Plasmonic biosensing with tilted fiber Bragg gratings interrogated using a 512-pixel spectrometer

Abstract

Plasmonic tilted fiber Bragg gratings (TFBGs) are very efficient for fast, accurate, and minimally invasive biosensing. Their transmitted amplitude spectrum is a dense comb of narrowband cladding mode resonances (full width at half maximum < 1 nm) that is usually demodulated using highly resolved (wavelength resolution < 10 pm) devices. This work demonstrates the possibility of using a coarsely resolved spectrometer (166 pm) to read out the amplitude spectrum of a gold-coated TFBG. A refined analysis of the spectral content has allowed us to develop signal processing that provides a refractometric sensitivity of 2656 nm/RIU. This is a fivefold improvement compared to previously reported read-out techniques. Biosensing has then been successfully implemented with gold-coated TFBGs implemented in reflection mode for the detection of insulin, with specific antibodies grafted on the gold surface. Our experimental work is a first step toward the industrialization of the FBG technology, as it opens the door to fast parallel biosensing, profiting from the multiple sensing channels (up to 64) of the interrogator and its high processing speed (repetition rate up to 3 kHz).

Gold Nanoparticle-Based Plasmonic Biosensors

“…It is beyond the scope of this review to give a comprehensive overview of all plasmonic biosensors as it is focused on those that make use of spherical AuNPs and only rely on the simple mixing of solutions. For example, plasmonic biosensors that use alloys of gold with other noble metals, nanomaterials with non-spherical shapes such as nanorods, electrochemical readout, gold layers, gold-functionalized fiber probes, surface-enhanced Raman scattering, microfluidic, lateral flow, and lab-on-a-chip devices are not covered here [ 71 , 72 , 73 , 74 , 75 , 76 ]. The selected examples described also report the sensitivity achieved by each method, which highlights the difficulty to compare the LOD across different techniques due to the use of different targets and different units [ 67 ].…”

Insulin detection using plasmonic optical fiber chips: a benchmark

“…TFBG spectra, characterized by cladding mode resonances spaced approximately 1 nm apart with a full width at half maximum (FWHM) of around 250 pm, traditionally required high-resolution interrogators with precision down to 1 pm. However, recent advancements have demonstrated the feasibility of reducing dependence on highly resolved spectrometers while preserving the integrity and sensitivity of SPR-TFBG spectra [20]. In this context, our current work aligns with the goal of making the technique more accessible, utilizing a high-speed FBG interrogator equipped with a cost-effective LED source and a 256-pixel spectrometer, operational within a 40 nm wavelength span, namely the BSI interrogator from B-SENS.…”