Disposable electrochemical capillary-fill device for glucose sensing incorporating a water-soluble enzyme/mediator layer

Abstract A novel disposable electrochemical capillary-fill device for glucose was fabricated using thick-film technology and incorporating a water-soluble layer bearing Os-complex mediator and glucose oxidase. A simple dual-electrode system used as a transducer consisted of three carbon stripes for a working electrode and an Ag/AgCl strip for a reference/counter electrode. The reagent ink, containing glucose oxidase, osmium–Tris(4,7-dimethyl-1,10-phenanthroline), and water-soluble binder, was drop-coated on the biosensor base material between the strips of the carbon electrode. The electrode part was covered with thin glass cover in order to construct a microliter electrochemical capillary-fill. A drop of test solution is automatically introduced to the microchannel by capillary action and then a water-soluble layer bearing glucose oxidase, the mediator and buffer salts becomes solubilized and quickly dispersed throughout the volume of the microchannel. The composition of the enzyme and mediator in the water-soluble layer was optimized. The constructed device showed a wide linear response range for glucose from 0.1 to 25 mM, fast response, and good storage stability. The present investigation showed that an efficient biosensor was constructed with an extremely low loading of enzyme and mediator.