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( E )-4-Fluoro-cinnamaldehyde malononitrile (( E )- 4FCM ) is a new phenylbutadiene derivative that undergoes a [2+2] photocycloaddition in the crystal form. Optical absorption and proton nuclear magnetic resonance ( 1 H-NMR) measurements demonstrate that the solid-state ( E )- 4FCM photodimerization is a negative photochromic reaction that proceeds to 97% completion. The large geometry change and full conversion allow bulk crystals of ( E )- 4FCM to show strong photosalient effects when exposed to 405 nm ultraviolet light. When ( E )- 4FCM nanowires are grown in an anodic alumina oxide (AAO) template, they maintain a high degree of crystallinity and orientation, as determined by X-ray diffraction measurements. When illuminated, ( E )- 4FCM nanowire bundles exhibit a rapid expansion, during which they spread by as much as 300% in the lateral direction. This lateral expansion is at least partially due to a photoinduced crystal expansion along the diameter of the nanowires. When ( E )- 4FCM nanowires are confined inside the AAO template, the photoinduced expansion can be harnessed to deform the template, causing it to bend under UV light irradiation. The bending motion due to 2.0 mg of 4FCM in a template can cause the template to bend by up to 1.0 mm and lift up to 200 g. These results represent a significant improvement in work output relative to previous composite actuator membranes based on diarylethene photochromes. 

Abstract Detection of long wave infrared (LWIR) light at room temperature is a long‐standing challenge due to the low energy of photons. A low‐cost, high‐performance LWIR detector or camera that operates under such conditions is pursued for decades. Currently, all available detectors operate based on amplitude modulation (AM) and are limited in performance by AM noises, including Johnson noise, shot noise, and background fluctuation noise. To address this challenge, a frequency modulation (FM)‐based detection technique is introduced, which offers inherent robustness against different types of AM noises. The FM‐based approach yields an outstanding room temperature noise equivalent power (NEP), response time, and detectivity (D*). This result promises a novel uncooled LWIR detection scheme that is highly sensitive, low‐cost, and can be easily integrated with electronic readout circuitry, without the need for complex hybridization. 

Abstract Nanostructured materials have enabled new ways of controlling the light–matter interaction, opening new routes for exciting applications, in display technologies and colorimetric sensing, among others. In particular, metallic nanoparticles permit the production of color structures out of colorless materials. These plasmonic structural colors are sensitive to the environment and thus offer an interesting platform for sensing. Here, a self‐assembly of aluminum nanoparticles in close proximity of a mirror is spaced by an ultrathin poly(N‐isopropylacrylamide) (PNIPAM) layer. Hybridizing the plasmonic system with the active polymer layer, a thermoresponsive gap‐plasmon architecture is formed that transduces changes in the temperature and relative humidity of the environment into color changes. By harnessing the environmentally induced structural changes of PNIPAM, it was estimated from the finite difference time domain simulation that the resonance can be tuned 7 nm per every 1 nm change in thickness, resulting in color variation. Importantly, these fully reversible changes can be used for reusable powerless humidity and temperature colorimetric sensing. Crucially if condensation on the structure happens, the polymer layer is deformed beyond recovery and the colors are washed away. We leverage this effect to produce tamper‐proof dew labels that a straightforward smartphone app can read by taking a picture.