A side-heated silicon-based thin film catalytic hydrogen sensor and its processing method

Abstract

The invention provides a side-heated silicon-based thin-film catalytic hydrogen sensor. The hydrogen sensor is obtained through MEMS processing technology, and includes a silicon substrate. The upper surface of the silicon substrate is provided with a heat insulating layer, and one or more For the heat insulation tank extending to the heat insulation layer, the surface of the heat insulation layer is provided with a pair of heating coils composed of materials with a high temperature coefficient of resistance, and a catalytic film layer is provided on the inside, outside or above the heating coil, and the catalytic film layer is One surface is covered with a layer of high temperature resistant medium layer, the other surface is left blank, and the outer ring of the heat insulating layer is provided with a noble metal thin film resistor. The hydrogen sensor provided by the invention can work in two modes of catalytic combustion and heat conduction at the same time, and has small volume, low power consumption, fast response and long service life.

Description

technical field [0001] The invention belongs to the technical field of hydrogen sensors, and in particular relates to a side-heating silicon-based thin-film catalytic hydrogen sensor and a processing method thereof. Background technique [0002] The catalytic combustion gas sensor uses the thermal effect principle of catalytic combustion. The detection element and the compensation element are paired to form a measuring bridge. If it rises, the resistance of the platinum wire inside it will also increase accordingly, so that the balance bridge will be out of balance, and an electrical signal proportional to the concentration of combustible gas will be output. [0003] In order to improve the catalytic efficiency, the catalyst is usually made of a noble metal catalyst supported by porous alumina ceramics, usually olive-shaped or spherical, so it is called a bead element. The catalyst consists of very fine platinum filaments, usually only 25-50 microns. The diameter of the ca...

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Problems solved by technology

The diameter of the catalyst is about 0.5-1mm, and the platinum wire is easily broken under strong vibration; the noble metal catalyst supported by porous ceramics has a high response to all combustible gases, so it can only be used as a combustible gas sensor. Non-single hydrogen sensor

[0004] At the same time, the porous ceramics of the catalyst are very easy to absorb fine particles in the air, resulting in a significant decrease in the specific surface area of ​​the porous ceramics, and the catalytic activity is also greatly reduced. This means that the sensor needs to be calibrated regularly to correct errors, and the service life is also greatly improved. reduce

[0005] Our company's Chinese patent document "A Hydrogen Sensor and Its Processing Method" with the application number 201810220141.2 discloses a miniature hydrogen sensor that can measure any hydrogen concentration, making up for the shortcomings of the existing technology; making the hydrogen sensor selectivity, Issues such as security, stability, sensitivity, and weak output signals have been resolved to varying degrees

However, the stability and service life of the device still need to be further improved

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