High-Precision Wearable Displacement Sensing System for Clinical Diagnosis of Anterior Cruciate Ligament Tears.

An anterior cruciate ligament (ACL) tear is a common musculoskeletal injury with a high incidence. Traditional diagnosis employs magnetic response imaging (MRI), physical testing, or other clinical examination, which relies on complex and expensive medical instruments, or individual doctoral experience. Herein, we propose a wearable displacement sensing system based on a grating-structured triboelectric stretch sensor to diagnose the ACL injuries. The stretch sensor exhibits a high resolution (0.2 mm) and outstanding robustness (over 1,000,000 continuous operation cycles). This system is employed in clinical trial to diagnose ACL injuries. It measures the displacement difference between the affected leg and the healthy leg during Lachman test. And when such a difference is greater than 3 mm, the ACL is considered to be at risk for injury or tear. Compared with the gold standard of arthroscopy, the consistency rate of this wearable diagnostic system reached about 85.7%, which is higher than that of the Kneelax3 arthrometer (78.6%) with a large volume. This shows that the wearable system possesses the feasibility to supplement and improve existing arthrometers for facile diagnosing ACL injuries. It may take a promising step for wearable healthcare.

Multifunctional Nanogenerator-Integrated Metamaterial Concrete Systems for Smart Civil Infrastructure.

Creating multifunctional concrete materials with advanced functionalities and mechanical tunability is a critical step toward reimagining the traditional civil infrastructure systems. Here, the concept of nanogenerator-integrated mechanical metamaterial concrete is presented to design lightweight and mechanically tunable concrete systems with energy harvesting and sensing functionalities. The proposed metamaterial concrete systems are created via integrating the mechanical metamaterial and nano-energy-harvesting paradigms. These advanced materials are composed of reinforcement auxetic polymer lattices with snap-through buckling behavior fully embedded inside a conductive cement matrix. We rationally design their composite structures to induce contact-electrification between the layers under mechanical excitations/triggering. The conductive cement enhanced with graphite powder serves as the electrode in the proposed systems, while providing the desired mechanical performance. Experimental studies are conducted to investigate the mechanical and electrical properties of the designed prototypes. The metamaterial concrete systems are tuned to achieve up to 15% compressibility under cycling loading. The power output of the nanogenerator-integrated metamaterial concrete prototypes reaches 330 µW. Furthermore, the self-powered sensing functionality of the nanogenerator concrete systems for distributed health monitoring of large-scale concrete structures is demonstrated. The metamaterial concrete paradigm can possibly enable the design of smart civil infrastructure systems with a broad range of advanced functionalities.

Flexible Wood-Based Triboelectric Self-Powered Smart Home System.

With the rapid development of the Internet of Things, artificial intelligence, and big data, the smart home has played a critical role in human life and smart cities, where large amounts of distributed sensors should be applied. Here, we report a natural wood-based triboelectric self-powered sensor (WTSS) for building the smart home system. Based on an effective and simple treatment strategy for natural wood, the WTSS shows superior sensitivity, flexibility, stability, and thinness. Owing to the extensive use of wood materials in home construction, the WTSS is integrated with household facilities and applied in three real-time human-machine interfaces, including a smart home control system, a smart password gate control system, and a smart floor monitoring system, with advantages of low cost, easy operation, and eco-friendliness. This work promotes the development of wood-based flexible electronics and shows potential applications in the construction of smart homes and future cities.

Rehabilitation of Total Knee Arthroplasty by Integrating Conjoint Isometric Myodynamia and Real-Time Rotation Sensing System.

As the world population structure has already exhibited an inevitable trend of aging, technical advances that can provide better eldercare are highly desired. Knee osteoarthritis, one of the most common age-associated diseases, can be effectively treated via total knee arthroplasty (TKA). However, patients are suffering from the recovery process due to inconvenience in post-hospital treatment. Here, a portable, modular, and wearable brace for self-assessment of TKA patients' rehabilitation is reported. This system mainly consists of a force transducer for isometric muscle strength measurement and an active angle sensor for knee bending detection. Clinical experiments on TKA patients demonstrate the feasibility and significance of the system. Specifically, via brace-based personalized healthcare, the TKA patients' rehabilitation process is quantified in terms of myodynamia, and a definite rehabilitation enhancement is obtained. Additionally, new indicators, that is, isometric muscle test score, for evaluating TKA rehabilitation are proposed. It is anticipated that, as the cloud database is employed and more rehabilitation data are collected in the near future, the brace system can not only facilitate rehabilitations of TKA patients, but also improve life quality for geriatric patients and open a new space for remote artificial intelligence medical engineering.

Active-Sensing Epidermal Stretchable Bioelectronic Patch for Noninvasive, Conformal, and Wireless Tendon Monitoring.

Sensors capable of monitoring dynamic mechanics of tendons throughout a body in real time could bring systematic information about a human body's physical condition, which is beneficial for avoiding muscle injury, checking hereditary muscle atrophy, and so on. However, the development of such sensors has been hindered by the requirement of superior portability, high resolution, and superb conformability. Here, we present a wearable and stretchable bioelectronic patch for detecting tendon activities. It is made up of a piezoelectric material, systematically optimized from architectures and mechanics, and exhibits a high resolution of 5.8 × 10-5 N with a linearity parameter of R 2 = 0.999. Additionally, a tendon real-time monitoring and healthcare system is established by integrating the patch with a micro controller unit (MCU), which is able to process collected data and deliver feedback for exercise evaluation. Specifically, through the patch on the ankle, we measured the maximum force on the Achilles tendon during jumping which is about 16312 N, which is much higher than that during normal walking (3208 N) and running (5909 N). This work not only provides a strategy for facile monitoring of the variation of the tendon throughout the body but also throws light on the profound comprehension of human activities.