SnO₂ Nanowire Based Aerosol Jet Printed Electronic Nose as Fire Detector

A smart fire detector preferably reacting before smoke breaks out and providing information about the substance going to start burning, is an unaccomplished hope for fire safety authority since decades. Here, we present an easy method to fabricate, hence cheap, smell detecting electronic nose (e-Nose) which is capable to operate as low cost smart detector for fire-related smells as an example application. Smell sensing in principle is achieved by measuring the resistance pattern of 16 sub-sensor elements combined on a single chip and a subsequent pattern recognition technique using multivariate data analysis. The sensing material of one single sub-sensor is SnO₂ nanowires, fabricated in a high temperature condensation process and dispersed on digital aerosol jet printed interdigitated Au structure. Assisted by UV illumination, the basic chip performance was characterized using laboratory gases, such as synthetic air, Isopropanol, CO and Benzene and the detection limit of the e-Nose exposed to Benzene was measured to be 2.2 ppm. It needs only 6.6 mW to activate such sensor for continuous operation. As an application of such system, a smart fire detector was demonstrated, which can not only detect the pre burning smell of several substances, but it can also identify previously taught patterns of burning smell of test substances like, cotton, beech, and PCB.