Development of multi-well-based electrochemical dissolved oxygen sensor array

This paper describes a multi-well-based (24-well) electrochemical dissolved oxygen sensor (m-well ECDO sensor) array on a glass substrate, using Nafion as a solid polymer electrolyte. The designed m- well ECDO sensor array shares working electrodes, reference electrodes, and counter electrodes, to reduce the number of electrode pads to approximately one-fourth of its expected pad numbers (72 to 18), compared to the simply repeated 24 sensors. This m-well ECDO sensor array can simultaneously measure up to six sensors at individual crossing points of the row and column electrodes. The fabricated m-well ECDO sensor array showed good repeatability during five consecutive measurements at intervals of 100 s with a 2.4 μm thick Nafion membrane. The response time was about 10 s when the solution state changed from the air-saturated state to the zero-oxygen state, and the measured output current was about -1 μA and-20 nA in the corresponding states, respectively. The fabricated m-well ECDO sensor array was applied to measure the oxygen consumption rate of C2C12 cells for a cell metabolic study. The ratios of the uncoupled oxygen consumption rate (OCR) to the coupled OCR obtained from three sensors of the fabricated m-well ECDO sensor array were 2.16, 2.22, 2.18, which are higher than 1.71, 1.68, 1.73 obtained from of the XF-24 of Agilent Inc. in 5,000, 10,000, 30,000 cells, respectively. This indicates that using the fabricated m-well ECDO sensor array, variations in DO (dissolved oxygen) concentration due to cellular respiration can be effectively detected, even at low cell numbers.