Performance enhancement for an impedance biosensor with four-wire interdigitated microelectrode

In order to reduce the interfacial effects of biosensor effectively, a special planar interdigitated microelectrode for impedance biosensor was designed. A disposable immunosensor which integrated the immuno-chromatography assays was developed for E. coli O157:H7 detection. The four-wire interdigitated microelectrodes were used for sensing by electrochemical impedance spectroscopy (EIS). It allowed for conducting four-wire impedance spectroscopy as well as two-wire impedance spectroscopy. A simplified equivalent circuit of the four-electrode transducer was introduced for modeling the performance of the immunosensor. The antigen-antibody interactions with two-electrode and four-electrode measurements were analyzed to establish whether the four-electrode mode measurement technique could reduced the impedance related to the interfacial effects effectively. The results showed that the four-electrode mode measurement could more reliably measure the electrical response induced by the biospecific interaction by reducing the impedance related to the interfacial impedance. This biosensing method uses a low-cost disposable electrode, which have great potentials to be used to enhance the accuracy of impedance biosensor.