A Conjunctiva Oxygen Sensor for Transcutaneous Monitoring

A flexible and thin oxygen sensor was developed for transcutaneous oxygen monitoring at conjunctiva. The wearable oxygen sensor (width: 3 mm, thickness: 84 mum) was fabricated by pouching KCl electrolyte solution between non-permeable membrane and gas-permeable membrane with Pt-and Ag/AgCl-electrodes patterned using photolithography and sputtering. This wearable oxygen sensor was applied to electrochemical measurement with a constant voltage of -400 mV versus Ag/AgCl. This sensor was able to measure the dissolved oxygen with a calibration range from 0 to 7.31 mg/l. The sensor was also evaluated in gas phase by providing 60% oxygen and response time to reach 90% of the steady current after providing was approximately 45 seconds. Then the wearable oxygen sensor was applied to the transcutaneous oxygen monitoring at conjunctiva. The wearable oxygen sensor was attached to conjunctiva of a Japanese white rabbit. The rabbit inhaled atmospheric air and 60% oxygen, the output current of the sensor was monitored. Without warming, the sensor output increased and decreased synchronously with the change of oxygen concentration that the rabbit inhaled. This suggests that the sensor can be a new transcutaneous oxygen sensor without warming.