Penetrating Microelectrode Sensor for In Situ Dissolved Oxygen Measurements

This paper describes a new penetrating micro-electrode array (MEA) sensor for in situ measurements of dissolved oxygen (DO) in bioapplications. The sensor was fabricated using an HF-based etching technique, with a polymerized polypyrrole layer as an insulator. The sensor area was formed by a gold layer inside a 1.7 mum recess at the tip of each microelectrode. Electrochemical performance of these DO MEAs was fully characterized by measuring DO of saline solutions with a Ag/AgCl reference electrode. The DO MEAs exhibited a rapid and linear response in the 0-9 mg/L (0-21% O₂) range. These new sensors are able to penetrate samples in order to perform measurements, and are ideally suited for in situ operations due to their small size.