Study On The Preparation And Characteristics Of Gas Sensor Based On Interdigital Electrodes

In recent years,the problem of environment pollution becomes more and more serious.Especially the poisonous and harmful gases momently threaten the living Environment of human being.So,it is particularly important to measure these toxic and harmful gases accurately,quickly and conveniently.Semiconductor gas-sensitive component has attracted more and more attention because of its advantages such as small volume,short recovery time and good repeatability among all the technology of gas detection.However,there still exist some problems such as poor selectivity,low response and high working temperature commercialization of sensors in commercial semiconductor gas sensor recently.Theses issues seriously restricts the practical application of semiconductor gas sensors.Based on this point,the preparation of interdigital electrode sensor was investgated in this paper,which combine semiconductor gas sensor technology with MEMS manufacturing process.Furthermore,the gas sensing properties of the gas sensor were measured by ammonia gas,nitrogen dioxide,formaldehyde and acetone.The results show that this sensor has high sensitivity,Short response time and good stabilization.The main contents are concluded as follows:Part one,we introduce the basic principle of interdigital electrode sensor and calculate the resestence of interdigital electrode.we can draw the conclusion that: the greater aspect ratio and density of the interdigital we get,the smaller initial resistance of the interdigital electrode can be abtained.According to the situation of our lab,we designed the parameters of the interdigital electrode,that is: A is 50 ?m,B is 50 ?m,C is 150 ?m and D is 20000 ?m.The aspect ratio is about 400,and the interdigital electrode has a total of 50 cycles.Part two,the silicon was chosen as the substrate material of the interdigital electrode,then throughing the silicon wafer cleaning,silica growth,uv etching process,such as fork electrode sensor,was successfully achieved and tungsten trioxide and fork refers to the electrode paste successful combination of the original fork refers to gas sensitive electrode was prepared.The interdigital electrode sensor was successfully fabricated by silicon wafer cleaning,silicon dioxide growth and UV lithography.The gas sensitive original of interdigitated electrode was prepared by combining the WO3 with the interdigital electrodes.Finally,the gas sensing properties of the interdigital electrode sensorb were tested by four kinds of gaseous pollutants.The experimental results show that: The sensor can get the maximum sensitivity 43.1 at optimal working temperature 200 ?,in 100 PPM ammonia and the recovery time of this sensor is no more than 5 seconds.However in 100 PPM nitrogen dioxide gas,the optimum working temperature is 250 ?and the the maximum sensitivity is 94.9,and the recovery time of this sensor is no more than 4 seconds.When the optimum working temperature turning to 50 ?,the sensitivity of the sensors are 16.8 and 4.8 in 100 ppm formaldehyde and acetone respectively.The increasing of working temperature has a little effect on the sensitivity of formaldehyde,but has a large effect on acetone.The sensor in formaldehyde environment,its response and recovery time is 5 seconds and 26 seconds,respectively and in acetone,its response time is 5 seconds and recovery time is 24 seconds.