Shaping of looped miniaturized chalcogenide fiber sensing heads for mid-infrared sensing

Chalcogenide fiber loop probe for the mid-IR spectroscopy of oil products

A theoretical approach based on the electromagnetic theory of optical fibers has been applied in the analysis of the evanescent modes of a chalcogenide fiber bend used as a probe in a fiber-based spectroscopic sensor, by the example of the detection of small amounts of an antigel additive in a diesel fuel. The absorbance of the loop probe calculated for each mode was compared with the results of spectrometer-based measurements. The role of the higher-order evanescent modes of a fiber bend has been revealed. The efficiency of using a loop probe has been shown to depend on conditions of light launching into the probe.

Early diagnosis of NAFLD-NASH transition using mid infrared spectroscopy

Non-alcoholic fatty liver disease (NAFLD) is defined as an excessive accumulation of fat in the liver in the absence of excessive drinking of alcohol. Initially considered as benign and self-limited, NAFLD may progress to the malignant stage of non-alcoholic steatohepatitis (NASH) characterized by degenerate hepatocellular ballooning and lobular inflammation. NASH can lead to hepatic fibrosis and ultimately to cirrhosis and hepatocellular carcinoma. Unfortunately, the transition from NAFLD to NASH is difficult to detect so far. In this paper, we propose to evaluate the characterization of NASH using mid infrared fiber evanescent wave spectroscopy on blood serum. We used an heuristic variable selection method and a generalized linear model to classify NAFLD and NASH spectra. The obtained results proved that this technique is a promising non-invasive and simple diagnosis tool for NASH.

Simultaneous Determination of Monoatomic Ions via Infrared Attenuated Total Reflection Spectroscopy in Aqueous Solution at Different Temperatures

In this study, monoatomic and thus IR-inactive ions were determined via infrared attenuated total reflection (IR-ATR) spectroscopy including Cl(-), Na(+), Mg(2+), Ca(2+), K(+) and Br(-), next to the IR-active ion [Formula: see text] The determination of IR-inactive ions is enabled, as each ion influences the infrared spectrum of bulk water by organizing the water molecules within the solvation shell around the ionic species in a unique way. Furthermore, the influence of temperature was taken into account for the potential application of this analytical technique in real-world scenarios. Using chemometric data analysis, seven ions could be discriminated at temperatures ranging between 3 ℃ and 45 ℃. Finally, within a sample of seawater, Cl(-), Na(+), Mg(2+) and [Formula: see text] could be simultaneously quantified, while the concentrations of Ca(2+), K(+) and Br(-) remained below the achievable limits of detection.

Chemotaxonomic discrimination of lichen species using an infrared chalcogenide fibre optic sensor: a useful tool for on-field biosourcing

Spectral analysis of lichen extracts obtained by MIR-FEWS permits to discriminate species and the identification of their major compounds. MIR-FEWS is a rapid, efficient and convenient tool for metabolic profiling.

A novel method for a fast diagnosis of septic arthritis using mid infrared and deported spectroscopy

OBJECTIVE

To assess the ability of mid infrared deported spectroscopy to discriminate synovial fluids samples of septic arthritis patients from other causes of joint effusion.

METHODS

Synovial fluids obtained from patients with clinically suspected arthritis were collected, analysed and classified according to standard diagnostic procedures as septic or non-septic. A spectroscopic analysis on synovial fluid samples was then performed using a coiled optical fiber made with chalcogenide glass. After a factorial analysis of the normalized spectra and the computation of a Fisher test used to select the most relevant components, a logistic regression model was fitted, allowing to attribute a score between 0 - non-septic -, and 1 - septic.

RESULTS

In a first phase, we analysed the synovial fluids from 122 different synovial fluids including 6 septic arthritis among arthritis of various origins. Septic synovial fluids were identified with a sensitivity of 95.8% and a specificity of 93.9% and an AUROC of 0.977. The analysis of an independent set of samples (n=42, including two septic arthritis) gave similar values.

CONCLUSIONS

Our data strongly supports the interest of mid infrared deported spectroscopy, which could be used potentially at point of care, for a rapid and easy diagnosis of septic arthritis. Now, the precision of the diagnosis must be evaluated through a multicentric study on a larger panel of patients.