SAW gas sensor applying dispersion interdigital transducer

A technology of interdigital transducers and gas sensors, which is applied in the direction of analyzing fluids using sound waves/ultrasonic waves/infrasonic waves, and can solve problems such as poor stability, frequency jumps, and oscillator stop vibrations

Inactive Publication Date: 2012-11-28
TIANJIN UNIVERSITY OF TECHNOLOGY
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  • Abstract
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Problems solved by technology

The Q value is high, but the stability is poor, and there are problems such as oscillator stop and frequency jumping.

Method used

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  • SAW gas sensor applying dispersion interdigital transducer
  • SAW gas sensor applying dispersion interdigital transducer
  • SAW gas sensor applying dispersion interdigital transducer

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specific Embodiment approach

[0027] 1. Designed to receive IDTs. For example, the number of interdigital pairs of receiving interdigital transducers is 30 pairs, and the electrode width and electrode interval are equal to 2.4 μm. When the piezoelectric film is made of AlN piezoelectric material, the phase velocity of SAW is about 5280m / s. The width of an electrode plus the width of the interval between two electrodes is used as a SAW wavelength λ, such as figure 1 As shown, the center frequency f0=550MHz of the receiving interdigital transducer can be calculated, and its bandwidth is 18.3MHz.

[0028] 2. Design the middle reflection grid. The width of the metal strips of the middle reflection grid is equal to the width of the interval between the metal strips. The width of the two metal strips plus the width of the two intervals is used as a SAW wavelength λ, such as figure 1 As shown, the total length of the intermediate reflection grid is 100-150 SAW wavelengths, that is, the number of metal strips is ...

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Abstract

The invention relates to an SAW gas sensor applying a dispersion interdigital transducer, which is a dispersive delay line gas sensor; no high delay line Q value composed of a dispersion interdigital energy transducer and a reception interdigital energy transducer is required, as long as intermediate reflecting gratings are enough, SAW frequency bands passing through the gratings are blocked to be narrow enough, and the Q value is high enough. Enough reflecting gratings can increase the area of a gas-sensitive membrane, increase the quantity of absorbed gas molecules, and thus increase sensor sensitivity. Compared with a resonator-type SAW gas sensor, the invention is a dispersive delay line gas sensor in nature, which has different detection mechanism from an SAW resonator, avoids the problems of oscillation stop and frequency jump of oscillators.

Description

【Technical field】 [0001] The invention relates to the technical field of SAW gas sensors, in particular to a SAW gas sensor using a dispersion interdigital transducer that can realize a new gas detection method. 【Background technique】 [0002] Gas detection means that in environmental detection, real-time and rapid detection of gas phase, liquid and other multi-parameter trace chemical substances is required; in modern medical diagnosis, sensors are required to identify and detect viral protein molecules within seconds in complex environments In the field of military security, sensors are required to perform real-time and high-precision detection of drugs and explosives, especially for the inspection of highly lethal biochemical warfare agents such as sand shower and mustard gas. There are two types of SAW gas sensors commonly used at present: delay line type and resonator type. [0003] The delay line type SAW gas sensor is composed of a surface acoustic wave delay line an...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N29/036
Inventor 杨保和郝银召王芳李翠平徐晟
Owner TIANJIN UNIVERSITY OF TECHNOLOGY
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