Gas sensing by thermoelectric voltage fluctuations in SnO2 nanoparticle films

Experimental results of gas sensing by thermoelectric voltage fluctuation measurements in gas sensors are presented. The applied sensors consist of monodispersed SnO2 nanoparticles films, with a mean diameter of 20 nm. The voltage fluctuations in the sensor films were observed with and without external voltage bias and its power density spectrum exceeded at least a thousand times its thermal noise. The power density spectrum of the observed stochastic signal changed in different gases by a factor of three while the change of the sensor resistance was only 2-3%. The stochastic signal observed in the sensor without external voltage bias is caused by the temperature gradient in the film. The results show that thermoelectric fluctuations, without external voltage bias, can be applied for use in gas sensing.