Multispectral sensing of biological liquids with hollow-core microstructured optical fibres

Abstract

The state of the art in optical biosensing is focused on reaching high sensitivity at a single wavelength by using any type of optical resonance. This common strategy, however, disregards the promising possibility of simultaneous measurements of a bioanalyte’s refractive index over a broadband spectral domain. Here, we address this issue by introducing the approach of in-fibre multispectral optical sensing (IMOS). The operating principle relies on detecting changes in the transmission of a hollow-core microstructured optical fibre when a bioanalyte is streamed through it via liquid cells. IMOS offers a unique opportunity to measure the refractive index at 42 wavelengths, with a sensitivity up to ~3000 nm per refractive index unit (RIU) and a figure of merit reaching 99 RIU−1 in the visible and near-infra-red spectral ranges. We apply this technique to determine the concentration and refractive index dispersion for bovine serum albumin and show that the accuracy meets clinical needs.

Perfect Absorption and Refractive-Index Sensing by Metasurfaces Composed of Cross-Shaped Hole Arrays in Metal Substrate

“…Figure 7b shows the dependence of the position of the absorption peak on the refractive index. Conventionally, two important parameters, sensitivity (S) and figure of merit (FOM), are widely used to estimate the sensing performance [80][81][82][83][84]. S and FOM can be defined as:…”

“…Figure 7 b shows the dependence of the position of the absorption peak on the refractive index. Conventionally, two important parameters, sensitivity ( S ) and figure of merit ( FOM ), are widely used to estimate the sensing performance [ 80 , 81 , 82 , 83 , 84 ]. S and FOM can be defined as: where Δλ is the spectral shift of the absorption peak, Δ n is the change of the refractive index, and FWHM is the full width at half maximum of the perfect absorption peak.…”

SERS Platform Based on Hollow-Core Microstructured Optical Fiber: Technology of UV-Mediated Gold Nanoparticle Growth

“…The hollow-core microstructured optical fibers that were used have a hollow core diameter at around 240 um and three surrounding capillary layers. Spectral properties of such HC-MOF have been described previously [ 31 , 32 , 33 ].…”

“…Briefly, the deposition process was performed as follows: firstly, every fiber underwent 2 min plasma treatment, and its transmission spectra were measured. Then, PEi at concentration 2 mg/mL was delivered for 7 min at a speed of 150 mL/min using a peristaltic pump, as has been described previously [ 31 ]. Afterward, HC-MOF was washed for 2 min by deionized water and dried with air flow using a syringe; then, an hour later, the transmission spectrum was measured.…”

“…To verify the adsorption of functional materials onto fiber capillaries, we measured the optical transmission of functionalized fibers since the formation of nanocoating leads to the growth in the effective thickness of capillary walls and shifts in the fiber transmission windows towards longer wavelengths [ 31 ].…”