Smart single-chip gas sensor microsystem

Research activity in chemical gas sensing is currently directed towards the search for highly selective (bio)chemical layer materials, and to the design of arrays consisting of different partially selective sensors that permit subsequent pattern recognition and multi-component analysis1,2,3. Simultaneous use of various transduction platforms has been demonstrated4,5,6, and the rapid development of integrated-circuit technology has facilitated the fabrication of planar chemical sensors7,8 and sensors based on three-dimensional microelectromechanical systems9,10. Complementary metal-oxide silicon processes have previously been used to develop gas sensors based on metal oxides11 and acoustic-wave-based sensor devices12. Here we combine several of these developments to fabricate a smart single-chip chemical microsensor system that incorporates three different transducers (mass-sensitive, capacitive and calorimetric), all of which rely on sensitive polymeric layers to detect airborne volatile organic compounds. Full integration of the microelectronic and micromechanical components on one chip permits control and monitoring of the sensor functions, and enables on-chip signal amplification and conditioning that notably improves the overall sensor performance. The circuitry also includes analog-to-digital converters, and an on-chip interface to transmit the data to off-chip recording units. We expect that our approach will provide a basis for the further development and optimization of gas microsystems.