Localized Capture of Bacteria in an Interdigitated Electrode Impedance Biosensor

Abstract

This work presents the design of a biosensor for detection of Escherichia coli bacteria. The biosensor consists of an interdigitated electrodes array to detect the impedance changes, as a function of frequency, when bacteria is captured in different areas. The design was first simulated with COMSOL Multiphysics software to obtain the impedance magnitude and phase curves, after that the transfer function for every case was established with an algorithm in MATLAB software to propose an equivalent circuit in order to determine the electrical components that dominate the impedance response in every frequency range of the curve. Results show that impedance changes in the biosensor are mainly due to the bacteria captured between interdigitated electrodes, whereas the bacteria captured only over interdigitated electrodes produce a very small change in the impedance. In order to confine the bacteria between electrodes, a microchannel is added, increasing the biosensor sensitivity.