Study on complex Td correction and Cole-Cole parameters for the impedance of immunobiosensor

Electric responses of impedance immunobiosensor for E. coli O157 : H7 at multi-frequencies were explored by complex Td factor correction method. The Corrected data were fitted using least-square method to get the Cole-Cole parameters, and then the relationship between the concentration of bacteria and these parameters was researched. The results showed that the complex Td correction could rectify the complex impedance data for the biosensor at all frequencies indeed, thereby eliminate the “Hook Effect” perfectly and reduced the interference of parasitic capacitance satisfactorily. In particular for impedance data at sweeping time equals to 120 seconds, the Cole-Cole parameters (R0, R∞, fc, ±) are very sensitive to the antigen concentrations. This would provide enriched and reliable information for the qualitative and quantitative test of bacteria with the biosensor.