A polyimide-based capacitive humidity sensor

The design of a relative humidity sensor is studied in which the principle of operation is based on the change of dielectric constant of a thin film of polyimide. The design of the sensor is established in such a way that it would be suitable for an integrated-circuit type of fabrication. The studies have shown that the experimental data are described well by the use of the Looyenga equation for dielectric constant behavior coupled with the Dubinin equation to describe the absorption as a function of relative humidity.