High-performance humidity sensor with polyimide nano-grass

This paper presents a micro capacitive humidity sensor based on polyimide nano-grass with improved performance such as quick response and high sensitivity. These benefits come from the modification of polyimide surface morphology and dielectric constant. The nano-grass structure is created with plasma treatment on a polyimide layer to drastically enhance the water adsorption due to the increased surface to volume ratio. The plasma treatment also improves the surface chemistry useful for sensor performance. XPS and AFM analyses confirm the emergence of carbonyl groups responsible for the affinity of the treated surface to water molecules.