Flexible High-Resolution Triboelectric Sensor Array Based on Patterned Laser-Induced Graphene for Self-Powered Real-Time Tactile Sensing

Flexible tactile sensors are garnering substantial interest for various promising applications, including artificial intelligence, prosthetics, healthcare monitoring, and human–machine interactions (HMI). However, it still remains a critical challenge in developing high-resolution tactile sensors without involving high-cost and complicated manufacturing processes. Herein, a flexible high-resolution triboelectric sensing array (TSA) for self-powered real-time tactile sensing is developed through a facile, mask-free, high-efficient, and environmentally friendly laser direct writing technique. A 16 × 16 pixelated TSA with a resolution of 8 dpi based on patterned laser-induced graphene (LIG) electrodes (7 Ω sq⁻¹) is fabricated by the complementary intersection overlapping between upper and lower aligned semicircular electrode arrays. With the especially patterning design, the complexity of TSA and the number of data channels is reduced. Meanwhile, the TSA platform exhibits excellent durability and synchronicity and enables the achievement of real-time visualization of multipoint touch, sliding, and tracking motion trajectory without power consumption. Furthermore, a smart wireless controlled HMI system, composed of a 9-digital arrayed touch panel based on a LIG-patterned triboelectric nanogenerator, is constructed to control personal electronics wirelessly. Consequently, the self-powered TSA as a promising platform demonstrates great potential for an active real-time tactile sensing system, wireless controlled HMI, security identification and, many others.     

Stretchable,Washable, and Ultrathin Triboelectric Nanogenerators as Skin-Like Highly Sensitive Self-Powered Haptic Sensors

Accompanying the boom in multifunctional wearable electronics, flexible, sustainable, and wearable power sources are facing great challenges. Here, a stretchable, washable, and ultrathin skin-inspired triboelectric nanogenerator (SI-TENG) to harvest human motion energy and act as a highly sensitive self-powered haptic sensor is reported. With the optimized material selections and structure design, the SI-TENG is bestowed with some merits, such as stretchability ( ≈ 800%), ultrathin ( ≈ 89 µ m), and light-weight ( ≈ 0.23 g), which conformally attach on human skin without disturbing its contact. A stretchable composite electrode, which is formed by homogenously intertwining silver nanowires (AgNWs) with thermoplastic polyurethane (TPU) nanofiber networks, is fabricated through synchronous electrospinning of TPU and electrospraying of AgNWs. Based on the triboelectrification effect, the open-circuit voltage, short-circuit current, and power density of the SI-TENG with a contact area of 2 × 2 cm² and an applied force of 8 N can reach 95 V, 0.3 µ A, and 6 mW m⁻², respectively. By integrating the signal-processing circuits, the SI-TENG with excellent energy harvesting and self-powered sensing capability is demonstrated as a haptic sensor array to detect human actions. The SI-TENG exhibits extensive applications in the fields of human–machine interface and security systems.     

Self‐Healing,Flexible, and Tailorable Triboelectric Nanogenerators for Self‐Powered Sensors based on Thermal Effect of Infrared Radiation

Self‐healing triboelectric nanogenerators (TENGs) with flexibility, robustness, and conformability are highly desirable for promising flexible and wearable devices, which can serve as a durable, stable, and renewable power supply, as well as a self‐powered sensor. Herein, an entirely self‐healing, flexible, and tailorable TENG is designed as a wearable sensor to monitor human motion, with infrared radiation from skin to promote self‐healing after being broken based on thermal effect of infrared radiation. Human skin is a natural infrared radiation emitter, providing favorable conditions for the device to function efficiently. The reversible imine bonds and quadruple hydrogen bonding (UPy) moieties are introduced into polymer networks to construct self‐healable electrification layer. UPy‐functionalized multiwalled carbon nanotubes are further incorporated into healable polymer to obtain conductive nanocomposite. Driven by the dynamic bonds, the designed and synthesized materials show excellent intrinsic self‐healing and shape‐tailorable features. Moreover, there is a robust interface bonding in the TENG devices due to the similar healable networks between electrification layer and electrode. The output electric performances of the self‐healable TENG devices can almost restore their original state when the damage of the devices occurs. This work presents a novel strategy for flexible devices, contributing to future sustainable energy and wearable electronics.     

Multifunctional and Wearable Patches Based on Flexible Piezoelectric Acoustics for Integrated Sensing,Localization, and Underwater Communication

Flexible and wearable sensors are highly desired for health monitoring, agriculture, sport, and indoor positioning systems applications. However, the currently developed wireless wearable sensors, which are communicated through radio signals, can only provide limited positioning accuracy and are often ineffective in underwater conditions. In this paper, a wireless platform based on flexible piezoelectric acoustics is developed with multiple functions of sensing, communication, and positioning. Under a high frequency (≈13 MHz) stimulation, Lamb waves are generated for respiratory monitoring. Whereas under low-frequency stimulation (≈20 kHz), this device is agitated as a vibrating membrane, which can be implemented for communication and positioning applications. Indoor communication is demonstrated within 2.8 m at 200 bps or 4.2 m at 25 bps. In combination with the sensing function, real-time respiratory monitoring and wireless communication are achieved simultaneously. The distance measurement is achieved based on the phase differences of transmitted and received acoustic signals within a range of 100 cm, with a maximum error of 3 cm. This study offers new insights into the communication and positioning applications using flexible acoustic wave devices, which are promising for wireless and wearable sensor networks.     

Self‐Powered Vehicle Emission Testing System Based on Coupling of Triboelectric and Chemoresistive Effects

Traditional triboelectric nanogenerator (TENG)‐based self‐powered chemical‐sensing systems are demonstrated by measuring the triboelectric effect of the sensing materials altered by the external stimulus. However, the limitations of triboelectric sensing materials and instable outputs caused by ambient environment significantly restrict their practical applications. In this work, a stable and reliable self‐powered chemical‐sensing system is proposed by coupling triboelectric effect and chemoresistive effect. The whole system is constructed as the demo of a self‐powered vehicle emission test system by connecting a vertical contact–separate mode TENG as energy harvester with a series‐connection resistance‐type gas sensor as exhaust detector and the parallel‐connection commercial light‐emitting diodes (LEDs) as alarm. The output voltage of TENG varies with the variable working states of the gas sensor and then directly reflects on the on/off status of the LEDs. The working mechanism can be ascribed to the specific output characteristics of the TENG tuned by the load resistance of the gas sensor, which is responded to the gas environment. This self‐powered sensing system is not affected by working frequency and requires no external power supply, which is favorable to improve the stability and reliability for practical application.