Cascaded silicon-on-insulator microring resonators for the detection of biomolecules in PDMS microfluidic channel

Silicon-On-Insulator (SOI) photonic microring resonators have shown promising potential for real time detection of biomolecules because of the sensitivity towards surface binding events. Previous work shows the use of single ring resonators for sensing applications. Each ring requires an input and output coupler and can be addressed only one at a time. We propose a novel use of cascaded ring resonators (width w = 200 nm and bending Radius R = 30 µm) together with a PDMS microfluidic network fabricated by soft lithography to expose each ring individually with different solutions. The SOI substrate with the planar waveguides and the PDMS with the microchannels are reversibly bonded to each other. The use of cascaded ring resonators offers the possibility to measure transmission spectra of multiple rings in different channels simultaneously. We measured Q-factors of >30'000 in air and >10'000 when exposed to water. Using a water/glycerin solution with known refractive indices we determine the sensitivity to be ~40 nm/RIU. Copyright 2011 Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.Applied Science, Faculty ofElectrical and Computer Engineering, Department ofReviewedFacult