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Recent developments in optical endomicroscopy (OEM) and associated fluorescent SmartProbes present a need for sensitive imaging with high detection performance. Inter-core coupling within coherent fiber bundles is a well recognized limitation, affecting the technology's imaging capabilities. Fiber cross coupling has been studied both experimentally and within a theoretical framework (coupled mode theory), providing (i) insights on the factors affecting cross talk, and (ii) recommendations for optimal fiber bundle design. However, due to physical limitations, such as the tradeoff between cross coupling and core density, cross coupling can be suppressed yet not eliminated through optimal fiber design. This study introduces a novel approach for measuring, analyzing and quantifying cross coupling within coherent fiber bundles, in a format that can be integrated into a linear model, which in turn can enable computational compensation of the associated blurring introduced to OEM images.

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. We demonstrated the specificity and utility of the imaging agent in escalating in vitro and ex vivo whole human lung models (n = 3), utilizing a bespoke fiber–based delivery and imaging device, coupled to a wide-field, two-color endomicroscopy system. Results The imaging agent (Merocy-Van) was specific to Gram-positive bacteria and enabled no-wash imaging of S. aureus within the alveolar space of whole ex vivo human lungs within 60 s of delivery into the field-of-view, using the novel imaging/delivery endomicroscopy device. Conclusion This platform enables the rapid and specific detection of Gram-positive bacteria in the human lung.

Fibre-based optical endomicroscopy (OEM) permits high resolution fluorescence microscopy in endoscopically accessible tissues. Fibred OEM has the potential to visualise pathologies targeted with fluorescent imaging probes and provide an in vivo in situ molecular pathology platform to augment disease understanding, diagnosis and stratification. Here we present an inexpensive widefield ratiometric fibred OEM system capable of enhancing the contrast between similar spectra of pathologically relevant fluorescent signals without the burden of complex spectral unmixing. As an exemplar, we demonstrate the potential of the platform to detect fluorescently labelled Gram-negative bacteria in the challenging environment of highly autofluorescent lung tissue in whole ex vivo human lungs.

UV region with the best results showing 0.9 A W −1 responsivity and 0.28/5.3 s rise/decay time. When following a vertical device structure with multiple layers this complexity adds to both fabrication cost and difficulty. [5a,6] We herein report the development of a carbon-based flexible wire-shaped perovskite photodetector. This flexible wire-shaped device performs exceedingly well under low light environments (11 A W −1 ) and is easily woven into composites due to its flexibility and small diameter (≈400 µm). Using a novel in-house fabrication method, we have developed a rapid, repeatable, and scalable annealing process to move closer toward the potential of multifunctional composite materials and embedded wire-shaped photodetectors. The photodetector's small size is critical given that any addition to a composite part cannot have a negative impact on its mechanical properties. There has been reported success with integrated wires in composites for structural health monitoring. [7] As these systems use light emissions at 585 and 617 nm, we have characterized our device under the same conditions.Given the large drop in performance for wire-shaped devices when compared to equivalent structures on planar substrates, fabrication techniques were targeted as a point of improvement; noting that there is no standard method for wire-shaped devices. [8] For comparison, doctor-blade, [9] spray, [10] and spincoating [11] are all well documented and established fabrication methods for perovskite planar devices. However, wire-shaped cell fabrication exhibits less developed solutions [8a,12] and does not benefit from the history of extensive research found for planar thin film cells. It has been shown that methyl ammonium lead iodide perovskite (MAPbI 3 ) necessitates alternative processing such as two-step deposition or solvent engineering methods to create a pinhole-free, continuous thin film adding additional complexity in the fabrication process. [13] However, using MAPbI 3 we have created a continuous thin film on a wire using the joule heating method that shows comparable electrical characteristics to planar rigid perovskite photodetectors.We have developed a first flexible wire-shaped perovskite photodetector using joule heating method for annealing perovskite on CNY that is repeatable, cost effective, and scalable. This method utilizes joule heating in order to uniformly control the temperature of the wire substrate. We believe we have presented a novel solution able to compete with planar device. To the best of our knowledge, no other publication on a wire-shaped perovskite photodetector on thread-like CNY has Organolead triiodide perovskite (CH 3 NH 3 PbI 3 ) is used extensively as the absorber material for both solar cells and photodetectors; however, the reported photodetectors are all planar and flexible planar devices. To the best of knowledge the first flexible wire-shaped perovskite photodetector is reported. The performance of the wire-shaped perovskite photodetector on carbon nanotube yarn (CNY) critica...

Microfluidics has emerged rapidly over the past 20 years and has been investigated for a variety of applications from life sciences to environmental monitoring. Although continuous-flow microfluidics is ubiquitous, segmented-flow or droplet microfluidics offers several attractive features. Droplets can be independently manipulated and analyzed with very high throughput. Typically, microfluidics is carried out within planar networks of microchannels, namely, microfluidic chips. We propose that fibers offer an interesting alternative format with key advantages for enhanced optical coupling. Herein, we demonstrate the generation of monodisperse droplets within a uniaxial optofluidic Lab-in-a-Fiber scheme. We combine droplet microfluidics with laser-induced fluorescence (LIF) detection achieved through the development of an optical side-coupling fiber, which we term a periscope fiber. This arrangement provides stable and compact alignment. Laser-induced fluorescence offers high sensitivity and low detection limits with a rapid response time making it an attractive detection method for in situ real-time measurements. We use the well-established fluorophore, fluorescein, to characterize the Lab-in-a-Fiber device and determine the generation of $$\sim$$ ∼  0.9 nL droplets. We present characterization data of a range of fluorescein concentrations, establishing a limit of detection (LOD) of 10 nM fluorescein. Finally, we show that the device operates within a realistic and relevant fluorescence regime by detecting reverse-transcription loop-mediated isothermal amplification (RT-LAMP) products in the context of COVID-19 diagnostics. The device represents a step towards the development of a point-of-care droplet digital RT-LAMP platform.

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Self-powered photodetectors (PDs) are suitable for application in smart systems, image sensing and optical communications. Herein, a self-powered PD based on triple cation lead-halide perovskite (TCLP) is reported. We showed the effect of bromide concentration on the optical and structural properties of the TCLP films. Additionally, an environmental stability test was conducted and it was found that TCLP with 10% Br can remain stable for up to 128 days after exposure to ambient air. Using this material, a self-powered perovskite PD was fabricated and demonstrated an impressive performance with a responsivity of 0.52 A W −1 , detectivity of 8.8×10 12 Jones, on/off ratio of 7.3×10 5 , and a rapid rise and decay time of 19 μs and 21 μs, respectively. This work offers a useful insight into the effects the fabrication method of the thin film plays in building low-cost, stable, and high-performance self-powered PDs for application in structural health monitoring, imaging, optical communication, and biomedical sensing.