Computational Fluorescence Suppression in Shifted Excitation Raman Spectroscopy.

Fiber-based Raman spectroscopy in the context of in vivo biomedical application suffers from the presence of background fluorescence from the surrounding tissue that might mask the crucial but inherently weak Raman signatures. One method that has shown potential for suppressing the background to reveal the Raman spectra is shifted excitation Raman spectroscopy (SER). SER collects multiple emission spectra by shifting the excitation by small amounts and uses these spectra to computationally suppress the fluorescence background based on the principle that Raman spectrum shifts with excitation while fluorescence spectrum does not.

Tri-mode optical biopsy probe with fluorescence endomicroscopy, Raman spectroscopy, and time-resolved fluorescence spectroscopy.

We present an endoscopic probe that combines three distinct optical fibre technologies including: A high-resolution imaging fibre for optical endomicroscopy, a multimode fibre for time-resolved fluorescence spectroscopy, and a hollow-core fibre with multimode signal collection cores for Raman spectroscopy. The three fibers are all enclosed within a 1.2 mm diameter clinical grade catheter with a 1.

Sub millimetre flexible fibre probe for background and fluorescence free Raman spectroscopy.

Using the shifted-excitation Raman difference spectroscopy technique and an optical fibre featuring a negative curvature excitation core and a coaxial ring of high numerical aperture collection cores, we have developed a portable, background and fluorescence free, endoscopic Raman probe. The probe consists of a single fibre with a diameter of less than 0.25 mm packaged in a sub-millimetre tubing, making it compatible with standard bronchoscopes.

Time-Resolved Spectroscopy of Fluorescence Quenching in Optical Fibre-Based pH Sensors.

Numerous optodes, with fluorophores as the chemical sensing element and optical fibres for light delivery and collection, have been fabricated for minimally invasive endoscopic measurements of key physiological parameters such as pH. These flexible miniaturised optodes have typically attempted to maximize signal-to-noise through the application of high concentrations of fluorophores. We show that high-density attachment of carboxyfluorescein onto silica microspheres, the sensing elements, results in fluorescence energy transfer, manifesting as reduced fluorescence intensity and lifetime in addition to spectral changes.

Molecular detection of Gram-positive bacteria in the human lung through an optical fiber-based endoscope.

Purpose: The relentless rise in antimicrobial resistance is a major societal challenge and requires, as part of its solution, a better understanding of bacterial colonization and infection. To facilitate this, we developed a highly efficient no-wash red optical molecular imaging agent that enables the rapid, selective, and specific visualization of Gram-positive bacteria through a bespoke optical fiber-based delivery/imaging endoscopic device.

Methods: We rationally designed a no-wash, red, Gram-positive-specific molecular imaging agent (Merocy-Van) based on vancomycin and an environmental merocyanine dye.

Ultrafast-laser-ablation-assisted spatially selective attachment of fluorescent sensors onto optical fibers.

A robust method to selectively attach specific fluorophores onto the individual cores of a multicore fiber is reported in this Letter. The method is based on the use of ultrafast laser pulses to nanostructure the facet of the fiber core, followed by amine functionalization and sensor conjugation. This surface-machining protocol not only enables precise spatial selectivity, but it also facilitates high deposition densities of the sensor moieties.

Quantitative characterization of endoscopic imaging fibers.

We describe a technique for the quantitative characterization of endoscopic imaging fibers using an interference pattern as the standard object to be imaged. The visibility of the pattern at the other end of the fiber is then analyzed as wavelength and fringe period are varied. We demonstrate the use of the technique by comparing three fibers: two fabricated in-house from the same preform, designed to minimize inter-core coupling at visible wavelengths less than 650 nm, and a commercial imaging fiber.

Controlled core-to-core photo-polymerisation - fabrication of an optical fibre-based pH sensor.

The fabrication of fluorescence-based pH sensors, embedded into etched pits of an optical fibre via highly controllable and spatially selective photo-polymerisation is described and the sensors validated.