Flow through ring resonator sensing platform

This paper presents a novel sensing polymeric platform based on microring resonators with a direct microfluidic addressing scheme employing a flow-through approach. The fabrication of a hole placed in the centre of the ring allows precise analyte dispensing with an efficient transfer rate to the ring surface. The devices are exploited for biosensing experiments with bovine serum albumin (BSA) based solutions. The measured resonance peak shift shows a linear behaviour up to 200 nM. The sensor response time is measured by flowing 20 nM BSA solution at two different flow rates and in two different flow-through configurations. A reduction of more than one order of magnitude of the sensor response time, as compared with the standard flow-over approach, is obtained with the proposed flow-through approach thanks to improved transport kinetics of the analyte. The proposed device architecture, in its intrinsic simplicity, gives numerous advantages related to time responses and multiplexing of different analytes, selectively addressed to the ring resonators, for label-free biosensing.