Screen-printed transcutaneous oxygen sensor employing polymer electrolytes

A disposable, transcutaneous oxygen sensor has been designed and implemented using screen-printing technology for all fabrication stages. The sensor incorporates an integral heating element to promote transcutaneous diffusion of blood gases so that a reliable estimation of arterial blood gas concentration can be obtained. The oxygen sensing part of the device consists of a screen-printed Clark cell implemented as electrodes, electrolyte and membrane. A three-electrode configuration is employed with gold working and counter electrodes and a silver/silver chloride reference electrode. Several different polymer electrolyte and membrane materials were evaluated in the construction of the device, and their performances were compared. A fully automated gas testing rig was constructed to enable oxygen levels to be varied under computer control. Cyclic voltammetry and static analysis of the sensors were carried out at different oxygen concentration levels and in various test environments. Linear relationships were established with an averaged sensitivity level of 0.02 microA(mmHg)(-1) and high regression coefficients of 0.99. The prototype covered with a polytetrafluoroethylene membrane gave the experimental result of I (microA) = -0.025PO2 (mmHg) - 0.085. Several factors influenced the performance of the sensors. The investigations have greatly contributed towards an understanding of the suitability of the materials in achieving a viable, low-cost sensor.