Environment measuring device and environment measuring method

Patent metadata

Field	Value
Publication number	US-10444192-B2
Application number	US-201514938132-A
Country	US
Kind code	B2
Filing date	Nov 11, 2015
Priority date	May 24, 2013
Publication date	Oct 15, 2019
Grant date	Oct 15, 2019

Abstract

An environment measuring device 1 has a measuring QCM sensor 10, a reference QCM sensor 20, a measurement oscillation circuit 15, a reference oscillation circuit 25, a frequency counter 31, a humidity sensor 51, a control unit 40, and a storage unit 41. The measuring QCM sensor 10 has an oscillator and an electrode formed by a corrosive metal on the surface of the oscillator, and the reference QCM sensor 20 has an oscillator and an electrode formed by a corrosion-resistant metal on the surface of the oscillator. The storage unit 41 stores the measurement count signal, the reference count signal, and the humidity signal which are associated with a measurement time. The control unit 40 determines an amount of increase in mass due to the corrosion of the electrode of the measuring QCM sensor by using the measurement count signal and the reference count signal.

First claim

What is claimed is:

1. An environment measuring device comprising:
a measuring QCM sensor having an oscillator and an electrode formed of a corrosive metal on a surface of the oscillator;
a reference QCM sensor having an oscillator and an electrode formed of a corrosion-resistant metal on a surface of the oscillator;
a measurement oscillation circuit configured to transmit a measurement frequency signal having a frequency in accordance with a number of oscillations of the measuring QCM sensor as well as oscillating the measuring QCM sensor;
a reference oscillation circuit configured to transmit a reference frequency signal having a frequency in accordance with a number of oscillations of the reference QCM sensor as well as oscillating the reference QCM sensor;
a frequency counter that is connected to the measurement oscillation circuit and the reference oscillation circuit, counts a frequency of each of the measurement frequency signal and the reference frequency signal, and transmits a measurement count signal and a reference count signal each indicating a counted number;
a humidity sensor configured to detect humidity in an atmosphere and to transmit a humidity signal indicating the detected humidity;
a storage unit configured to store the measurement count signal, the reference count signal, and the humidity signal which are associated with a measurement time; and
a control unit configured to determine a mass increase amount due to corrosion of the electrode of the measuring QCM sensor by using an approximate expression calculated from measurement count signals and reference count signals indicating frequencies measured at humidity equal to or less than 60% and measurement time.

2. The environment measuring device according to claim 1 , wherein
the control unit uses a correction coefficient for correcting a difference in number between particles having adhered to the measuring QCM sensor and particles having adhered to the reference QCM sensor when determining a mass increase amount due to the corrosion of the electrode of the measuring QCM sensor.

3. The environment measuring device according to claim 2 , wherein
the correction coefficient is calculated from a ratio between magnitude of a mass fluctuation amount due to a moisture absorption—drying cycle of the particles having adhered to the measuring QCM sensor and the magnitude of a mass fluctuation amount due to the moisture absorption—drying cycle of the particles having adhered to the reference QCM sensor.

4. An environment measuring method comprising:
measuring a frequency of a measuring QCM sensor having an oscillator and an electrode formed by a corrosive metal on a surface of the oscillator when the measuring QCM sensor resonates with a measurement oscillation circuit;
calculating mass increase amounts of the measuring QCM sensor from a frequency of the measuring QCM sensor at humidity equal to or less than 60%;
measuring a frequency of a reference QCM sensor having an oscillator and an electrode formed by a corrosion-resistant metal on a surface of the oscillator when the reference QCM sensor resonates with a reference oscillation circuit;
calculating mass increase amounts of the reference QCM sensor from a frequency of the reference QCM sensor at humidity equal to or less than the 60%; and
determining a mass increase amount due to corrosion of the electrode of the measuring QCM sensor by using an approximate expression calculated from the mass increase amounts of the measuring QCM sensor, the mass increase amounts of the reference QCM sensor and measuring time.

5. The environment measuring method according to claim 4 , wherein
when determining the mass increase amount due to the corrosion of the electrode of the measuring QCM sensor, a correction coefficient for correcting a difference in number between particles having adhered to the measuring QCM sensor and particles having adhered to the reference QCM sensor is used.

6. The environment measuring method according to claim 5 , wherein
the correction coefficient is calculated from a ratio between a magnitude of a mass fluctuation amount due to a moisture absorption—drying cycle of the particles having adhered to the measuring QCM sensor and a magnitude of a mass fluctuation amount due to the moisture absorption—drying cycle of the particles having adhered to the reference QCM sensor.

Assignees

• Fujitsu Ltd

Inventors

• Takasu Ryozo

Classifications

• G01N5/02

  by absorbing or adsorbing components of a material and determining change of weight of the adsorbent, e.g. determining moisture content {(absorption bulbs B01D53/00)} · CPC title

• G01N29/022 Primary

  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 title

• G01N2291/0258

  Structural degradation, e.g. fatigue of composites, ageing of oils · CPC title

• G01N27/121

  for determining moisture content, e.g. humidity, of the fluid (moisture content of the tested material G01N27/048) · CPC title

• G01N29/036

  by measuring frequency or resonance of acoustic waves · CPC title