Computer-aided response time optimization of capacitive humidity sensors

This paper presents a MATLAB code which simulates the response of capacitive humidity sensors subjected to humidity variations. The sensors have parallel electrodes and dielectric polymer-based sensitive coatings. User-defined parameters regard the geometry of the sensor, the physical chemistry of sorption in the sensitive film and the environment of the sensor. The code includes electrostatic and gas diffusion calculation. The diffusion model is based on the theory of molecule diffusion in polymer films. The confrontation of this code with finite element simulation and experimental results demonstrates its accuracy. Experiments were carried out for DVS-BCB polymer films 1.3, 1.55 and 3.5 μm thick with various tipper electrode geometries. Although humidity sensors are dealt with in this paper, the code can be used for the optimization of capacitive sensors for other gases.