A Room Temperature Polymer-Coated Piezoresistive Silicon Bridge Gasoline Vapor Sensor

This paper presents a novel gasoline vapor sensor, which is composed of a silicon bridge embedded with piezoresistive wheatstone bridge and a silicon rubber membrane as sensitive layer coated on silicon bridge. When the silicon rubber membrane absorbs gasoline vapor molecules from ambient air, the swelling of the silicon rubber membrane leads to bending of the silicon bridge diaphragm. The bending stresses could be transformed into an output voltage by a piezoresistive wheatstone bridge. It is found that silicon rubber membrane-coated silicon bridge vapor sensor exhibits a good sensitivity for gasoline vapor. Experimental results show that the sensitivity and resolution are 0.4 uV/ppm and 10 ppm, respectively. The detection limit is 50 ppm. The proposed gasoline vapor sensor has simply principle, mature technology, low cost, and can be integrated with signal processing circuit using the MEMS processes.