Sensing platform based on micro-ring resonator and on-chip reference sensors in SOI

This article presents work on a Silicon-On-Insulator (SOI) compact sensing platform based on Micro Ring Resonators (MRRs). In order to enable correction for variations in environmental conditions (temperature, mechanical stress etc), a study has been performed on the performance of uncoated sensing MRRs, and of SU8- and SiO2-covered reference MRRs. Excellent shielding for both cover materials has been obtained, however, water permeation into the SU8 causes a slow drift in sensor response. We believe that a user-friendly, low-cost and robust way for optical interfacing to MRR sensor chips is required for practical application in Point-Of-Care diagnostics, and that the cost and complexity of optical-electrical read-out systems must decrease. We have taken first steps to realize that vision, by building a prototype free-space optical coupling set-up, which enables non-photonic experts to characterize surface activation processes using MRRs. Moreover, we present our first steps towards on-chip read-out systems.