Micro-Lensed Negative-Curvature Fibre Probe for Raman Spectroscopy

We developed a novel miniature micro-lensed fibre probe for Raman spectroscopy. The fibre probe consists of a single negative-curvature fibre (NCF) and a spliced, cleaved, micro-lensed fibre cap. Using a single NCF, we minimized the Raman background generated from the silica and maintained the diameter of the probe at less than 0.5 mm. In addition, the cap provided fibre closure by blocking the sample from entering the hollow parts of the fibre, enabling the use of the probe in in vivo applications. Moreover, the micro-lensed cap offered an improved collection efficiency (1.5-times increase) compared to a cleaved end-cap. The sensing capabilities of the micro-lensed probe were demonstrated by measuring different concentrations of glucose in aqueous solutions.

Improving Consistency of Photobiomodulation Therapy: A Novel Flat-Top Beam Hand-Piece versus Standard Gaussian Probes on Mitochondrial Activity

The tremendous therapeutic potential of photobiomodulation therapy in different branches of medicine has been described in the literature. One of the molecular mechanisms for this treatment implicates the mitochondrial enzyme, cytochrome C oxidase. However, the efficacy and consistency of clinical outcomes with photobiomodulation treatments has been fiercely debated. This work was motivated by this need to improve photobiomodulation devices and delivery approaches. We designed a novel hand-piece with a flat-top beam profile of irradiation. We compared the beam profile versus a standard hand-piece and a fibre probe. We utilized isolated mitochondria and performed treatments at various spots within the beam, namely, the centre, left and right edge. We examined mitochondrial activity by assessing ATP synthesis with the luciferin/luciferase chemiluminescent method as a primary endpoint, while mitochondrial damage was assessed as the secondary endpoint. We observed a uniform distribution of the power density with the flat-top prototype compared to a wide Gaussian beam profile with the standard fibre and standard hand-piece. We noted increased production of ATP in the centre of all three beams with respect to the non-treated controls (p < 0.05). Both the fibre and standard hand-piece demonstrated less increase in ATP synthesis at the edges than the centre (p < 0.05). In contrast, ATP synthesis was increased homogenously in the flat-top handpiece, both in the centre and the edges of the beam. Fibre, standard hand-piece and the flat-top hand-piece prototype have discrete beam distribution characteristics. This significantly affected the mitochondrial activity with respect to their position within the treated areas. Flat-top hand-piece enhances the uniformity of photobiomodulation treatments and can improve the rigour and reproducibility of PBM clinical outcomes.

A Sensitive Fibre Optic Probe for Autofluorescence Spectroscopy of Oral Tongue Cancer: Monte Carlo Simulation Study

The objective of this paper is to determine the best optical probe configuration that would help to detect neoplastic lesions in oral tongue epithelial tissue. Three geometrical configurations are investigated. The first one is a single-fibre probe with different fibre diameters. The second one is a multitilted fibre probe that employs different tilting angles for emission and collection fibres. While the third one is a multidiameter probe that employs different fibre diameters and distances between the emission and the collection fibres. All probes were evaluated for their depth-limited sensitivity in the epithelium layer of the tongue. Probes that showed efficient sensitivities were then compared for their fluorescence intensities acquired from both tissue types. The sensitivity for the first two types of probes was found to be roughly comparable. However, the differentiation capability of the multitilted fibre probe between dysplastic and healthy tissue was found to be noticeably larger by 30% of that of the single-fibre probe. The third type showed more sensitivity to fluorescence emerging from deeper layers. Finally, the proposed configuration is presented and proved to achieve higher sensitivity for both superficial and deep layers.

Multimode fibre probe calibration

Multimode fibres (MMF) used in endoscopy have advantage of small diameter and flexibility, thus causing less damage to living animals. However, the imaging requires wavefront shaping techniques to obtain a sharp image despite the mode dispersion in the waveguide. We suggest version of transmission matrix calibration which uses internal modes of the waveguide and, thus, lessens requirements on the endoscopy apparatus removing the external reference path.