Characterization of an O2 sensor using microelectrodes

This paper describes the response characteristics of a Clark type oxygen sensor using microelectrodes under a variety of operating conditions. The silicon based microelectrodes were fabricated using a CMOS process with Pt surface using a lift-off process. The Clark type sensor was configured using a three-electrode system. A set of four operating conditions with varying activation voltages, the use of oxygen-permeable membrane, and the use of different types of electrolyte layer, were experimented to determine suitable configuration for future integrated oxygen sensor designs. The results show that using Nafion as a solid state electrolyte and oxygen-permeable membrane provides the best linearity and sensitivity. The device was shown to have a good linear response with respect to dissolved oxygen concentration over a range of 0% to 100% with a correlation coefficient of 0.88 to 0.98. The oxygen sensor achieved a response time of 2-4 seconds, and consistent results over a long continuous operating time of at least 80 hours.