A novel biosensor using a biochemo-mechanical gel

The volume change of N-isopropylacrylamide (NIPAAm)/acrylic acid (AA) copolymer gel with immobilized glucose oxidase (GOD) was used to construct a biosensor based on a novel principle. The sensor features autonomous operation without electricity or spectroscopic procedures. It consists of a compartment to incorporate the gel, a flow channel to fill a dye solution, and a polydimethylsiloxane (PDMS) diaphragm which separates the gel and the dye solution. A volume change caused by the enzymatic reaction was converted into the change in a liquid column length using the PDMS diaphragm. For concentrations of mM order, 1 min was enough to distinguish the concentrations. When the measurement time was limited within 10 min, the lower detection limit was 200 /spl mu/M. Undesirable buffering effect could be minimized by reducing the sample volume to 20 /spl mu/L.