RU2492461C1 - Method of measurement of humidity - Google Patents

Abstract

FIELD: measuring equipment.

SUBSTANCE: on the sensor element on surface acoustic waves and on the reference device on the surface acoustic waves an interrogation signal is set, which is converted in the sensor element on the surface acoustic waves and the reference device on the surface acoustic waves. The amplitude of the signal envelope at the output of sensor element on the surface acoustic waves and the amplitude of the signal envelope at the output of the reference device on the surface acoustic waves is registered, and the amount of humidity is determined by the ratio of the amplitude of the signal envelope at the output of the sensor element on the surface acoustic waves and the amplitude of the signal envelope at the output of the reference device on the surface acoustic waves.

EFFECT: improvement of operation speed in measurement of humidity.

1 dwg

Description

The invention relates to the field of measurement technology and can be used in instrumentation and engineering for measuring moisture.

A known moisture sensing element is a delay line for surface acoustic waves (SAW) (Wireless passive SAW identification marks and sensors. L. Reindl, 2-nd Int. Symp. Acoustic wave devices for future mobile communicstion systems, Chiba univ., 2004 ), on the surface of which a moisture-sensitive material is applied. Structurally, the delay line consists of two interdigital converters (IDT) located on the piezoelectric board opposite each other. The delay time is used as an information signal.

The disadvantage of these moisture sensors is the large inertia of the humidity sensors.

A moisture sensing element is also known, which is a single-input resonator (V.V. Malov. Piezoresonance sensors, M .: Energoatomizdat, 1989 - 272 p.) On the surface of which a moisture-sensitive material is applied. Structurally, the resonator consists of an IDT structure and reflective structures located on both sides of the IDT. As an information signal, the intrinsic (resonant frequency of the resonator) is used. The disadvantage of these resonators, in relation to the measurement of humidity, is the large inertia of the humidity sensors.

The closest in technical essence to the invention is a moisture sensing element, which is a dispersive delay line (Wireless passive SAW identification marks and sensors. L. Reindl, 2-nd Int. Symp.Acoustic wave devices for future mobile communicstion systems, Chiba univ., 2004) on the surface of which a moisture-sensitive material is applied. Structurally, the dispersion delay line consists of IDTs and reflecting structures located on the piezoelectric board on one side of IDT in the form of a system of grooves with a variable period forming a dispersion structure. The delay time is used as an information signal. Compared to resonators and delay lines, a moisture sensor with dispersion structures has a higher sensitivity.

The disadvantage of humidity sensitive elements, which are a dispersion delay line, is also the large inertia of the humidity sensors.

The reason that impedes the obtaining of the technical result indicated below when using a well-known moisture sensitive element — the dispersion delay line —prototype for moisture measurement is the following disadvantage: a transition period (absorption or evaporation of moisture in a moisture-sensitive material when humidity changes in the environment) in a moisture-sensitive material not less than 5 s.

The objective of the present invention is to improve the performance when measuring humidity.

The technical result is achieved by the fact that a method for measuring humidity is proposed, which consists in the fact that a request signal is transmitted to a sensor on surface acoustic waves and to a reference device on surface acoustic waves, which is converted into a sensor on surface acoustic waves and a reference device on surface acoustic waves waves, while the amplitude of the envelope of the signal is recorded at the output of the sensing element on surface acoustic waves and amp ituda signal envelope at the output of a reference device of the surface wave and the humidity is determined by the ratio of the amplitude of the signal envelope at the output of the sensor for surface acoustic waves and the signal envelope amplitude at the output of the reference device on the surface acoustic waves.

As an information signal, the ratio of the amplitudes of the envelope of the signal at the output of the sensing element on the surface acoustic waves and the envelope of the signal at the output of the reference device on the surface acoustic waves is used.

A qualitative difference of the proposed method from analogues is the use of the physical effect of energy absorption of surfactants by liquids, while analogues use the effect of slowing down the speed of surfactants with special moisture-sensitive materials.

The invention is illustrated in the drawing, where:

figure 1 - shows the signal structure of devices on the surfactant when measuring humidity.

A method for measuring humidity is proposed, consisting in the fact that a request signal 1 is supplied to a sensitive element on surface acoustic waves and on a reference device on surface acoustic waves, which is converted into a sensitive element on surface acoustic waves and a reference device on surface acoustic waves, the amplitude of the envelope of the signal at the output of the sensing element on the surface acoustic waves A2 and the amplitude of the envelope of the signal at the output of the etalon of a device based on surface acoustic waves A1 and the humidity value is determined by the ratio A2 / A1 - the amplitude of the envelope of the signal at the output of the sensing element on the surface acoustic waves and the amplitude of the envelope of the signal at the output of the reference device on the surface acoustic waves.

In this case, a sensitive element on a surfactant for measuring moisture consists of a piezoelectric plate on which IDTs and reflective structures are formed. Reflective structures can be made in the form of a periodic system of grooves.

The piezoelectric plate can be made of a piezoelectric material (e.g., quartz).

The formation of IDT can be implemented using photolithography and etching technology. The formation of grooves of reflective structures can be realized by etching through a mask.

The method works as follows.

A request signal 1 is supplied to a sensitive element on surface acoustic waves and on a reference device on surface acoustic waves, which is converted into a sensitive element on surface acoustic waves and a reference device on surface acoustic waves, and the amplitude of the envelope of the signal at the output of the sensitive element on surface acoustic waves is recorded A2 waves and the amplitude of the envelope of the signal at the output of the reference device on the surface acoustic waves A1 and ve Jicin humidity is determined by the ratio A2 / A1 - the signal envelope amplitude at the output of the sensor for surface acoustic waves and the signal envelope amplitude at the output of the reference device on the surface acoustic waves.

When the humidity of the environment surrounding the piezoelectric plate changes, the humidity on the surface of the piezoelectric plate changes without delay.

The higher the concentration of liquid vapor (in particular water) on the surface of the piezoelectric board, the more the acoustic energy of the surfactant is absorbed and, accordingly, the lower the output signal of the sensitive element on the surfactant. At the same time, the reference device for surfactants does not respond to environmental humidity, since it is isolated from the environment.

As an information signal, the ratio of the amplitudes of the envelope of the signal at the output of the sensing element on the surface acoustic waves and the envelope of the signal at the output of the reference device on the surface acoustic waves is used.

Based on the calibration dependence (amplitude – humidity ratio), a change in the amplitude of the envelope of the signal at the output of the humidity sensor can correlate the value of humidity.

Thus, the proposed method for measuring humidity is a high-speed method for measuring humidity.

Information sources

1. Malov V.V. Piezoresonance sensors. M .: Energoatomizdat, 1989 - 272 p.

2. Wireless passive SAW identification marks and sensors. L. Reindl, 2-nd Int. Symp.Acoustic wave devices for future mobile communicstion systems, Chiba univ., 2004 - prototype.

Claims (1)

A method of measuring humidity, which consists in the fact that a request signal is transmitted to a sensor on surface acoustic waves and to a reference device on surface acoustic waves, which is converted to a sensor on surface acoustic waves and a reference device on surface acoustic waves, characterized in that the amplitude of the envelope of the signal at the output of the sensing element on surface acoustic waves and the amplitude of the envelope of the signal at the output of the reference a device surface acoustic waves and the humidity is determined by the ratio of the amplitude of the signal envelope at the output of the sensor for surface acoustic waves and the signal envelope amplitude at the output of the reference device on the surface acoustic waves.