An apparatus for measuring an electrogastrogram and an intestinal electrogram including at least an electrode fixed to a body surface, an amplifier for amplifying a potential detected by said electrode, a low-pass filter for removing frequency signals other than the potentials of the stomach...http://www.google.com/patents/US5704368?utm_source=gb-gplus-sharePatent US5704368 - Method of, and apparatus for, measuring electrogastrogram and intestinal electrogram 
