BIPOTENTIOSTAT DRIVEN SENSOR (BDS) OXYGEN MEASUREMENT TECHNOLOGY

摘要

The BDS technology has been developed for measuring ppb level of oxygen in industrialrnprocesses. The sensor consists of four electrodes; a silver catalyzed gas diffusion sensingrnelectrode, a porous vitreous carbon blocking electrode(BE), a silver/silver oxide referencernelectrode(RE), and a platinum counter electrode(CE). The electrolyte is 10% potassiumrnhydroxide solution. The potentials of the sensing electrode and blocking electrode arerncontrolled by a bipotentiostat circuit at –0.9V and -1.1V vs. reference electrodernrespectively. Oxygen from the sample is reduced to hydroxyl anion at the sensing electrodernand a current is generated which is proportional to the oxygen concentration. Dissolvedrnoxygen and other impurities from the electrolyte are effectively blocked by the blockingrnelectrode from interference with oxygen measurement at the sensing electrode while thernhydroxyl anion can move through freely and be oxidized back to oxygen at counterrnelectrode. There is no net change of the electrolyte composition during the oxygenrnmeasuring process. The sensor exhibits high stability and sensitivity for ppb level ofrnoxygen measurement.