In-situ detection of density alteration in non-physiological cells with polarimetric tilted fiber grating sensors

Abstract

Tilted fiber Bragg grating (TFBG) biosensors can be used as a cost-effective and relatively simple-to-implement alternative to well established biosensor platforms for high sensitivity biological sample measurements in situ or possibly in vivo. The fiber biosensor presented in this study utilizes an in-fiber 12° tilted Bragg grating to excite a strong evanescent field on the surface of the sensor over a large range of external medium refractive indices. The devices have minimal cross-sensitivity to temperature and their fabrication does not impact the structural integrity of the fiber and its surface functionalization. Human acute leukemia cells with different intracellular densities and refractive index (RI) ranging from 1.3342 to 1.3344 were clearly discriminated in-situ by using the differential transmission spectrum between two orthogonal polarizations for the last guided mode resonance before "cut-off", with an amplitude variation sensitivity of 1.8 × 10(4) dB/RIU, a wavelength shift sensitivity of 180 nm/RIU, and a limit of detection of 2 × 10(-5)RIU. The detection process was precisely controlled with a micro-fluidic chip which allows the measurement of nL-volumes of bio-samples. The proposed in-fiber polarimetric biosensor is an appealing solution for rapid, sub-microliter dose and highly sensitive detection of analytes at low concentrations in medicine, chemical and environmental monitoring.

Sensitive detection of C-reactive protein using optical fiber Bragg gratings

“…Fiber Bragg gratings are efficient optical devices in the field of biosensors (Tripathi et al, 2012;Guo et al, 2014), with the Bragg wavelength (λ B ) and the transmission intensity as probing parameters. Sensitivity of FBG sensors can be enhanced by etching the cladding layer and exposing the core directly to the surrounding medium.…”

Graphene-coated tilted fiber-Bragg grating for enhanced sensing in low-refractive-index region

“…in the fiber cladding. Hence, combining with its unique and rich spectral characteristics, TFBG is a promising alternative in SRI or biochemical-sensing fields [1,4,5], but in the region around the refractive index of water where most biochemical applications' interest is, it has a low sensitivity [6,7]. This issue can be improved by increasing the tilted angle, which shifts the cladding-mode envelope of TFBGs toward shorter wavelength and therefore enables the covering of the important region near 1.3 with the effective indices of the dominant cladding-mode resonances [3,8].…”

Ultrasensitive plasmonic sensing in air using optical fibre spectral combs

“…Fibre SPR refractometers with sensitivities of ∼500 nm RIU −1 in aqueous solutions have been demonstrated17. Biochemical sensors based on the antibody/antigen affinity have also been reported for proteins and cell immunosensing1819202122. They present limits of detection and sensitivities that compete with the most sophisticated plasmonic-based sensing solutions2324.…”