Glucose sensor using a microfabricated electrode and electropolymerized bilayer films.

A new type miniaturized glucose sensor with good selectivity and stable current response has been developed. The structure consists of a recessed rectangular microfabricated platinum electrode, inner layer of two electropolymerized nonconducting films, and outer bilayer of poly(tetrafluoroethylene) (Teflon) and polyurethane (PU) films. Glucose oxidase (GOx) is entrapped during the electropolymerization of a poly(m-phenylenediamine) (PMPD) film in an acetate buffer (AB) solution, on which a highly interference-resistive PMPD film is deposited in a phosphate buffered saline (PBS) solution. The second PMPD film causes no significant decrease in accessibility of glucose to GOx. The inner layer maintains less than 1% permeability to acetaminophen for 12 days. The fairly adhesive outer layer allows stable current response. Due to high permeability, the information about enzyme activity can be obtained without serious error in spite of outer layer intervening between enzymes and solution. The apparent Michaelis-Menten constant and the maximum steady-state current density were 24 mM and 80 microA cm(-2), respectively.