Summary Recent advances in visual sensing technology and unmanned aerial vehicle (UAV) provide an effective tool to capture the as‐is conditions of infrastructure and thus have gained their popularity in infrastructure inspection and documentation. To facilitate this process, several recent studies have proposed automated methods for detecting concrete cracks from UAV‐based images. This study is aimed at proposing a new method for automating both the detection and quantification of concrete cracks. The proposed method advances state‐of‐the‐art image‐based concrete crack detection methods by integrating the RGB images with the lidar data collected by UAV. The key innovations focus on two aspects: (1) by recognizing objects of interest in the lidar data, regions of interest can be extracted automatically from the images; (2) by retrieving the depth information through the lidar data, the actual pixel sizes can be estimated to facilitate both the detection and quantification of concrete cracks. In order to validate the proposed method, a customized UAV platform that was equipped with a high‐resolution camera and a Velodyne VLP‐16 lidar scanner was developed to scan the substructure elements of an in‐service bridge where multiple concrete cracks can be observed. The effectiveness of the proposed method in recognizing and quantifying concrete cracks is validated quantitively against manually annotated images and physical measurements. The results indicate that the proposed approach can recognize crack pixels with an accuracy of 85% on average as well as quantify the recognized concrete cracks with an error less than 10%.

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Highly flexible electromagnetic interference (EMI) shielding material with excellent shielding performance is of great significance to practical applications in nextgeneration flexible devices. However, most EMI materials suffer from insufficient flexibility and complicated preparation methods. In this study, we propose a new scheme to fabricate a magnetic Ni particle/Ag matrix composite ultrathin film on a paper surface. For a ~2 µm thick film on paper, the EMI shielding effectiveness (SE) was found to be 46.2 dB at 8.1 GHz after bending 200,000 times over a radius of ~2 mm. The sheet resistance (R□) remained lower than 2.30 Ω after bending 200,000 times.Contrary to the change in R□, the EMI SE of the film generally increased as the weight ratio of Ag to Ni increased, in accordance with the principle that EMI SE is positively related with an increase in electrical conductivity. Desirable EMI shielding ability, 2 ultrahigh flexibility, and simple processing provide this material with excellent application prospects.

Stretchable electronics, including bioelectronics, electronic skins, and artificial intelligence devices have attracted widespread attention. Stretchable nanocomposites have generated a great deal of interest from scientists because of their tunable properties. In this paper, stretching-induced conductive-dielectric transformations in nanocomposites are proposed and demonstrated for the first time. The transformations have been made possible with the use of four types of nanocomposites. For nanocomposites composed of polydimethylsiloxane (PDMS) and multiwalled carbon nanotubes (MWNTs, diameters 8−15 nm), the critical weight fraction of MWNTs in the transformation is 8.03%, and the specific tensile strain at the transformation point is 37%. When the applied tensile strain reaches the transformation point, the conductive nanocomposites transform into dielectrics. It has been speculated that electron hopping and tunnel currents become obstructed, and, hence, transformations are triggered. One application of this phenomenon is integrated resistive-capacitive strain sensors, which show potential in e-skin applications. A reusable e-skin switch was tested at a person's knuckle. The performance of the fabricated switch exhibited reversibility and repeatability of the conductive-dielectric transformations. The critical transformation weight fractions and transformation points of the three other nanocomposites were also found, but the matrix was replaced with Eco-flex, and the conductive carriers were silver nanoparticles and carboxyl MWNTs.