A micro amperometric immunosensor based on two electrochemical layers for immobilizing antibody

A micro amperometric immunosensor with a novel antibody immobilization scheme has been developed to detect human immunoglobulin G (HIgG). The microsensor was fabricated using standard silicon micromachining technique, with the sensitive area of only 2 mm₂ . A double exposure of SU-8 photoresist process was developed to create both the sensor pool and reaction pool. Antibody was immobilized using two-layer electrochemical polymers. Firstly polypyrrole was electropolymerized on the electrode as the transition layer. Then antibody and poly o-phenylenediamine were electropolymerized. This is a fast and simple method to immobilize antibody and is the first time to be used in amperometric immunoassay. At working potential of -0.3V, the immunosensor displayed a good linear dose-response behavior for HIgG concentrations between 5 and 355ng/ml. The response time was about 5 minutes