Ultra‐Robust and Sensitive Flexible Strain Sensor for Real‐Time and Wearable Sign Language Translation

Abstract

Flexible strain sensors with high sensitivity and high mechanical robustness are highly desirable for their accurate and long‐term reliable service in wearable human‐machine interfaces. However, the current application of flexible strain sensors has to face a trade‐off between high sensitivity and high mechanical robustness. The most representative examples are micro/nano crack‐based sensors and serpentine meander‐based sensors. The former one typically shows high sensitivity but limited robustness, while the latter is on the contrary. Herein, ultra‐robust and sensitive flexible strain sensors are developed by crack‐like pathway customization and ingenious modulation of low/high‐resistance regions on a serpentine meander structure. The sensors show high cyclic stability (10 000 cycles), strong tolerance to harsh environments, high gauge factor (>1000) comparable with that of the crack‐based sensor, and fast response time (<58 ms). Finally, the sensors are integrated into a wearable sign language translation system, which is wireless, low‐cost, and lightweight. Recognition rates of over 98% are demonstrated for the translation of 21 sign languages with the assistance of machine learning. This system facilitates achieving barrier‐free communication between signers and nonsigners and offers broad application prospects in gesture interaction.

Materials-Driven Soft Wearable Bioelectronics for Connected Healthcare

“…A cracked elastomer or nano-/microcrack has been intentionally generated on elastomers to bring ultrasensitivity for subtle strain detection. − The disconnection/reconnection between adjacent zip-like nanoscale crack junctions enabled sensitive resistivity responses to external mechanical stimuli achieving extremely large gauge factor and low signal-to-noise ratio (SNR) . The mechanical crack-based strain sensor was first inspired by the spider sensory system with a slit organ geometry .…”

Liquid Metal and Carbon Nanofiber-Based Strain Sensor for Monitoring Gesture, Voice, and Physiological Signals

“…40 According to the observations of SEM images in Figures 2b and 3f,k, the microspheres of LM, serving as an "island," could be electronically "bridged" by the microrobs of CNF. In the network, the conductive modes of LM and CNF are dominated by free-electrons 30,31 and off-domain π-electrons, 50 respectively. Hence, the conductivity of LM/CNF is determined by the slower one among them, i.e., the conductive mode of CNF.…”

“…28 Liquid-state conductors injected new energy into the study of soft strain sensors, such as the use of ionic conductive liquids to trace human motion with low hysteresis and overshoot 29 i.e., EGaIn) into the crack-based strain sensing mechanism to improve sensitivity in a wider range. 30,31 In addition, strain sensors in the shape of fibers, which are tailorable and suitable for weaving or knitting, have also attracted a lot of attention in the field of flexible strain sensors. 32−34 They can be produced by simply dip-coating elastic and piezoresistive materials onto stretchable insulating fibers.…”

Highly Stretchable Ti3C2Tx MXene-Integrated Phase Change Films for Solar-Thermal Harvesting and Infrared Stealth

“…On the other hand, flexible strain sensors based on conductive elastomers are able to respond to strain behavior by recording real-time changes in resistance and have great potential in the fields of motion recognition, − health care, − and artificial intelligence. − They eliminate the disadvantages of conventional rigid sensors, such as mechanical stiffness, high weight, and lack of portability, sparking a future-oriented revolution in electronics. − At the same time, switching solar energy into thermal energy, which can be stored in PCM thermal management system, is an efficient technique to realize the utilization of solar energy. , As a novel 2D material, MXene has attracted wide attention in the fields of sensor, − electromagnetic interference (EMI) shielding, energy storage, and infrared stealth , due to the significant advantages of abundant active groups at the end face, high electron density, and good processability. By integrating MXene into PCM composites for wearable solar-thermal conversion and storage, it is possible to further reduce the requirement for additional portable energy sources and improve the energy effectiveness of the electronic devices, as well as provide a warm environment suitable for the metabolism of the human body in cold outside conditions. − …”