Microgap Structured Optical Sensor for Fast Label-Free DNA Detection

This paper presents a new label-free DNA optical sensor based on the microgap structured Fabry-Perot interferometer. An optical cavity is formed by a microgap sealed between a singlemode fiber and a well-cleaved fiber end. The capture DNA is immobilized on the cavity end by layer-by-layer electrostatic self-assembly. This sensor detects the hybridization of target DNA with complementary capture DNA by observing the optical cavity thickness variation. Experimental results demonstrate that this sensor has a sensitivity of 6 nmol/ml and can identify a 2-bp mismatch.