ORGANIC MEMBRANES FOR MINIATURIZED ELECTROCHEMICAL SENSORS - FABRICATION OF A COMBINED PO2, PCO2 AND PH SENSOR

The on-wafer fabrication of a combined pO2, pCO2 and pH sensor is described. Photolithographic patterning of a polyacrylamide hydrogel and of a polysiloxane gas diffusion membrane has been optimized in order to achieve sensor characteristics suitable for use in a FIA set-up. The sensor has a typical sensitivity of 0.36 nA/Torr (pO2), 39 mV/decade (pCO2) and 51 mV/pH (pH), low drift and a functional lifetime of more than five weeks. The on-chip integrated polysiloxane flow-through channel closed on top by a glass plate forms a small detection cell (6 mul) allowing easy mounting of the detector and reducing the response time of the whole system to 90 s.