Characterization of Humidity-Sensors based on Polymer Sensing Layer

In this study various electrical properties of humidity sensors based on polyimide (PI) layer were characterized. The sensors were manufactured at the Fraunhofer Institute for Microsystems and Solid-State Technology (EMFT) as Inter Digital Transducers (IDT) with a polyimide layer. Changes in the electrical properties were due to a change in the permittivity of the PI layer under different environmental conditions. Using Wafer Prober, EMFT sensors were characterized at different temperatures and bias voltages. The capacitance measurements were conducted for a frequency range from 1 kHz to 1 MHz at the Fraunhofer EMFT. Two reference sensors were compared with HAST (Highly Accelerated Stress Test) built-in sensors to monitor humidity and temperature inside the HAST chamber. Afterward, EMFT sensors were tested at 130 °C and 85 % RH inside the HAST chamber.