The Research Of Double-sided Diaphragm Micro Gas-preconcentrator

People are incresingly concerned about the quality of the surrounding environmentwith the development of people’s awareness of healthy and safety. Effective long-termmonitoring of the air quality is of great significance in the field such as air pollution andfoodsafety. Thus, it is necessary to set up a gas detection system which has a rapiddetection response to toxic volatile organic compounds even at low concentrations.However, it has been inevitably difficulties and challenges to improve the monitoringcapabilities for the explosive and toxic gases at low concentrations in the detectionsystem.eInstalled at the front-ed of the gas detection system as a collection device, thegas-preconcentrator is to improve the detection limits and sensitivity of detectionsystem. The selectivity and sensitivity can be greatly improved in the detection systemsuch as surface acoustic wave sensor (SAW) array, gas chromatography (GC), ionmobility spectrometry (IMS), the flame ionization detector (FID)，if the system is with agas preconcentator.In current gas detection systems, a major trend is making the gas detection systemminiaturization to a hang-held device. This paper describes the function of thepreconcentrator and a summary of the current development of MEMS-basedmicro-preconcentrator. Based on the planar micropreconcentrator, this paper designed adouble-sided diaphragm micro gas-preconcentrator in purpose of enhancing the rate ofpreconcentration and finally established the structure of the device by softwaresimulation and experimental exploration：Depositing the Pt resistance heated wire onthe Si3N4film, preparing the cavity and airflow channel through the deep reactive ionetching(DRIE), it is bonded or adhered to form a closed gas chamber. The4×4array ofdiaphragm micro-preconcentrator wiht a cell size of2mm×2mm is successfullyprepared. The sensor response increases6-8times with the preconcentrate at SAWtesting platform.The present experimental device fabrication is based on MEMS micro-machiningprocess including wet etching, dry etching, lithography, sputtering, evaporation coating process. Device test is carried out in the surface acoustic wave gas sensor platform.