US Patent 10398343 Perspiration sensor

A moisture sensor includes a pair of electrode plates separated by a moisture absorbent material that forms the dielectric of a capacitive sensor. As the absorbent dielectric material absorbs moisture, such as perspiration, the capacitance of the sensor changes reflecting a quantitative measure of perspiration absorbed. The sensor can be stabilized by capacitively coupling the dielectric material to the skin of the user to improve sensor stability and noise rejection. The sensor can include a capacitive sensing integrated circuit that measures the capacitance of the sensor in close proximity to the electrodes to limit the introduction of noise.