UV Absorption Spectroscopy in Water-Filled Antiresonant Hollow Core Fibers for Pharmaceutical Detection

Abstract

Due to a worldwide increased use of pharmaceuticals and, in particular, antibiotics, a growing number of these substance residues now contaminate natural water resources and drinking supplies. This triggers a considerable demand for low-cost, high-sensitivity methods for monitoring water quality. Since many biological substances exhibit strong and characteristic absorption features at wavelengths shorter than 300 nm, UV spectroscopy presents a suitable approach for the quantitative identification of such water-contaminating species. However, current UV spectroscopic devices often show limited light-matter interaction lengths, demand sophisticated and bulky experimental infrastructure which is not compatible with microfluidics, and leave large fractions of the sample analyte unused. Here, we introduce the concept of UV spectroscopy in liquid-filled anti-resonant hollow core fibers, with large core diameters and lengths of approximately 1 m, as a means to overcome such limitations. This extended light-matter interaction length principally improves the concentration detection limit by two orders of magnitude while using almost the entire sample volume—that is three orders of magnitude smaller compared to cuvette based approaches. By integrating the fibers into an optofluidic chip environment and operating within the lowest experimentally feasible transmission band, concentrations of the application-relevant pharmaceutical substances, sulfamethoxazole (SMX) and sodium salicylate (SS), were detectable down to 0.1 µM (26 ppb) and 0.4 µM (64 ppb), respectively, with the potential to reach significantly lower detection limits for further device integration.

Understanding Dispersion of Revolver-Type Anti-Resonant Hollow Core Fibers

“…Hollow core fibers (HCFs) allow for efficiently guiding light and are intensively investigated since they allow for accessing previously inaccessible fields for fiber optics or to substantially improve device performance within areas such as mid-IR gas lasers [1,2], broadband light sources [3,4], nonlinear optical effects [5], high-power pulse delivery [6], gas and liquid analytics [7,8], and pulse compression [9]. A comprehensive overview on HCFs can be found in Ref.…”

Optofluidics in Microstructured Optical Fibers

“…For instance, Mona Nissen et al introduced the concept of UV spectroscopy in liquid-filled anti-resonant hollow-core fibers to carry out the detection of pharmaceuticals, as shown in Figure 2 . The limit of detection (LOD) for sulfamethoxazole (SMX) and sodium salicylate (SS) reached down to 0.1 µM (26 ppb) and 0.4 µM (64 ppb), respectively [ 36 ].…”

A Dual Hollow Core Antiresonant Optical Fiber Coupler Based on a Highly Birefringent Structure-Numerical Design and Analysis

“…Over twenty years have passed since Cregan et al presented the first hollow-core optical fiber (HCF) with a microstructured cladding [1]. Remarkable optical features of HCFs [2][3][4] have resulted in their extensive experimental use, for example in telecommunications [5][6][7], gas and liquid spectroscopy [8][9][10][11][12][13], supercontinuum generation [14,15], high power optical beam delivery [16][17][18], transmission in the spectral regions unavailable for conventional fibers [19][20][21][22], biomedical applications [23,24], and many others. Although the overall scientific reach of both types of HCFs-namely hollow-core photonic bandgap and hollow-core antiresonant optical fibers (HC-PBFs and HC-ARFs, respectively)-has vastly exceeded that of conventional, step index fibers, their full potential is still to be discovered.…”