Plastic scintillators have been investigated for γ-ray detection with the promise of fast response, ease of scale up, and mechanical toughness. However, their low light yield has been a major limiting factor in the performance metrics. Herein, we report a cross-linkable fluorene derivative, 9,9-bis­(4-vinylbenzyl)-9H-fluorene (SF), copolymerized with the plastic matrix, to facilitate effective Förster resonance energy transfer to boost the light yield. Noncurable 9,9-dimethyl-9H-fluorene (MF) and 9,9′-spirobifluorene (SBF) were also introduced to bridge the energy transfer gap between the polymer matrix and the primary dye. The plastic scintillator comprising 5 wt % SF and 20 wt % MF exhibits a light yield of 11 600 photons/MeV with a scintillation decay time constant of 2.3 ns.

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Cesium lead bromide quantum dot (CsPbBr3 QD) is emerging as a promising luminescent material for gamma ray detection. However, its intensive self-absorption traps the luminescent photons generated and diminishes the scintillation light yield. The self-absorption is magnified at high CsPbBr3 QD loading and large scintillator volume, which are required to effectively attenuate gamma photons. We report a liquid scintillator loaded with up to 40 wt % of CsPbBr3 QDs. Pyrromethene 580 (PM-580), a fluorescent dye, was co-dissolved in the solution as a fluorescence resonance energy-transfer acceptor to overcome the self-absorption of the QDs. The rapid energy transfer from the QDs to PM-580 also accelerates the scintillation decay kinetics. The scintillation light yield of the liquid containing 20 wt % QDs and 0.75 wt % PM-580 was 8800 photons/MeV. The decay lifetime is 24.3 ns, faster than most inorganic crystal scintillators. The light yield was 7300 photons/MeV at 40 wt % QD loading. Gamma pulse spectroscopy of the 40 wt % QD liquid produced the 662 keV gamma photopeak with a 27% energy resolution, demonstrating the potential of the CsPbBr3 QD loaded organic scintillators for spectroscopic gamma detection.

Conventional robotic systems are built with rigid materials to deal with large forces and predetermined processes. Soft robotics, however, is an emerging field seeking to develop adaptable robots that can perform tasks in unpredictable environments and biocompatible devices that close the gap between humans and machines. Dielectric elastomers (DEs) have emerged as a soft actuation technology that imitates the properties and performance of natural muscles, making them an attractive material choice for soft robotics. However, conventional DE materials suffer from electromechanical instability (EMI), which reduces their performance and limits their applications in soft robotics. This review discusses key innovations in DE artificial muscles from a material standpoint, followed by a survey on their representative demonstrations of soft robotics. Specifically, we introduce modifications of DE materials that enable large strains, fast responses, and high energy densities by suppressing EMI. Additionally, we examine materials that allow variable stiffness and self‐healing abilities in DE actuators. Finally, we review dielectric elastomer actuator (DEA) applications in soft robotics in four categories, including automation, manipulation, locomotion, and human interaction.

Dielectric elastomer generators (DEGs) can convert mechanical energy into electricity based on variable capacitance. DEGs can potentially harvest energy from renewable energy source such as wind and ocean waves due to their light weight, low cost, and high energy density. To scale up the energy output, multiple single-layer generator units are stacked to form a multilayer DEG. The fabrication of DEGs with reliable multilayer structure having high deformability and long-term stability remains a critical challenge. We report a scalable multilayering technique to produce robust DEG stacks with circular diaphragm configuration. A 4-layer stacked VHB films showed a threefold voltage gain during constant charge operation and an estimated energy density of 100 J/kg. Furthermore, by introducing a dielectric elastomer binder between the VHB films, we demonstrate strong interlayer adhesion in the stacked DEGs, enabling long-term operation stability. As a result, a 4-layer circular diaphragm DEG survived more than 100,000 cycles of mechanical deformation between 0 and 100% area strain. Carbon nanotube (CNT) coating was used as the compliant electrode. Its resistance remains almost constant after 4000 cycles of conditioning.