Integration of microfabricated needle-type glucose sensor devices with a novel thin-film Ag/AgCl electrode and plasma-polymerized thin film: mass production techniques

We developed an integrated array of needle-type biosensors employing a nove l process of fabrication, comprising conventional semiconductor fabrication and micromachining technology. Amperometric sensing electrodes with plasma -polymerized films and a thin-film Ag/AgCl reference electrode were directl y integrated on a glass substrate with thin-film process, e.g., sputtering. An enzyme was immobilized on the electrode via the plasma-polymerized film , which was deposited directly on the substrate using a dry process. The no vel thin-film Ag/AgCl reference electrode showed stable potentials in conce ntrated chloride solutions for a long period. The plasma-polymerized film i s considered to play an important role as an interfacial design between the sensing electrode and the immobilized enzyme considering that the film is extremely thin, adheres well to the substrate (electrode) and has a highly cross-linked network structure and functional groups, such as amino groups. The results showed increments of the sensor signal, probably because the p lasma-polymerized film allowed a large amount of enzyme to be immobilized. The greatest advantage is that the process can permit the mass production o f high-quality biosensors at a low cost.