Development of a micro-planar Ag/AgCl quasi-reference electrode with long-term stability for an amperometric glucose sensor Original Research Article

This paper reports a micro-planar Ag/AgCl quasi-reference electrode (QRE) with long-term stability which is characterized by both long-term potential stability and practical immunity to interference species, and which has been applied for use with an amperometric glucose sensor for plasma glucose. For fabrication, we coated a silver/silver chloride (Ag/AgCl) electrode first with γ-aminopropyltriethoxysilane (γ-APTES) and then with perfluorocarbon polymer (PFCP). Tests demonstrate the new electrode’s ability to remain stable over an 82-day period in 150 mM KCl, and also show its imperviousness to the effects of interference species (1 mM KI and 1 mM KBr), pH, and serum. Furthermore, in tests for glucose concentrations in plasma samples, a good correlation coefficient, 0.954 (n=30, Y=1.02X+0.20), was demonstrated between results obtained with a clinical analyzer and those obtained with an amperometric glucose sensor that used the developed Ag/AgCl QRE, showing that the Ag/AgCl QRE functions well as a reference electrode for plasma samples.