Densely packed microgoblet laser pairs for cross-referenced biomolecular detection

Microgoblet laser pairs are presented for cross-referenced on-chip biomolecular sensing. Parallel readout of the micro­lasers facilitates effective mutual filtering of highly localized refractive index and temperature fluctuations in the analyte. Cross-referenced detection of two different types of proteins and complete chemical transducer reconfiguration is demonstrated. Selective surface functionalization of the individual lasers with high spatial accuracy is achieved by aligned microcontact stamping

Epigenetic studies in children at risk of stunting and their parents in India, Indonesia and Senegal : A UKRI GCRF Action Against Stunting Hub protocol paper

ASR provided research and organisational support within the Action Against Stunting Hub (AASH) epigenetics theme and drafted and revised the manuscript. MN led the AASH epigenetic theme in Senegal and oversees the implementation of the epigenetic protocol and contributed to the development of the protocol and critically revised the manuscript. RRK led the AASH epigenetic theme in India and oversaw the implementation of the epigenetic protocol, contributed to the development of the protocol and critically revised the manuscript. MKH led the AASH epigenetic theme in Indonesia and oversaw the implementation of the epigenetic protocol, contributed to the development of the protocol and critically revised the manuscript. DYD was responsible for monitoring evaluation and learning on the hub, critically reviewed the protocol and revised the manuscript. LFA managed the implementation of the study in India, critically reviewed the protocol and revised the manuscript. NLZ managed the implementation of the study in Indonesia, critically reviewed the protocol and revised the manuscript. AD managed the implementation of the study in Senegal, critically reviewed the protocol and revised the manuscript. DY, TCA and MN are epigenetic researchers in Indonesia, critically reviewed the protocol and reviewed the manuscript. MG, DS, SSV and MM are epigenetic researchers in India, critically reviewed the protocol and reviewed the manuscript. GWH advised on the statistical aspects of the protocol and the power calculation and reviewed the manuscript. UF is the AASH project lead in Indonesia, contributed to study design and coordination of the study and thematic linkages; supervised drafting of the manuscript. BF is the AASH project lead in Senegal, contributed to study design and coordination of the study and thematic linkages and supervised drafting of the manuscript. BK is the AASH project lead in India, contributed to study design and coordination of the study and thematic linkages and supervised drafting of the manuscript. PH is the AASH project deputy lead and epigenetic theme lead who designed the study, drafted and revised the manuscript, carried out the statistical calculations.Peer reviewe

Label-Free Optical Single-Molecule Micro- and Nanosensors

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this recordLabel-free optical sensor systems have emerged that exhibit extraordinary sensitivity for detecting physical, chemical, and biological entities at the micro/nanoscale. Particularly exciting is the detection and analysis of molecules, on miniature optical devices that have many possible applications in health, environment, and security. These micro- and nanosensors have now reached a sensitivity level that allows for the detection and analysis of even single molecules. Their small size enables an exceedingly high sensitivity, and the application of quantum optical measurement techniques can allow the classical limits of detection to be approached or surpassed. The new class of label-free micro- and nanosensors allows dynamic processes at the single-molecule level to be observed directly with light. By virtue of their small interaction length, these micro- and nanosensors probe light–matter interactions over a dynamic range often inaccessible by other optical techniques. For researchers entering this rapidly advancing field of single-molecule micro- and nanosensors, there is an urgent need for a timely review that covers the most recent developments and that identifies the most exciting opportunities. The focus here is to provide a summary of the recent techniques that have either demonstrated label-free single-molecule detection or claim single-molecule sensitivity.Living Systems Institute, University of Exete

Modification of radiative rates of molecules coated on a single microcavity by evanescent coupling of whispering gallery modes (WGMs)

Dye-coated single microspheres exhibit whispering gallery modes (WGMs) within the spontaneous emission bandwidth of the dye spectrum. These modes are extremely sensitive to the size, shape and the refractive index besides their coating thickness. Aden and Kerker theory has been used to simulate the WGMs. The effect of refractive index of the medium and the microsphere on WGMs has been studied. Variations are observed in the decay rates of the excited state with the size of the microspheres on varying the refractive index of the medium surrounding the microcavity. It is found that (i) the observed quality factors (Q-values) are smaller by several orders of magnitude than those expected theoretically and (ii) the radiative rates are enhanced for Q-values > 3 × 103

Characteristic parameters of photonic nanojets of single dielectric microspheres illuminated by focused broadband radiation

Herein, we report the theoretical investigation on the photonic nanojets (PNJs) of single dielectric microspheres illuminated by focused broadband radiation (polychromatic light) from a Halogen lamp, supercontinuum source, light-emitting diode, and Hg arc lamp. The role of incident beam waist, refractive index of the surrounding medium, and radius of the microsphere on the characteristic parameters such as the electric field intensity enhancement, effective width, and length of the PNJ is studied. Interestingly, the characteristic parameters of the PNJs of solid microspheres obtained for the above-mentioned broadband radiation sources are found close to those observed for the focused monochromatic radiation of wavelengths which are near to the central wavelengths of the sources. Moreover, the characteristic parameters of PNJs of the core-shell microspheres of different thicknesses (t) illuminated by polychromatic radiation from most commonly used sources such as Halogen and Hg arc lamps are studied. For each t value, a suitable wavelength of monochromatic radiation has been found to generate the PNJ with characteristic parameters which are close to those obtained in the case of polychromatic radiation. We believe that the analytical theory and the theoretical simulations reported here would be useful for researchers who work in the fields such as PNJ assisted photoacoustic spectroscopy, white light nanoscopy, low-coherence phase-shifting interference microscopy, and Mirau interferometry.Published versio

The influence of metal nanoparticles on whispering gallery modes of a microcavity

Photonic microcavities offer high energy density and low mode volume and attract special attention due to wide range of applications. Subsequent developments in the area of plasmonic nanocavities have also opened up applications despite their high absorptive properties. In the last two decades, photonic-plasmonic hybrid microcavities have been investigated extensively. In this article, we have conducted a review of the literature on photonic and plasmonic systems individually as well as in hybrid systems. Along with the underlying physics, applications such as cavity quantum electrodynamics, lasing, sensing, nonlinear optics and Raman spectroscopy have been reviewed. The outputs of the systems for each applications have been discussed and compared for photonic and hybrid systems. This review will provide a thorough understanding of the effects of optical cavities and plasmonics and their applications