Molding photonic boxes into fluorescent emitters by direct laser writing

We acknowledge financial support from the European Research Council Starting Grant ABLASE (ERC StG 640012), the Scottish Funding Council (via SUPA) and the European Union Marie Curie Career Integration Grant (PCIG12-GA-2012-334407). M.K. acknowledges funding from the EPSRC DTG (EP/M506631/1). S.H. gratefully acknowledges support from the Engineering and Physical Sciences Research Council through the ’Hybrid Polaritonics’ Program Grant (Project EP/M025330/1).Direct laser writing of photonic boxes into active layers of biologically produced recombinant fluorescent protein in optical microcavities is demonstrated. Irradiation with laser light above the photobleaching threshold induces photonic confinement potentials on the order of 40 meV. The technique provides high spatial selectivity and enables room-temperature lasing in protein rings, and circular and elliptical pillars with customized beam shapes.Publisher PDFPeer reviewe

Analysis of Relative Error in Perturbation Monte Carlo Simulations of Radiative Transport

SIGNIFICANCE: Perturbation and differential Monte Carlo (pMC/dMC) methods, used in conjunction with nonlinear optimization methods, have been successfully applied to solve inverse problems in diffuse optics. Application of pMC to systems over a large range of optical properties requires optimal placement of baseline conventional Monte Carlo (cMC) simulations to minimize the pMC variance. The inability to predict the growth in pMC solution uncertainty with perturbation size limits the application of pMC, especially for multispectral datasets where the variation of optical properties can be substantial. AIM: We aim to predict the variation of pMC variance with perturbation size without explicit computation of perturbed photon weights. Our proposed method can be used to determine the range of optical properties over which pMC predictions provide sufficient accuracy. This method can be used to specify the optical properties for the reference cMC simulations that pMC utilizes to provide accurate predictions over a desired optical property range. APPROACH: We utilize a conventional error propagation methodology to calculate changes in pMC relative error for Monte Carlo simulations. We demonstrate this methodology for spatially resolved diffuse reflectance measurements with ±20% scattering perturbations. We examine the performance of our method for reference simulations spanning a broad range of optical properties relevant for diffuse optical imaging of biological tissues. Our predictions are computed using the variance, covariance, and skewness of the photon weight, path length, and collision distributions generated by the reference simulation. RESULTS: We find that our methodology performs best when used in conjunction with reference cMC simulations that utilize Russian Roulette (RR) method. Specifically, we demonstrate that for a proximal detector placed immediately adjacent to the source, we can estimate the pMC relative error within 5% of the true value for scattering perturbations in the range of CONCLUSIONS: These findings indicate that reference simulations utilizing continuous absorption weighting (CAW) with the Russian Roulette method and executed using optical properties with a lo

Structured light imaging mesoscopy: detection of embedded morphological changes in superficial tissues.

SignificanceCurrent paradigms for the optical characterization of layered tissues involve explicit consideration of an inverse problem which is often ill-posed and whose resolution may retain significant uncertainty. Here, we present an alternative approach, structured light imaging mesoscopy (SLIM), that leverages the inherent sensitivity of raw spatial frequency domain (SFD) reflectance measurements for the detection of embedded subsurface scattering changes in tissue.AimWe identify wavelength-spatial frequency ( λ-fx ) combinations that provide optimal sensitivity of SFD reflectance changes originating from scattering changes in an embedded tissue layer. We specifically consider the effects of scattering changes in the superficial dermis which is a key locus of pathology for diverse skin conditions such as cancer, aging, and scleroderma.ApproachWe used Monte Carlo simulations in a four-layer skin model to analyze the SFD reflectance changes resulting from changes in superficial dermal scattering across wavelength ( λ=471 to 851 nm) and spatial frequency ( fx=0 to 0.5/mm). Within this model, we consider different values for epidermal melanin concentration to simulate variations in skin tone.ResultsMonte Carlo simulations revealed that scattering changes within the superficial dermis produce SFD reflectance changes which are maximized at specific ( λ-fx ) pairs and vary with skin tone. For light skin tones, SFD reflectance changes due to scattering reductions in the superficial dermis are maximized at λ=621  nm and spatial frequency fx≈0.33/mm . By contrast, for darker skin tones, maximal SFD reflectance changes occur at wavelengths in the near-infrared ( λ≥811  nm ) at a spatial frequency of fx≈0.25/mm . Interestingly, the change in SFD reflectance produced by such scattering changes is most uniform across all skin tones when using the longest wavelength tested ( λ=851  nm ) and a spatial frequency of fx≈0.22/mm . Taken together, our computational model identifies specific ( λ-fx ) pairs to optimally detect embedded structural alterations in the superficial dermis.ConclusionsThe findings establish the SLIM methodology as a means to detect morphological changes in an embedded subsurface tissue layer by leveraging inherent sensitivities of spatial frequency domain reflectance. This approach promises to enable simplified clinical tracking of subsurface microstructural alterations without the explicit need to consider an inverse problem approach

