A unified bottom up multiscale strategy to model gas sensors based on conductive polymers

A multiscale bottom up procedure, based on an atomistic description, able to model the sensing mechanism of devices based on intrinsic conductive polymers (ICP) is described. The proposed procedure has been successfully applied to describe the response of devices based on polyaniline (PANI), the most widely used material for this application. In particular, using a recently developed Monte Carlo technique, atomistic PANI structures at different doping levels have been modeled. Thermodynamic and conductivity properties obtained from atomistic simulations have been bridged to a macroscopic modeling scheme, describing diffusion and reaction processes and, finally, the time dependent sensor response in good agreement with experiments. A similar scheme has been then adopted in order to understand at molecular level the effect of humidity in the sensor response. The proposed approach is general and can be extended to different or more complex systems giving a useful connection between the microscopic structure of the sensing material and the sensor behavior.