Label-free DNA biosensor based on doubled tilted fiber Bragg grating

The realization of a DNA biosensor based on Double Tilted Fiber Bragg Grating (DTFBG) for label-free detection has been demonstrated. To our knowledge this is the first time that a biosensor has been realized with such kind of device. The surface of the optical fiber has been functionalized with peptide nucleic acid (PNA) in order to capture DNA strands. The changes of the interference fringes visibility of the grating, due to the PNA-DNA binding, proved the occurred fiber hybridization. The re-use of the fiber for multiple measurements and the selectivity of the sensor have been also investigated.