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Intrinsically stretchable light-emitting diodes (LEDs) are demonstrated using organometal-halide-perovskite/polymer composite emitters. The polymer matrix serves as a microscale elastic connector for the rigid and brittle perovskite and induces stretchability to the composite emissive layers. The stretchable LEDs consist of poly(ethylene oxide)-modified poly(3,4-ethylenedioxythiophene) polystyrene sulfonate as a transparent and stretchable anode, a perovskite/polymer composite emissive layer, and eutectic indium-gallium as the cathode. The devices exhibit a turn-on voltage of 2.4 V, and a maximum luminance intensity of 15 960 cd m at 8.5 V. Such performance far exceeds all reported intrinsically stretchable LEDs based on electroluminescent polymers. The stretchable perovskite LEDs are mechanically robust and can be reversibly stretched up to 40% strain for 100 cycles without failure.

It is highly desirable for liquid crystal elastomer (LCE) based microactuators to activate and actuate in a highly controlled fashion without perturbing the surrounding environment. To reach this goal, in this study, a novel experimental protocol is developed to successfully incorporate gold nanosphere (AuNS) and gold nanorod (AuNR) into polyacrylate based LCE elastomer to fabricate LCE/AuNR and LCE/AuNS micropillars or microactuators. The effect of gold nanoparticle inclusion has been studied by spectroscopy (UVvis-near-infrared), microscopy (transmission electron microscopy), thermal analysis (differential scanning calorimetry and thermogravimetric analysis), and x-ray scattering (wide-angle x-ray scattering and small-angle x-ray scattering). Finite element analysis is performed to examine the feasibility of utilizing the photothermal effect of AuNR/AuNS to enable photothermal actuation of LCE/AuNR and LCE/AuNS micropillars. The comparative experimental studies on the thermal and photothermal actuation behavior of the LCE, LCE/AuNS, and LCE/AuNR micropillar suggested that AuNR is an excellent candidate for developing high-performance LCE actuators with photothermal actuation capability. With inclusion of less than 1 wt% of AuNR, the very high maximum actuation strain (30%) and rapid response (a few seconds) have been achieved in LCE/AuNR micropillar actuators under 635 nm laser irradiation.

We report highly sensitive and reliable strain sensors based on silver nanoparticle (AgNP) and carbon nanotube (CNT) composite thin films. The CNT/AgNP was prepared by a screen printing process using a mixture of a CNT paste and an AgNP ink. It is discovered that the sensitivity of such sensors are highly dependent on the crack formation in the composites. By altering the substrate use and the relative ratios of AgNPs and CNTs, the formation and propagation of cracks can be properly engineered, leading to piezoresistive strain sensors with enhanced sensitivity and robustness.Electronic supplementary materialThe online version of this article (doi:10.1186/s11671-016-1626-z) contains supplementary material, which is available to authorized users.

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Capability to detect or track macrophages in vivo is important for developing macrophage-based therapies. Dispersed carbon nanotubes (CNTs) have been used for Raman labeling of cells and a topdown approach has been developed to fabricate disk-shaped microparticles for the same application. This study presents the first fabrication of disk-shaped microparticles termed microdevices containing densely packed CNTs and Raman labeling of macrophages with the microdevices. The fabrication is featured by the use of spray coating of CNTs to produce the microdevices. Raman detection of a single microdevice at a centimeter-scale working distance and the feasibility of using chemically modified CNTs for multiplexed Raman labeling were demonstrated. Macrophages were stably labeled with the microdevices by simply adding the microdevices to cultivated macrophages. The labeling slightly reduced viability of the macrophages and the labeled macrophages retained their ability to capture foreign particles. Moreover, Raman detection of a single macrophage was demonstrated. The microdevices promise to be useful for detection or tracking of macrophages in vivo as well as for other biomedical applications.

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