•Mid-infrared spectroscopy detects and discriminates specific bioprocess compounds.•Fibre-optic sensor allows real-time in-situ monitoring of bioprocesses.•Sophorolipid and glucose detection and ...monitoring over time in fermentation broth.•Discrimination of lactonic and acidic sophorolipids using a mid-infrared fibre-optic sensor.
This work proposes a simple, easy-to-fabricate and cost-efficient sensor based on mid-infrared (MIR) spectroscopy for in-situ real-time bioprocess monitoring. A process involving the production of sophorolipid biosurfactants by way of fermentation was studied with the aim of monitoring varying substrate and product concentrations over time and also distinguishing between the main two structurally different types of biosurfactant produced: lactonic and acidic sophorolipids. First, measurements were carried out using ATR-FTIR spectroscopy. This was followed by comparative measurements using a fabricated U-bent fibre-optic sensor designed for in-situ monitoring. It was demonstrated for the first time that varying concentrations of sophorolipids in a fermentation broth could successfully be monitored over time using an in-situ MIR fibre-optic sensor. Moreover, acidic and lactonic sophorolipids could simultaneously be identified at varying concentrations. The utilisation of such a sensor in bioprocesses can provide a wealth of real-time data, allowing for improved control of feeding rates and better process characterisation, providing significant opportunities for bioprocess control, resulting in increased production and decreased overall costs.
The increasing awareness of the harsh environmental and health risks associated with air pollution has placed volatile organic compounds (VOCs) sensor technologies in elevated demand. While the ...currently available VOC-monitoring technologies are either bulky and expensive, or only capable of measuring a total VOC concentration, the selective detection of VOCs in the gas-phase remains a challenge. To overcome this, a novel method and device based on mid-IR evanescent-wave fiber-optic spectroscopy, which enables enhanced detection of VOCs, is hereby proposed. This is achieved by increasing the number of analyte molecules in the proximity of the evanescent field
via
capillary condensation inside nano-porous microparticles coated on the fiber surface. The nano-porous structure of the coating allows the VOC analytes to rapidly diffuse into the pores and become concentrated at the surface of the fiber, thereby allowing the utilization of highly sensitive evanescent-wave spectroscopy. To ascertain the effectiveness and performance of the sensor, different VOCs are measured, and the enhanced sensitivity is analyzed using a custom-built gas cell. According to the results presented here, our VOC sensor shows a significantly increased sensitivity compared to that of an uncoated fiber.
Increased sensitivity of mid-IR evanescent field sensing for gas-phase volatile organic compound detection using a nano-porous coating of an optical-fibre.
The use of polyaniline emeraldine base films as antireflection coating for near and middle IR optics elements was studied. The optical quality of ZnSe substrates spin-coated with thin PANI EB layers ...were studied using a Linnik interferometer. The spectral properties of PANI coated ZnSe plates were investigated with FTIR spectrometer. It was shown that PANI coating allows a significant decrease of Fresnel losses in the near and middle IR bands (1.0–6.25
μm). The coating allowed continuous transmission of high power density (up to 3
W/mm
2) of IR radiation produced by CO
2 laser. The laser irradiation damage threshold of the PANI EB coating was studied at a wavelength of 1.5
μm. Microhardness of the coated ZnSe is established as satisfactory.
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