Finite-Element Simulation on Electrothermal Effects for Immuno-Biosensors

For a diffusion-limited protein, the diffusion boundary layer of the analyte formed on the reaction surface hinders the binding reaction from association and dissociation. With a non-uniform AC electric field, the electrothermal force generates a pair of stirring vortices to increase the transport of the analytes to the reaction surface and thus to enhance the association or dissociation of analyte-ligand complex. This work simulates a 2-dimensional full scale finite element analysis of the binding reaction kinetics of two commonly used proteins, CRP and IgG, by applying a non-uniform AC electric field. In addition to the electrothermal stirring effect, the blocking effect of the flow field due to the existence of the reaction surface at different positions of the micro-channel could cause different degrees of enhancement to the association and the dissociation. The largest enhancement is found at the position near the negative electrode. The initial slope of the curve of the analyte-ligand complex versus time can be raised up to 5.166 times for CRP and 1.934 times for IgG in association; and 3.744 times for CRP and 1.277 times for IgG in dissociation, respectively, with a field 15 V_rms peak-to-peak and operating frequency 100 kHz.