A resonant poliyimide-based humidity sensor

A recently introduced type of humidity sensor uses the humidity dependent change of mechanical properties of polymer layers as sensing effect. To determine whether the mass increase of the resonating system or the swelling of the polymer material are the main causes of the humidity sensitivity, finite-element simulations are carried out and compared with measured results. The comparison of the results shows that, despite former assumptions, the swelling of the layer caused by sorption of water molecules mainly determines the humidity sensitivity of this type of sensor.