Patent ID: 7208071

Claim:
A sensor for sensing presence of a gas in a liquid, comprising: a sensor housing with an open end and a chamber; an anode and a cathode mounted in the sensor housing, the anode and cathode connecting to a potential V to generate a sensor output current; a membrane covering the open end, the membrane having a first side facing the cathode and a second side in contact with the liquid; chamber electrolyte contacting the anode in the chamber; a channel between the cathode and the chamber electrolyte, the channel having inner and outer channel walls, the channel having a length L and a cross sectional area A; channel electrolyte standing in the channel between the cathode and the chamber electrolyte; the channel electrolyte controlling a background sensor current level I b ; and wherein the channel has an area to length A/L ratio less than 0.026 mm so that the channel resistance is high enough to control the background sensor current level I b to below 5 nanoamperes per 40 microamperes of the sensor output current at a gas concentration of 8 ppm in the liquid to provide a sensing accuracy of approximately +−1 part per billion.