Development and optimization of a laser carbonized polyimide film as a sensor substrate for an all-polymer humidity sensor

摘要

Kapton~R polyimide film was studied as a viable sensor substrate using a capacitive type humidity sensor design. An argon ion laser was used to pyrolyze the Kapton~R film to form raised, carbonized filaments. Using a graphics program and a set of computer controlled servo mirrors, an interdigitated circuit was formed on the surface of the polymer. This circuit was coated with a hy-grosensitive polymer, HMPTAC (2-hydroxy-3-methacryloxypropyltrimethylammonium chloride), to form an all-polymer humidity sensor. The sensor substrate was optimized for sensitivity by varying pyrolysis wavelength and energy density. The results showed that the polyimide based sensor performed as well as the most commonly used silica/gold and alumina/gold sensor substrates.