Needle-Type Glucose Biosensor Fabricated with Semiconductor Process: Utilization of a Novel Thin Film Ag/AgCl Reference Electrode and Plasma-polymerized Film

A needle-type glucose sensor was microfabricated aiming for mass production of high-quality disposable biosensors. Integrated detecting electrode patterns including a novel thin-film Ag/AgCl reference electrode were formed on a glass substrate by photolithography. The novel thin-film Ag/AgCl reference electrode could maintain a potential expected as a Ag/AgCl electrode in 1 M chloride solution for longer than 60 h. A plasma-polymerized film was used as a supporting layer in immobilizing an enzyme (glucose oxidase) on the sensitive area. The film is extremely thin and its adhesion to the substrate is excellent. Because functional groups such as amino groups can easily be incorporated in its highly-crosslinked network structure, immobilization of an enzyme can be performed easily and effectively. The greatest advantage is that the process can enable mass production of high-quality biosensors at a low cost.