INTEGRATED ARRAY SENSOR FOR DETECTING ORGANIC-SOLVENTS

A new sensor array device has been designed to detect organic solvents ; it comprises an array of six interdigital sensors lying upon a micro machined 0.5 mu m thick silicon nitride membrane. There are three sepa rate micromachined cells with two sensors per cell. In each cell, a th in film platinum resistance thermometer/heater is sandwiched in the mi ddle of the silicon nitride layer in order to either monitor or contro l the temperature of the active layer. The array device has a low powe r consumption of approximate to 30 mW/sensor at 400 degrees C and is c apable of operating at temperatures in excess of 600 degrees C, making it suitable for inorganic (e.g., SnO2) as well as organic gas-sensiti ve materials. The sensor array device has been coated with both polyme rs and semiconducting oxides and its response to toluene, n-propanol a nd n-octane has been studied. The low power consumption and good therm al stability of this array device make it useful for application in po rtable gas monitoring equipment.