Hollow Core Inhibited Coupling Fibers for Biological Optical Sensing

In this paper, we report how tube lattice hollow-core fibers can be successfully used to build sensors for molecule detection. The inner silica surface of the fiber is functionalized and coated with a probe layer, which permits to bond only with a particular molecule (the target). When the fiber is infiltrated with a solution containing the target, an additional layer is created on the silica surface, causing a redshift of the fiber transmission spectrum. The technique does not require any additional transducer component, such as Bragg gratings, amplifying techniques, such as nano-particles, nor coherent sources. It simply consists of the measurement of the transmission spectrum of a piece of fiber some tens of centimeters long. The principle is validated with experimental results showing the detection of the streptavidin protein. A solution containing streptavidin was flowed through the hollow core of the fiber coated with biotin. The measurement of the transmitted spectrum before and after the infiltration showed the presence of a few nanometer thick bio-layer.