container for measuring micro mass.

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