Search

Strain sensors that can rapidly and efficiently detect strain distribution and magnitude are crucial for structural health monitoring and human–computer interactions. However, traditional electrical and optical strain sensors make access to structural health information challenging because data conversion is required, and they have intricate, delicate designs. Drawing inspiration from the moisture-responsive coloration of beetle wing sheaths, we propose using Ecoflex as a flexible substrate. This substrate is coated with a Fabry–Perot (F–P) optical structure, comprising a "reflective layer/stretchable interference cavity/reflective layer", creating a dynamic color-changing visual strain sensor. Upon the application of external stress, the flexible interference chamber of the sensor stretches and contracts, prompting a blue-shift in the structural reflection curve and displaying varying colors that correlate with the applied strain. The innovative flexible sensor can be attached to complex-shaped components, enabling the visual detection of structural integrity. This biomimetic visual strain sensor holds significant promise for real-time structural health monitoring applications. [ABSTRACT FROM AUTHOR]

Organic photodiodes (OPDs) have recently garnered attention as a competitive alternative to their inorganic counterparts, given their inherent advantages in solution processability, mechanical flexibility, and cost‐effective manufacturing. In this work, a novel method for fabricating high‐performance semitransparent color OPDs by integrating Fabry–Perot (FP) interferometer‐based color‐filtering electrodes and solution‐processed distributed Bragg reflectors (sDBRs) is introduced. The FP electrode provides color control by modulating the metal oxide layer thickness, irrespective of the photoactive layer's color. To overcome limitations related to light absorption and device transparency, this work employs a sDBR as a selective window reflector, allowing the OPD to retain its color while preserving semitransparency. The experimental findings demonstrate the successful integration of these components, resulting in semitransparent red, green, and blue (RGB) OPDs exhibiting significantly improved detectivity. The fabricated RGB‐OPDs achieve detectivity values of 4.07, 3.49, and 4.22 × 1010 cm Hz1/2 W−1 for red, green, and blue, respectively. This research highlights the efficacy of FP and sDBR color filters in realizing high‐performance color sensors and offer novel opportunities for semitransparent OPD integration with other optoelectronic devices. [ABSTRACT FROM AUTHOR]

Strain sensors that can rapidly and efficiently detect strain distribution and magnitude are crucial for structural health monitoring and human–computer interactions. However, traditional electrical and optical strain sensors make access to structural health information challenging because data conversion is required, and they have intricate, delicate designs. Drawing inspiration from the moisture-responsive coloration of beetle wing sheaths, we propose using Ecoflex as a flexible substrate. This substrate is coated with a Fabry–Perot (F–P) optical structure, comprising a “reflective layer/stretchable interference cavity/reflective layer”, creating a dynamic color-changing visual strain sensor. Upon the application of external stress, the flexible interference chamber of the sensor stretches and contracts, prompting a blue-shift in the structural reflection curve and displaying varying colors that correlate with the applied strain. The innovative flexible sensor can be attached to complex-shaped components, enabling the visual detection of structural integrity. This biomimetic visual strain sensor holds significant promise for real-time structural health monitoring applications.

Abstract Organic photodiodes (OPDs) have recently garnered attention as a competitive alternative to their inorganic counterparts, given their inherent advantages in solution processability, mechanical flexibility, and cost‐effective manufacturing. In this work, a novel method for fabricating high‐performance semitransparent color OPDs by integrating Fabry–Perot (FP) interferometer‐based color‐filtering electrodes and solution‐processed distributed Bragg reflectors (sDBRs) is introduced. The FP electrode provides color control by modulating the metal oxide layer thickness, irrespective of the photoactive layer's color. To overcome limitations related to light absorption and device transparency, this work employs a sDBR as a selective window reflector, allowing the OPD to retain its color while preserving semitransparency. The experimental findings demonstrate the successful integration of these components, resulting in semitransparent red, green, and blue (RGB) OPDs exhibiting significantly improved detectivity. The fabricated RGB‐OPDs achieve detectivity values of 4.07, 3.49, and 4.22 × 1010 cm Hz1/2 W−1 for red, green, and blue, respectively. This research highlights the efficacy of FP and sDBR color filters in realizing high‐performance color sensors and offer novel opportunities for semitransparent OPD integration with other optoelectronic devices.

Traditional Fabry–Perot (F–P) structures comprising "metal/interference medium/phase-change material (PCM)" (MIP) nanostructures have achieved a color gamut close to the standard RGB (sRGB) space. However, the narrow absorption band in the visible region hinders further improvement in the gamut. Nonetheless, a large gamut is critical for display and imaging devices. This paper proposes a reflector nanostructure consisting of "metal/interference medium/phase-change materials (PCMs)/interference medium" (MIPI) to regulate the optical reflection in the visible waveband. We performed simulations to demonstrate that the addition of a 100–250-nm-thick interference medium causes the structure to change from a single to compound interference effect, thus significantly expanding the gamut (51% larger than that of the traditional MIP structure). The influences of the structure geometry and phase changes of the PCM layer on the spectral regulation were analyzed by combining experimental and simulation methods. The results indicate that the proposed structure covers almost the entire sRGB gamut. Moreover, adding the second interference medium induces a longer optical path of the incident light, which renders the structure color-sensitive to the observation angle, thus allowing for the demonstration of an anti-counterfeiting application. This nanoscale MIPI design can serve as a basis for the realization of color-regulation devices and encryption applications. [ABSTRACT FROM AUTHOR]

Structural color technology has garnered extensive attention in the development of ink-free color technology for applications such as color displays, color reflectors, and colorimetric devices. A Fabryâ€"Perot (Fâ€"P) structure formed by stacking a metal base, an interference cavity, and a phase change material layer (MIP) is of significant interest as a lithography-free and scalable color-reflecting structure. Such a structure can selectively reflect interfered light over a range of visible wavelengths, resulting in bright colors. However, obtaining a wide range of saturation regulation spaces has become a challenge. In this study, an Fâ€"P color reflector based on a phase-change material (PCM) base is proposed, which consists of a PCM base, an interference layer, and a PCM top layer (PIP). The results of the finite element simulation and experimental measurements demonstrated that the PIP reflector had an adjustable saturation range 10.75 times larger than that of the MIP reflector. The effects of the structure size and phase change of the PCM layer on the structural characteristics were further analyzed. In addition, the performance of laser-induced color change and its application in color printing were demonstrated. The present study sheds new light on color reflectors, and the strategy proposed indicates their potential optoelectronic applications based on saturation modulation. [ABSTRACT FROM AUTHOR]

Detecting the chirality of material is very important in material science, chemistry, pharmacology, and biomaterial science because it is useful for identifying and discarding unintended side effects. Here, directly visualized is the optical activity of chiral samples using an orientation‐controlled helical nanofilament (HNF, B4) liquid crystal (LC) phase made of achiral bent‐shaped molecules. The vertical orientation of the HNFs is induced by shining unpolarized UV light. Right‐ or left‐handed domains of the HNFs are formed because of the lack of molecular chirality, each single‐handed domain is large enough to be seen with the naked eye, up to ≈several mm2. The periodic arrays of aligned HNFs reflect a specific color, here green, due to the Bragg reflection. Such a reflector enables an easy detection of optical activity of a sample placed on it. The device is tested with naturally chiral substances, like fructose and glucose, which exhibit opposite sense of optical activity, as well as with structurally chiral nematic LC phase and reveals high sensitivity of a detection. [ABSTRACT FROM AUTHOR]