Nanostructure-Enhanced Fiber-Optic Interferometry for Label-Free Immune Sensing

This paper proposes a nanostructure-enhanced fiber-optic interferometry (NSFOI) biosensor, combining the abilities of high sensitivity, real-time monitoring and in-situ measurement for label-free immunological detection, by employing high-aspect-ratio pillar-like nanostructures on the tip of sensor surface. The nanostructure layer, fabricated by a simple etching process on resonant cavity without mask patterning, was employed not only for the improvement of the detection limit to reach 1 ng/ml for rabbit-IgG (~6.7 pM) due to the increase of the biomolecular binding surface, but also for the enhancement of the optical path length to enlarge the maximum magnitude of fringe shift which was approximated to 1.4 nm by both experimental and theoretical results.