Recent progress in aircraft smart skin for structural health monitoring

Through the integration of advanced sensors, actuators, and micro-processors, aircraft smart skin technology can improve the structural performance of aircraft and make them self-perception, self-diagnosis, self-adaptation, self-learning, and self-repair. Aircraft smart skin for structural health monitoring (SHM) is an important type of aircraft smart skin and has received extensive attention in recent years. Large-scale, lightweight, and low-power consumption are three key problems hindering the realization and engineering applications of aircraft smart skin for SHM. In view of these problems and restrictions of practical aircraft onboard applications, this article reviews the current research progress on aircraft smart skin for SHM, introduces their design, materials, manufacturing process, and monitoring principles in detail, and discusses how they study above problems from these aspects. Finally, perspectives are proposed on the opportunities and future developments of aircraft smart skin for SHM.

Active Flutter Suppression of Smart-Skin Antenna Structures with Piezoelectric Sensors and Actuators

A smart-skin antenna structure is investigated for active flutter control with piezoelectric sensors and actuators. The skin antenna is designed as a multilayer sandwich structure with a dielectric polymer to perform the role of antenna or radar structures. The governing equations are developed according to the first-order shear deformation theory, and von Karman strain–displacement relationships are used for the moderate geometrical nonlinearity. To consider the supersonic airflow, first-order piston theory is performed for the aerodynamic pressures. The linear quadratic regulator (LQR) method is applied as a control algorithm, and Newmark’s method is studied to obtain the numerical results. In the present study, the effects of placements and shape of piezoelectric patches are discussed on the flutter control of the model in detail. In addition, the numerical results show that the skin antenna model can effectively suppress the panel flutter behaviors of the model, optimal conditions of piezoelectric patches are obtained for skin antenna structures.

Diving beetle–like miniaturized plungers with reversible, rapid biofluid capturing for machine learning–based care of skin disease

Recent advances in bioinspired nano/microstructures have received attention as promising approaches with which to implement smart skin-interfacial devices for personalized health care. In situ skin diagnosis requires adaptable skin adherence and rapid capture of clinical biofluids. Here, we report a simple, all-in-one device consisting of microplungers and hydrogels that can rapidly capture biofluids and conformally attach to skin for stable, real-time monitoring of health. Inspired by the male diving beetle, the microplungers achieve repeatable, enhanced, and multidirectional adhesion to human skin in dry/wet environments, revealing the role of the cavities in these architectures. The hydrogels within the microplungers instantaneously absorb liquids from the epidermis for enhanced adhesiveness and reversibly change color for visual indication of skin pH levels. To realize advanced biomedical technologies for the diagnosis and treatment of skin, our suction-mediated device is integrated with a machine learning framework for accurate and automated colorimetric analysis of pH levels.