A device and method for sensing fluid characteristics, including level, temperature, pH and chemistry, comprises a switch affixed to or embedded in a container of a size, shape and density such that said container floats stably in said liquid until a predetermined level is reached; the container...http://www.google.fr/patents/US5767775?utm_source=gb-gplus-shareBrevet US5767775 - Unanchored sensor and level sensor
