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 micromachined 0.5 mu m thick silicon nitride membrane. There are three separate micromachined cells with two sensors per cell. In each cell, a thin film platinum resistance thermometer/heater is sandwiched in the middle of the silicon nitride layer in order to either monitor or control the temperature of the active layer. The array device has a low power consumption of approximate to 30 mW/sensor at 400 degrees C and is capable of operating at temperatures in excess of 600 degrees C, making it suitable for inorganic (e.g., SnO2) as well as organic gas-sensitive materials. The sensor array device has been coated with both polymers and semiconducting oxides and its response to toluene, n-propanol and n-octane has been studied. The low power consumption and good thermal stability of this array device make it useful for application in portable gas monitoring equipment.