A fiber optic-based biological sensor without photo-written reflective elements

New biological sensor based on an optical fiber containing nanoparticles in its core, an alternative to the optical fibers containing Bragg gratings usually used.

Over the past decade, there has been increasing interest in fiber optic-based biosensors due to their attractive features such as compact size, flexibility, low cost, and biocompatibility. The principle of detection is based on the immobilization of the substances to be detected on the surface of the fiber. Following this immobilization, the refractive index is modified which leads to a change in the properties of the light propagating in the core of the optical fiber.

The fibers developed until now are based on the inscription of a Bragg grating (FBG, Fiber Bragg Grating). This reflector reflects light at a wavelength depending on the refractive index. Biosensors based on Bragg grating have been shown to be suitable for biodetection and have shown high sensitivity. However, the fabrication of Bragg gratings inside the fiber core in a specific region is complex and is not scalable as it requires precise and controlled micro-positioning. Therefore, the possibility of mass production is limited due to the complexity of manufacture. In addition, for certain fiber configurations (measurement in transmission and not in reflection), it is necessary to deposit gold mirrors at the tip of the fiber as well as external polarization controllers.

INPHYNI collaborated with the University of Kazakhstan to develop an alternative solution, called reflectorless fiber because it does not contain Bragg gratings. Light detection is based on light backscattering (Optical Backscatter Reflectometry) induced by the presence of nanoparticles in the core of the fiber. Unlike Bragg grating fibers, “nano” fibers can be made much more simply, using the standard manufacturing process for telecommunications fibers. They are therefore perfectly suited to mass production.



Reflector-less nanoparticles doped optical fiber biosensor for the detection of proteins: Case thrombin

Marzhan Sypabekova, Arman Aitkulov, Wilfried Blanc, Daniele Tosi

Biosensors and Bioelectronics, octobre 2020

DOI : 10.1016/j.bios.2020.112365


Wilfried Blanc, wilfried.blanc@inphyni.cnrs.fr

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