Towards an optimized design for tetrapolar affinity-based impedimetric immunosensors for lab-on-a-chip applications

Electrochemical impedance detection of biomolecules relies on the electrode system used. The architecture of the metal electrodes, on top of which the biosensing materials and consequently the target molecules are immobilized, is of particular importance. A high and uniform sensitivity of the sensor to impedance changes in regions of interest is required. In this paper, the sensitivity of tetrapolar coplanar-electrode systems is investigated as a function of electrode position, with the use of FEM modeling. The results indicate, that bringing the inner two electrodes closer to the outer two, increases positive and reduces negative sensitivity regions with zero sensitivity to impedance changes always present on the electrode surface.