Evaluation of the Electrical Resistance Response of Insulating Glass Surface to Sense and Classify Humidity and VOCs Vapors

The research on new materials, fabrication processes, and characterization methods aims at obtaining sensors with low cost, high sensibility, and possibility of integration with electronic circuits. Recently, several works have focused on the development of gas sensors based on nanomaterials deposited on insulating platforms due to the remarkable sensing properties of such materials and simple device fabrication methods. However, the interference of such insulating platforms in the sensing properties of a miniaturized sensor becomes non-negligible depending on the dimensions, the type and amount of material, and the gas species analyzed. Thus, this paper proposes the use of interdigital aluminum microelectrodes patterned on a glass substrate to evaluate the influence of adsorption and desorption mechanisms of humidity and volatile organic compounds on this insulating surface. By analyzing the electrical conduction changes when the device is exposed to the mentioned vapors, we demonstrate that this influence is quite significant, as the electrical resistance of the glass insulating platform presented pronounced and fast resistance variation with repeatability and low drift. In addition, the selectivity among the experimented gas species was achieved by applying principal component analysis and supervised linear discriminant analysis classification methodologies, obtaining a success rate of 94% by using a cross-validation technique. The results show that the sensing properties of insulating platforms must be considered in some situations because they can affect the response of sensors based on nanomaterials deposited on insulating substrates.