2 × 3 array oxygen sensor for measuring cellular respiration level

This paper presents a microfabricated 2 times 3 array oxygen sensor integrated with heaters and temperature sensors for measuring cellular respiration level in a solution containing cells. The proposed oxygen sensor consists of 2 times 3 array Clark-type sensors, heaters, and temperature sensors on the substrate. Pt was used for temperature sensors, working electrode and counter electrode of Clark-type sensor because it has very stable physical and chemical properties and resistance linearity to temperature. Ag/AgCl was formed by electrochemical method on patterned Ag and used as reference electrode. Heaters as Au were patterned on the opposite side of the substrate. PDMS was coated on the acrylic plate by using spin coater, and PDMS thickness is about 18mum. It used as an oxygen permeable membrane of Clark-type sensor. The peak oxygen reduction current of the fabricated sensor was measured at -0.8 V by using cyclic voltammetry, and the 90% response time was about 10 sec from full-oxygen state to zero-oxygen state. The fabricated sensor showed good reproducibility for 1 hour with 3.15 nA standard deviation of 108.2 nA mean in the full-oxygen state and 0.14 nA standard deviation of 1.33 nA mean in the zero-oxygen state. Also, the fabricated sensor showed a good linearity with a correlation coefficient of 0.997. The temperature sensor showed an excellent linearity with a correlation coefficient of 0.999 from 32degC to 55degC.