MEMS气体传感器简介(英文版)ppt课件.ppt

MEMS GAS SENSOR,COMPOSITION OF GAS SENSOR,CONTENTS,1、Introduction and Application2、The classification and the principle of sensor3、Processing and manufacturing sensor,INTRODUCTION AND APPLICATION,Gas detection in peoples production life applications is very extensive, especially in the aspects of safety in production, such as, mine operation, gas production and transportation. Gas sensor is directly related to peoples life and property safety.,INTRODUCTION AND APPLICATION,Microelectromechanical systems (MEMS) technology is the micro device manufacturing method based on the development of microelectronic technology, first in the accelerometer (加速度计), a pressure pickup (压力传感器) field. With the increase of film technology with Thin film technology (薄膜技术) development, in recent years the MEMS sensors have been widely concerned in the chemical gas detection.,INTRODUCTION AND APPLICATION,The following are some of the gas sensor：,INTRODUCTION AND APPLICATION,MEMS gas sensor is compared with the traditional detection method, has the advantages of small size, high sensitivity, fast response, easy to integrate and many other advantages, is one of the main direction of the future development of gas sensors.,THE CLASSIFICATION AND THE PRINCIPLE OF SENSOR,According to different detection theory can be divided into:1、 Based on the gas self photoacoustic spectroscopy and optical properties of MEMS gas sensor2、Gas sensors sensitive materials based on adsorption principle3、Gas sensor for inflammable and explosive gas catalytic combustion4、 Field Asymmetric Ion Mobility Spectrometry technology of gas sensor,THE CLASSIFICATION AND THE PRINCIPLE OF SENSOR,1、 Based on the gas self photoacoustic spectroscopy and optical properties of MEMS gas sensor：,Photoacoustic gas sensor consists of a modulated light source , photoacoustic cell , high sensitive microphone 3 main part of the system .,The principle of process：,THE CLASSIFICATION AND THE PRINCIPLE OF SENSOR,1) light gas specific modulation frequency, the gas molecule in its excited state;,2) by gas molecules induced by impact way to release the absorbed energy;,THE CLASSIFICATION AND THE PRINCIPLE OF SENSOR,The principle of process：,3) the heat effect generated gas collisions, gas heating expansion heat wave, its frequency and the same frequency modulation light;,4) high sensitive microphone sampling of the heat wave;,2、Gas sensors sensitive materials based on adsorption principle:,THE CLASSIFICATION AND THE PRINCIPLE OF SENSOR,Surface acoustic wave (SAW) gas sensor is Bryant et al in 1981 for the first time put forward the SAW for gas sensitive research, and design the SAW gas sensor model of gas sensitive layer adsorption. With the development of MEMS technology, the SAW gas sensor has been miniaturized, sensitivity, selectivity and other performance parameters have been improved.,THE CLASSIFICATION AND THE PRINCIPLE OF SENSOR,The principle of process：,1) SAW generator vibration, the receiver receives the vibration signal, and the phase sensitive detection circuit detection and accept the shock wave phase difference;,2) gas molecules attached to the film made of sensitive materials, conducting properties of materials change, phase two wave difference change.,The phase sensitive detection circuit,The principle of catalytic combustion type gas sensor from the gas sensor for methane, macro, CO and other inflammable and explosive gas detection.,THE CLASSIFICATION AND THE PRINCIPLE OF SENSOR,3、 Gas sensor for inflammable and explosive gas catalytic combustion:,THE CLASSIFICATION AND THE PRINCIPLE OF SENSOR,The principle of process：,When there are flammable and explosive gases in the air, gas molecules in the catalytic oxidation reaction catalyst surface, and emit heat. The thermistor temperature change can be converted to electrical signals, and the reference film compared to get gas volume fraction changes.,THE CLASSIFICATION AND THE PRINCIPLE OF SENSOR,4、 Field Asymmetric Ion Mobility Spectrometry technology of gas sensor,FAIMS technology is the technology of ion mobility spectrometry (IMS) based on the development of, gas sensor FAIMS technology can be used in many fields, such as atmospheric toxic gas detection based on, and has the feature of small volume accuracy.,THE CLASSIFICATION AND THE PRINCIPLE OF SENSOR,The principle of process：,1) carrier gas mixed with the sample ionization after ion gate to the ion drift region,2) at high (greater than 11 000V / cm) under the effect of alternating electric field, the migration velocity of different ions for nonlinear (nonlinear) changes, relevant, this change and ion characteristics therefore, ion high electric field can differentiate between low field mobility similar.,Alternating electric field to add a DC bias voltage, high electric field transfer effects offset detecting gas ions.,THE CLASSIFICATION AND THE PRINCIPLE OF SENSOR,The principle of process：,3) in the sample testing process to the DC bias voltage is analyzed in the sample gas composition of scanning.,PROCESSING AND MANUFACTURING SENSOR,In the processing of SAW gas sensor as an example,1) micromachined tuning fork,Processing method of machining micro fork is similar to the wishbone MEMS acceleration sensor, can adopt lithographic manner through the processing.,PROCESSING AND MANUFACTURING SENSOR,In the processing of SAW gas sensor as an example,2) thin films,Preparation of thin film by deposition will sensitive material ionized deposition on the substrate.,In the processing of SAW gas sensor as an example,PROCESSING AND MANUFACTURING SENSOR,3) package,In general, encapsulation of SAW gas sensor with MEMS device common.,THANK YOU!,