Label-free biosensor based on silicon-on-insulator micro-ring resonators

We propose a label-free biosensor based on concentric micro-ring resonators in silicon on insulator (SOI). The concentric micro-ring resonators offer another freedom to obtain deeper notches for higher detection sensitivity. The expanded modes also provide larger sensing area. A resonant frequency shift of ∼1.37 nm is demonstrated, by numerical simulations, between the situation of using a single strand DNA and a double strand DNA.