Patent ID: 6602401
Filing Date: 2003-08-05
Classification: G01N

Abstract:
A method for sensing presence of a gas in a liquid, comprising:forming a sensor housing with an open end and a chamber; mounting an anode and a cathode in the sensor housing; connecting the anode and cathode to a potential V to generate a sensor output current; covering the open end with a membrane having a first side facing the cathode and a second side in contact with the liquid; providing chamber electrolyte contacting the anode in the chamber; providing a channel between the cathode and the chamber electrolyte, the channel having inner and outer channel walls; providing channel electrolyte standing in the channel of length L and cross sectional area A between the cathode and the chamber electrolyte; and the channel electrolyte controlling a background sensor current level Ib; and selecting 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 Ib 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 +âˆ’1 part per billion.