Structured light imaging mesoscopy for detection of embedded morphological changes in superficial tissues

This study introduces Structured Light Imaging Mesoscopy (SLIM), a novel non-contact optical method for detecting subsurface morphological tissue alterations. By leveraging the inherent sensitivity of spatial frequency domain (SFD) reflectance measurements, SLIM identifies specific wavelength-spatial frequency combinations that optimize the detection of scattering changes in the superficial dermis, a key area for various skin conditions. Monte Carlo simulations across a range of skin tones revealed that these optimal combinations vary with melanin concentration. Specifically, in subjects with lighter skin tones optimal sensitivity is achieved using shorter wavelengths and higher spatial frequencies, while for darker skin tones longer wavelengths and lower spatial frequencies are preferred. This approach simplifies clinical tracking of subsurface microstructural changes by eliminating the need for complex inverse problem solving, enabling rapid data acquisition and minimal processing

Optical Fiber Biosensor toward E-coli Bacterial Detection on the Pollutant Water

In this study, Zinc oxide (ZnO) nanorods based fiber optic biosensor has been reported for rapid and sensitive detection of Escherichia Coli (E-coli). A thin layer of Gold nanoparticles (Au) (around 50 nm) is coated on the tip of a multimode plastic optical fiber.  ZnO Nanorods are grown on Au layer thorough hydrothermal technique. This sensor showed a very fast response within the first 10 second of contacting the present of polluted water with E-coli Different concentrations of E. coli from (1000 to 4000 CFU/ml) have been tested and a sharp trend of sensitivity was observed. This sensing platform shows promising potential for regular water and food quality monitoring of various pathogenic microorganisms

A Review on The Second Edition of Farsi Biyamuzim

Despite the variety of electronic resources, textbooks continue to be the main medium of language teaching. Thus, criticizing them can improve the quality of education. This paper reviews the 1st volume of the 2nd Edition of “Farsi Biamuzim”, based on a set of standards and criteria for evaluating academic textbooks. Among the five criticism criteria of structure, content, language, method, and society and culture, the advantages of this work can be found in the general way of teaching the alphabet, providing innovative exercises, selecting practical topics, and designing useful topics in the content of lessons. Its disadvantages can be attributed to the structural inconsistency of the book in the instruction of letters and grammatical materials and the lack of a list of sources and a defect in its list of contents

Carbon quantum dot embedding silica–molecularly imprinted polymer coated optical fiber as ratiometric biosensors toward dopamine detection

We have developed a ratiometric fluorescence sensor for detecting dopamine (DA) using a silica-based molecular imprinting polymer (MIP) coated on cabbage-derived blue emissive carbon quantum dot (CQD) and deposited on optical fiber. Physicochemical characterization confirmed the successful integration of MIP and CQD, which created the selective lossy mode resonance (LMR) for DA monitoring. The experimental factors were optimized to obtain the maximum responses, and the sensing probe displays a dynamic response range of 0.3– 100μm and detection limit 0.027μm . This strategy was successfully applied to detect DA in red wine, coffee, apple, orange, and broad bean juices samples, with negligible cross-reactivity toward other potential interfering species (e.g., epinephrine, ascorbic acid, and uric acid). This novel rotational optical fiber-based sensor has promising potential and versatility for point-of-care, portable, and on-site sensing of environmental and biological samples

