A disposable electronic vacuum sensor capable of detecting a relatively low vacuum pressure of about 0.04 to 0.05 inches of water. The sensor includes a body having an LED and an opening at one end, and a channel extending longitudinally into the body from the opening. A power source is housed within...http://www.google.de/patents/US5517846?utm_source=gb-gplus-sharePatent US5517846 - Electronic vacuum sensor
