Devices and method of measuring a mass

• US 20050039532A1
• Filed: 08/13/2004
• Published: 02/24/2005
• Est. Priority Date: 08/19/2003
• Status: Active Grant

• Current Assignee: NGK Insulators Limited
• Original Assignee: NGK Insulators Limited
• Inventors: Ohsugi, Yukihisa, Okada, Naotake, Ishikawa, Seiji
• Granted Patent: US 7,140,255 B2
• Time in Patent Office: Days
• US Class Current: 73/580
• CPC Class Codes: G01G 3/16 measuring variations of frequency of oscillations of the body
• CPC Class Codes: G01N 2291/0256 Adsorption, desorption, surface mass change, e.g. on biosensors
• CPC Class Codes: G01N 2291/0426 Bulk waves, e.g. quartz crystal microbalance, torsional waves
• CPC Class Codes: G01N 2291/0427 Flexural waves, plate waves, e.g. Lamb waves, tuning fork, cantilever
• CPC Class Codes: G01N 29/022 Fluid sensors based on microsensors, e.g. quartz crystal-microbalance [QCM], surface acoustic wave [SAW] devices, tuning forks, cantilevers, flexural plate wave [FPW] devices microdevices per se B81B
• CPC Class Codes: G01N 29/024 by measuring propagation velocity or propagation time of acoustic waves

Abstract

A device 1 for measuring a mass comprises a vibrator 2, driving means 3A, 3B, 3C, 3D for exciting a basic vibration in the vibrator 2, detecting means 4A, 4B for detecting a displacement of vibration in the vibrator 2 and an adsorption film 5 capable of adsorbing a substance for detection. The mass is measured based on a difference between a detected value of the displacement of vibration obtained from the detecting means 4A, 4B when the mass is not measured and a detected value of the displacement of vibration obtained from the detecting means 4A, 4B when the mass is measured.

Claims

1. A device for measuring a mass, comprising a vibrator, a driving means for exciting a basic vibration in said vibrator, a detecting means for detecting a displacement of vibration in said vibrator, and an adsorption film capable of adsorbing a substance for detection,

wherein said mass is measured based on a difference between a detected value of said displacement of vibration obtained from said detecting means when said mass is not measured and a detected value of said displacement of vibration obtained from said detecting means when said mass is measured.

2. The device of claim 1, wherein dislocation of said basic vibration is substantially symmetrical with respect to the central axis of said vibrator.

3. The device of claim 1, wherein said detected value from said detecting means is substantially zero when said mass is not measured.

4. The device of claim 1, wherein said basic vibration is of thickness-twist vibration mode of said vibrator.

5. The device of claim 1, wherein said vibrator comprises at least one pair of bending vibration arms, and wherein said basic vibration comprises bending vibration of said bending vibration arms.

6. The device of claim 1, wherein said driving means comprises a driving electrode and said detecting means comprises a detecting electrode, and wherein a width “

L”

of said driving electrode is 0.2 times or more and 4.0 times or less of a width “

M”

of said detecting electrode.

7. The device of claim 1, wherein said driving means comprises a driving electrode and said detecting means comprises a detecting electrode, and wherein an area “

N”

of said driving electrode is 0.1 times or more and 3.0 times or less of an area “

O”

of said detecting electrode.

8. A method of measuring a mass using a device for measuring a mass comprising a vibrator, a driving means for exciting a basic vibration in said vibrator, a detecting means for detecting a displacement of vibration in said vibrator, and an adsorption film capable of adsorbing a substance for detection:

said method comprising the step of;

obtaining said mass based on a difference between a detected value of said displacement of vibration obtained from said detecting means when said mass is not measured and a detected value of said displacement of vibration obtained from said detecting means when said mass is measured.

9. The method of claim 8, wherein dislocation of said basic vibration is substantially symmetrical with respect to the central axis of said vibrator.

10. The method of claim 8, wherein said detected value from said detecting means is substantially zero when said mass is not measured.

11. The method of claim 8, wherein said basic vibration is of thickness-twist vibration mode of said vibrator.

12. The method of claim 8, wherein said vibrator comprises at least one pair of bending vibration arms, and wherein said basic vibration comprises bending vibration of said bending vibration arms.

13. The method of claim 8, wherein said driving means comprises a driving electrode and said detecting means comprises a detecting electrode, and wherein a width “

L”

of said driving electrode is 0.2 times or more and 4.0 times or less of a width “

M”

of said detecting electrode.

14. The method of claim 8, wherein said driving means comprises a driving electrode and said detecting means comprises a detecting electrode, and wherein an area “

N”

of said driving electrode is 0.1 times or more and 3.0 times or less of an area “

O”

of said detecting electrode.