Structural colors traditionally refer to colors arising from the interaction of light with structures with periodicities on the order of the wavelength. Recently, the definition has been broadened ...

Nanophotonic Structural Colors

Thermoelectric energy harvesting is one of the keystones of modern green renewable energy generation. Unfortunately, most conventional state-of-the-art inorganic semiconductor thermoelectric generators are expensive, fragile, and not flexible. Considering these limitations, we developed a flexible printable thermoelectric generator (TEG) with both n-type and p-type organic composites of reduced graphene oxide, carbon nanotubes, poly(3,4-ethylenedixoythiphene)–polystyrene sulfate, and lead sulfide composite materials. We constructed a TEG of ten alternating n–p pairs as a prototype with an effective area of 1.4 cm2 each, which generated 13 mV thermovoltage at operating temperature difference of 77 °C. It demonstrates that its fabrication is scalable, printable, and relatively simple, and the resultant structure is flexible, conformal, and reconfigurable.

A flexible, printable, thin-film thermoelectric generator based on reduced graphene oxide–carbon nanotubes composites

Herein we determine the Seebeck coefficients, electric conductivities, and thermoelectric power factors of a range of unreduced graphene oxide (GO)/single-wall carbon nanotube (CNT) membranes incorporating different GO/CNT ratios as well as of a series of reduced graphene oxide (rGO) membranes for which reduction had occurred at different temperatures. The considerable thermoelectric power factor of 5.33 × 10−2 μW mK−2 generated from unreduced GO/CNT (1 : 2 ratio) is in agreement with its suitability for application as a flexible thermoelectric material. Moreover, compared to the conventional architectures of traditional thermoelectric materials, the inherent flexibility of GO-based thermoelectric materials opens the door to improved performance and efficiency, with lightweight, scalable, stretchable, and/or wearable materials being the outcome.

/pdf/enhanced-thermoelectric-properties-exhibited-by-unreduced-1r0ffo8szn.pdf

Enhanced thermoelectric properties exhibited by unreduced freestanding graphene oxide/carbon nanotube membranes

Chemical detection of vapour-phase analytes is increasingly moving toward deployment of low size, weight and power (SWaP) instruments. Each measurement technique has its strengths and shortcomings. Advanced colourimetry can provide and fill a needed role in this mission space. In this review, an overview of the methods for colourimetric detection of analyte vapours is provided in the context of both qualitative and quantitative determination. A parametric analysis of the colourimetric sensor design is presented to help inform the design of highly sensitive colourimetric sensors for analyte quantification. Included is a discussion on factors leading to deviations from ideal sensor performance. This review also identifies extensions in the use space for colourimetry as well as key challenges in further sensor development.

Colourimetry for the sensitive detection of vapour-phase chemicals: State of the art and future trends

The threat of exposure to toxic chemicals is of great concern. In order to provide a chemical situational awareness, we are developing a new type of chemical sensor based on a novel fabric spectrometer-based colorimetric chemical sensor that is low size, weight, and power (SWaP). We are exploring the key design principles for photonic transducers to enable a new approach to chemical threat sensing. The fabric spectrometer is based on a functional fiber platform in which the semiconductor-containing fiber is miniature in two dimensions and extendable in the third dimension (along the fiber length). By exploring fibers, and films that can be scaled to a fiber geometry, we will enable a new fiber-based chemical threat detector that can serve in textiles as well as other interesting form factors.

Chemical sensing via a low SWaP wearable spectrometer

https://iopscience.iop.org/article/10.1088/2053-1591/ab18d7/pdf

A microstructuring route to enhanced thermoelectric efficiency of reduced graphene oxide films

Chemical warfare agents (CWAs) such as nerve and blister agents are expected to pose continuing and growing dangers for the Warfighter in the future. We investigate a novel chemical detection modality, based on a new platform for colorimetric detection of chemical threats incorporated in hollow fibers, which are miniature in two dimensions and extendable (“extrudable”) in the third dimension (along the fiber length). By exploring fibers, and films that can be scaled to a fiber geometry, we will enable a new fiber-based chemical threat detector that can serve in textiles worn by the Warfighter (e.g., uniform), as well as in non-worn textiles and an outlying fence or perimeter for early detection of a threat cloud near an expeditionary shelter, outpost, encampment, or base.

Fiber-based chemical sensing and sensing platforms with colorimetric dyes

Surface plasmon polaritons (SPPs) are traditionally excited by plane waves within the Rayleigh range of a focused transverse-magnetic (TM) Gaussian beam. Here we investigate and confirm the coupling between SPPs and two-dimensional Gaussian and Bessel-Gauss wave packets, as well as one-dimensional light sheets and space-time wave packets. We encode the incoming wavefronts with spatially varying states of polarization; then we couple the respective TM components of radial and azimuthal vector beam profiles to confirm polarization-correlation and spatial-mode selectivity. Our results do not require material optimization or multi-dimensional confinement via periodically corrugated metal surfaces to achieve coupling at a greater extent, hereby outlining a pivotal, yet commonly overlooked, path towards the development of long-range biosensors and all-optical integrated plasmonic circuits.

Excitation of surface plasmon polaritons by diffraction-free and vector beams.

Surface plasmon polaritons (SPPs) are traditionally excited by plane waves within the Rayleigh range of a focused transverse magnetic (TM) Gaussian beam. Here, we investigate and confirm the coupling between SPPs and two-dimensional Gaussian and Bessel-Gauss wave packets, as well as one-dimensional light sheets and space-time wave packets. We encode the incoming wavefronts with spatially varying states of polarization then couple the respective TM components of radial and azimuthal vector beam profiles to confirm SPP polarization-correlation and spatial-mode selectivity. Our results do not require material optimization or multi-dimensional confinement via periodically corrugated metal surfaces to achieve coupling at greater extents. Hereby, outlining a pivotal, yet commonly overlooked, path towards the development of long-range biosensors and all-optical integrated plasmonic circuits. 

/pdf/excitation-of-surface-plasmon-polaritons-by-diffraction-free-1fuomwyj.pdf

Rachel Odessey

Papers

A microstructuring route to enhanced thermoelectric efficiency of reduced graphene oxide films

Fiber-based chemical sensing and sensing platforms with colorimetric dyes

Excitation of surface plasmon polaritons by diffraction-free and vector beams.

Excitation of surface plasmon polaritons by diffraction-free and vector beams

Reduced angle sensitivity of structural coloration on an industrial aluminium platform