Passive Resonance Roof Moisture Detector

A new, simple, and inexpensive prototype moisture sensor (patent pending) has been developed and tested in a small mockup of a low-sloped roof. The sensor comprises an inductor and a moisture-sensitive capacitor; it reqmres neither batteries nor wire connections. It is intended to be placed at locations within low- sloped roofs that might become wet from a leak, and remain operational for the life of the roof and automatically reset if the roof becomes dry again. The moisture state of the sensor can be detected by a simple electronic circuit that is passed within 30 cm of the sensor. Preliminary tests have been performed that indicate the potential for electromagnetically and remotely polling the sensor to determine moisture state. Further instrumentation to poll remotely the assemblage of sensors to detect the presence of some that are wet has been proposed and the principle tested; however, a practical implementation has not yet been developed.