Capacitive gas sensor and preparation method

Abstract

The invention discloses a capacitive gas sensor. The capacitive gas sensor comprises a shielding layer, support columns, interdigital electrodes located above the support columns and a sensitive layerfilled between the interdigital electrodes, wherein the shielding layer is located below and around the gas sensor; when gas diffuses to the upper surface of the gas sensor, chemical or physical reaction occurs between the shielding layer and the sensitive layer, so capacitance between the interdigital electrodes is changed. According to the capacitive gas sensor and the preparation method provided by the invention, the influence of an electric field between the interdigital electrodes on an external circuit can be shielded, and the sensitivity of the sensor is remarkably improved by changingthe height of the sensitive layer and increasing an air gap between the supporting columns.

Description

technical field [0001] The invention relates to a capacitive gas sensor, in particular to a capacitive gas sensor and a preparation method. Background technique [0002] Traditional gas sensors use fork-valued electrodes and a gas-sensitive layer between the interdigital electrodes to detect external gases. In the gas sensor, a sensitive layer is filled between the interdigital electrodes. When the gas diffuses into the sensitive layer, the sensitive layer will react physically or chemically with the gas, which will cause a change in the capacitance between the interdigital electrodes, which can reflect the gas characteristics such as concentration. [0003] as attached Figure 1-2 As shown, the top view of the gas sensor in the prior art is as attached figure 1 As shown, the electric field distribution between the interdigitated electrodes is as follows figure 2 shown. The adjacent interdigitated electrodes are electrode 1 at one end of the sensor and electrode 2 at t...

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Problems solved by technology

However, it takes a long time and a long distance for the outside gas to diffuse to the position between the fork-value capacitors. Since the gas diffuses to the sensitive layer between the fork-value electrodes, it needs to diffuse a long distance. When it diffuses to the position between the fork-value electrodes where the electric field is concentrated, The amount of diffusion will gradually decrease, resulting in poor detection sensitivity

At the same time, the fork value electrode structure in the prior art will generate a large amount of fringe electric field, and its downward fringe electric field will affect the circuit below the sensor and generate parasitic capacitance

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