Analysis of biomolecule detection with optofluidic ring resonator sensors.

We theoretically and experimentally analyze the biomolecule detection capability of the liquid core optical ring resonator (LCORR) as a label-free bio/chemical sensor. We first establish a simple and general linear relationship between the LCORR's bulk refractive index sensitivity (BRIS) and its response to molecule deposition onto the surface, which enables us to easily characterize the LCORR sensing performance. Then, biosensing experiments are performed with bovine serum albumin (BSA) and LCORRs of various BRISs. The experimental results are in good agreement with the theoretical prediction. Further analysis shows that the LCORR is capable of detecting BSA below 10 pM with sub-picogram/mm2 mass detection limit.