Measuring and testing – Gas content of a liquid or a solid – By vibration
Reexamination Certificate
1999-08-10
2002-05-21
Williams, Hezron (Department: 2856)
Measuring and testing
Gas content of a liquid or a solid
By vibration
C073S024060, C073S031050, C073S03200R, C073S054410, C073S061750, C073S061790, C073S064530, C073S504120, C073S504160
Reexamination Certificate
active
06389877
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a double-headed mass sensor for determining a minute mass of a nanogram (10
−9
g) order, for example, a mass sensor for sensing microorganisms such as bacteria, viruses, and protozoa or the like (immune sensor), and a mass sensor for sensing moisture, toxic substances, or specific chemical substances such as taste components (moisture meter, gas sensor, and taste sensor), and a method for sensing a mass.
In the present invention, two diaphragms used look like and function as “two heads”, the mass sensor of the present invention has been named a double-headed mass sensor.
The double-headed mass sensor of the present invention can sense change in the mass of a diaphragm by measuring a change in resonant frequencies caused by attaching a specific material on a diaphragm, and it is possible to sense change in resonance frequency due to change in the mass of the diaphragm itself; and therefore, the mass sensor can also be used as a thickness meter for vapor-deposited films or a dew indicator.
Furthermore, even if the mass of the diaphragm is not changed, the double-headed mass sensor of the present invention can also be used as a vacuum gauge, a viscosity meter, or a temperature sensor by placing it in an environment to cause change in resonant frequency, that is, by placing it in a medium environment of gases or liquids having different degree of vacuum, viscosity, or temperature.
Thus, although the double-headed mass sensor of the present invention can be used in various applications depending on its embodiments, the same basic principle is applied to the measurement of change in resonant frequencies of the diaphragm and the resonating portion including the diaphragm.
The double-headed mass sensor will be described below focusing on the case where it is used as an immunosensor.
BACKGROUND ART
Among what are referred to as diseases, microbiological examinations are recently essential for the treatment of diseases caused by microorganisms such as bacteria, viruses, or protozoa, to find their pathogens, to clarify their types, and to determine drugs to which they are sensitive.
At present, in the first stage of the microbiological examinations, since the cause of a disease and the type of the pathogen can be estimated from the symptoms, various specimens are selected depending on the type of the disease, pathogens present in the specimens are morphologically identified, or antigens or specific metabolites of pathogens (e.g., toxins or enzymes) existing in the specimens are immunochemically identified. Such processes include smeartests, staining, or microscopy used in bacterioscopy, and in recent years, instantaneous identification has become possible in this stage by fluorescent antibody staining or enzymatic antibody staining.
Also, the virus serological test, used in the detection of viruses, is a method for proving the presence of specific immune bodies (antibodies) that appear in the serum of a patient. For example, a complement fixation reaction is used in which the presence of antibodies or antigens is determined by adding complements to test blood, and by observing whether the complements react with antigens or antibodies in the blood and fix to the cell membranes of the antigens or antibodies, or destroy the cell membranes.
In the treatment of diseases caused by microorganisms or the like, as described above, adequate treatment can be conducted by finding pathogens in an early stage through the microbiological examinations described above, and the patient can be led to recovery without worsening of the condition of a disease.
However, with methods such as smeartests, staining, and microscopy, the detection of microorganisms is often difficult depending on their quantities, and time-consuming treatment such as the culture of specimens on an agar medium must be conducted as required. Also in the virus serological test, since measurements must usually be performed during both the acute stage and the convalescent stage for determination from the changes in the quantities of antibodies, there is the problem of time consumption from the point of view of prompt diagnosis.
Therefore, as seen in complement fixation reactions described above, when a substance to be sensed reacts with a catching substance which catches the substance to be sensed by reacting only with a specific substance to be sensed, microorganisms, the mass of the catching substance increases by the mass of the substance to be sensed, even slightly, and considering such a fact, the detection of pathogens is considered to be possible by the measurement of such a change in the mass. Such an increase in the mass similarly occurs in the relationship between a catching substance and a chemical substance such as a specific gaseous substance and a smell component, and also applies to the case where a substrate itself without change in the mass is a catching substance, on which a specific substance is deposited or added. On the contrary, when a reaction in which a substance to be sensed caught by a catching substance or the like is released, the mass of the catching substance or the like slightly decreases.
As an example of a method for sensing change in such a small mass, U.S. Pat. No. 4,789,804 discloses in
FIG. 22
thereof a mass sensor
80
comprising a quartz oscillator
81
and electrodes
82
,
83
facing the quartz oscillator
81
. When any substance adheres externally on these electrodes
82
,
83
, the mass sensor
80
senses change in mass using change in the resonant frequency of the thickness slip oscillation (shear mode) of the quartz oscillator
81
in the direction of the surface of the electrodes. Since such a mass sensor
80
measures change in resonant frequency basically caused by change in the mass load on the quartz oscillator
81
, such a mass sensor
80
is considered to be able to be used also as a thickness meter for measuring the thickness or the growth of a vapor-deposited film, or a moisture meter.
However, when such a quartz oscillator
81
is used, since the part on which an external substance adheres and the part for detecting resonant frequency are in the same location, for example, the resonant frequency becomes unstable because piezoelectric properties of the quartz oscillator
81
itself vary due to the temperature of the specimen or change in temperature. Also, if the specimen is a conductive solution, when the mass sensor
80
is immersed unprotected in the specimen, a short-circuit between electrodes
82
,
83
may occur. Therefore, the mass sensor
80
must always be subjected to insulation such as resin coating.
Furthermore, various vibratory gyro sensors are disclosed in International Patent Application JP97/01094 in accordance with the Patent Cooperation Treaty, and their structures resemble the double-headed mass sensor of the present invention described below in appearance. Differences between such vibratory gyro sensor and the double-headed mass sensor of the present invention will be compared in the description of the embodiments of the double-headed mass sensor of the present invention.
DISCLOSURE OF THE INVENTION
The present invention aims to improve the properties of the mass sensor as described above.
According to the present invention, there is provided as a first double-headed mass sensor, a double-headed mass sensor characterized in that between a first connecting plate joined to a first diaphragm at respective sides and a second connecting plate joined to a second diaphragm at respective sides, a resonating portion comprising the first connecting plate, the second connecting plate, the first diaphragm, the second diaphragm, and a first sensing plate, and a main element being provided on at least one plane surface of the first sensing plate, bridged in the direction perpendicular to the joining direction of each of said connecting plates and each of said diaphragms, is joined to a sensor substrate at at least a part of sides of said first connecting plate and said second connecting plate.
Here, the main element is p
Kimura Koji
Ohnishi Takao
Takeuchi Yukihisa
Burr & Brown
Miller Rose M.
NGK Insulators Ltd.
Williams Hezron
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