Label-Free Detection of DNA Hybridization Utilizing Dual S-Tapered Thin-Core Fiber Interferometer

A thin-core-fiber-based (TCF-based) dual S-tapered fiber sensor for label-free DNA hybridization detection has been proposed and experimentally demonstrated. The proposed biosensor is constructed by splicing a TCF of about 645 μm in length with two segments of single-mode fibers, and the two S-tapers are fabricated at the splicing joints by using a commercial fusion splicer. By functionalizing the fiber surface with monolayer poly-L-lysine and single-stranded DNA (ssDNA) probes, label-free detection of target ssDNA is achieved. The sensor functionalization and the hybridization processes for 1 nM target ssDNA are monitored through real-time analysis of the transmission spectral evolution. Owing to its compactness, low cost, fast response, real-time detection, and good specificity and repeatability, the proposed biosensor is expected to find potential applications in label-free biomolecule detection.