Abstract
A miniature Clark-type oxygen sensor for long-time continuous monitoring of oxygen concentration was fabricated using micromachining technology. The cathode electrodes are formed on a silicon chip, which is mounted on the top of a catheter of 1mm diameter using an oxygen permeable tube. In order that the oxygen sensors can operate for a long time, the cathode electrodes are insulated from the electrolyte with an organic and an inorganic film, and the cathode and the anode electrodes are sufficiently spatially separated in the sensor. Since the anode electrode is set at the end of the catheter filled with electrolyte, it is connected to the cathode electrically through holes formed on the cathode chip. The combination of silicone rubber and a thin film of amorphous Teflon as an oxygen gas permeable membrane not only shows a low drift in more than 120 hours continuous operation, but also maintains a stable response and a constant sensitivity after a long-time use.
