Biosensing using split-ring resonators at microwave regime

A split-ring resonator (SRR) array is experimentally demonstrated for a biosensing device at microwave frequencies. Each SRR in the array is excited by a time-varying H-field component through a microstrip transmission line in which microwaves propagate in the quasitransverse electromagnetic mode. It is found that the resonant frequency changes due to the binding of biotin and streptavidin onto the surface of the SRRs. The observed change values represent around ΔfB=120MHz and ΔfB-S=40MHz, respectively. Finally, the SRR-based biosensing device suggests a few improvements for increasing sensitivity and describes its possible application.