Planar amperometric oxygen sensor with improved preconditioning property

The feasibility of enhancing the preconditioning time property of the planar type amperometric oxygen sensor is investigated. A gas permeable membrane is formulated by incorporating hydrophilic polyurethane (HPU) into a one-component room temperature vulcanizing (RTV) silicone rubber matrix. Planar oxygen sensors are made by forming a recipient hydrogel layer on the base electrodes screen printed on a substrate, and by covering the hydrogel layer with a gas permeable membrane. The optimized RTV/HPU (70/30wt.%) yields a gas permeable membrane with fast water vapor transport that allows for fast hydration of the inner hydrogel layer, yet is not permeable to chloride ions that could interfere with oxygen measurements by changing the potential of the inner Ag/AgCl reference electrode. The proposed RTV/HPUbased planar oxygen sensor is shown to exhibit enhanced preconditioning time property (i.e. time required to reach 95% of the steady-state current=2s) with a sensitivity (slope: 1.1nA/mmHg) and a linearity (correlation coefficient: 0.999 in the range of 0.6-268mmHg) that are adequate for dissolved oxygen measurements in physiological samples.