Spectral-domain optical coherence reflectometric sensor for highly sensitive molecular detection.

We describe what we believe to be a novel use of spectral-domain optical coherence reflectometry (SD-OCR) for highly sensitive molecular detection in real time. The SD-OCR sensor allows identification of a sensor surface of interest in an OCR depth scan and monitoring the phase alteration due to molecular interaction at that surface with subnanometer optical thickness sensitivity. We present subfemtomole detection sensitivity for etching of SiO(2) molecules and demonstrate its application as a biosensor by measuring biotin-streptavidin binding in a microfluidic device.