Detecting Subsurface Changes in Superficial Layered Tissues

This thesis explores characterization of subsurface changes in layered tissues, combining computational modeling advancements with the development and clinical application of a new optical imaging technique. First, it addresses limitations in perturbation Monte Carlo (pMC), a tool for solving inverse problems in diffuse optics. pMC calculates changes in light transport due to perturbations in tissue optical properties, using a baseline conventional Monte Carlo (cMC) simulation. A key challenge in applying pMC effectively lies in understanding the uncertainty associated with its predictions. This thesis addresses the need for robust uncertainty quantification in pMC predictions, improving the reliability of inverse problem solutions and enabling a better understanding of their limitations. However, inherent challenges of inverse problems in layered tissues motivates the development of alternative approaches that bypass the need for explicit inversion. Therefore, this thesis also explores the development of Structured Light Imaging Mesoscopy (SLIM), as an alternative approach leveraging the depth-sensitive capabilities of Spatial Frequency Domain Imaging (SFDI) to characterize layered tissues. We developed a predictive method for pMC variance changes based solely on reference simulation data. This method allows for the determination of optical property ranges within which pMC predictions maintain sufficient accuracy. We evaluated this methodology using spatially-resolved diffuse reflectance measurements with scattering perturbations up to ±20%. Our results demonstrate that reference simulations with lower (μ_s^')⁄μ_a values provide reliable perturbed estimates across a broader range of perturbation sizes. Furthermore, the proposed methodology exhibits greater accuracy in predicting pMC relative error for proximal detectors compared to distal detectors, with lower (μ_s^')⁄(μ_a) reference values extending the accurate prediction range. Implementing this approach to enhance pMC efficiency will significantly reduce computational costs in multi-spectral tissue analysis. We introduce SLIM, a novel optical characterization technique for layered tissues, which utilizes the sensitivity of spatial frequency domain (SFD) measurements without necessitating inverse problem solutions. SLIM identifies specific wavelength-spatial frequency (λ-fx) combinations that maximize sensitivity to optical property changes within a target layer. Monte Carlo simulations, employing a four-layer skin model, were used to analyze SFD reflectance variations resulting from alterations in the superficial dermal scattering coefficient. This analysis demonstrated that distinct SFD reflectance changes are maximized at specific (λ-fx) pairs, dependent on skin tone. For lighter skin, the optimal combination for detecting scattering reductions is approximately λ = 621 nm and fx ≈ 0.33 /mm. For darker skin, the optimal wavelength shifts to λ ≥ 811 nm with fx ≈ 0.25 /mm. Notably, λ = 851 nm at fx ≈ 0.22 /mm provides the most consistent sensitivity across all skin tones. The efficacy of SLIM was further assessed using clinical data from scleroderma patients. Clinical analysis revealed optimal spatial frequency and wavelength parameters for scleroderma monitoring within the ranges of fx = 0.15-0.2 /mm and λ = 811-851 nm, independent of subject skin tone. SLIM measurements employing these parameters demonstrated superior discrimination between diseased and healthy skin and exhibited a high correlation with the extent of disease progression in sclerodermatous tissue. Parallel Monte Carlo simulations, utilizing a multi-layered skin model that replicates scleroderma-related biological changes, corroborated these clinical findings. We posit that SLIM offers a quantitative and objective methodology for evaluating skin involvement in scleroderma. The identified optimal imaging parameters target relevant dermal depths, thereby enhancing sensitivity to biological alterations associated with scleroderma. In essence, this thesis starts with the development of a methodology to ensure the reliability of pMC predictions in diffuse optical applications; subsequently, the introduction of the SLIM framework for simplified subsurface change detection, obviating the need for complex inverse problem solutions; and finally, the demonstration of SLIM’s clinical applicability in assessing dermal alterations in scleroderma patients