Integrated surface acoustic-wave and semiconducting-metal-oxide sensor array

Gas sensor development traditionally focuses on a single sensing platform that is optimized for a specific task. An ideal sensor is one that is completely sensitive as well as selective to the target gas of interest while being non- sensitive to interferent gases. Unfortunately, ideal sensors do not exist. Sensor arrays expand on the single sensor concept by incorporating a number of sensor utilizing the same sensing technology to provide a fingerprint of the particular measurand. Multiple sensor response are then analyzed with pattern recognition techniques such as neural networks. The limitation with single technology design methods is that single sensor limitations propagate. A sensor technology effective in detecting specific measurands may not be sensitive to related measurands. A novel sensor approach is underway that incorporates two sensing techniques, surface acoustic wave (SAW) and SMO, into an array of arrays. This integrated sensor array can provide marked improvements over either array alone in the increased bandwidth of measurands, the capability of cross verifying result with complimentary sensor technology responses, and the performance in the presence of interferents. Difficulties arise in the management, coordination and signal processing of the two methods. This is due to the fact that SAW_based sensor responded via a change in frequency, while SMO-based sensor response via a change in resistance. Each of these changes vary in magnitude proportional to the amount of analyte present. This paper will focus on aspects of: sensor selection, sensor data collection, manipulation, management, and processing for an integrated SAW and SMO sensor array.