MICROMACHINED CLARK OXYGEN-ELECTRODE

We have fabricated a miniature Clark oxygen electrode using micromachining. A glass substrate with a silver working electrode, gold counter electrode and Ag/AgCl reference electrode is bonded to a silicon substrate by field-assisted bonding. The substrate has anisotropically etched grooves to provide small cavities to accommodate an electrolyte solution. The oxygen-permeable membrane is made from FEP and affixed thermally to the substrate. The 90% response time is an average 30 s, the residual current at zero oxygen concentration is negligible and we obtain a very good linear calibration curve. Improving the FEP membrane adhesion gives an oxygen electrode capable of tolerating sterilization by steam. The oxygen electrode operates stably for 10 h. The electrode lifetime can be extended to 30 h by impregnating the electrolyte solution in a gel.