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

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.