Polymeric ring resonators for label-free biosensing

We developed a biophotonic ring resonators for label-free biosensing. We first study an optimization approach for improving the optical performance of Su-8 based ring resonator. The effects of an ultrathin Su-8 under-layer are evaluated in terms of quality factor. An improvement of about 20% is obtained, as a consequence of the improved polymeric affinity between the substrate and the ring material. The biophotonic device is, than, integrated with polydimethylsiloxane (PDMS) microfluidic channel for biomolecule detection. The experimental results indicated that the ring resonators are able to detect the biomolecules of bovine serum albumin (BSA) after their immobilization on the Su-8 surface.