電容式感濕元件及其使用方法

This invention provides a capacitor-based fluid sensing unit. The capacitor-based fluid sensing unit comprises a substrate, a first electrode configured on the substrate, a sensing layer configured on the first electrode, a second electrode configured on the sensing layer. More particularly, the second electrode is a porous electrode and the sensing layer is a porous layer with a thickness between 50nm and 5mm. As fluid diffuses from the second electrode to the sensing layer, permittivity of the sensing layer would be changed by the fluid contained therein. The subsequent change of capacitance of the capacitor-based fluid sensing unit can be used as information to obtain, based on the permittivity and the diffusion area, the volume of the fluid. On the other hand, heat generated by bias-voltage can be used to evaporate the fluid and dry the sensing layer. Once the sensing layer is dried by heat, the sensing layer can be reused.