Near-Linear Responsive and Wide-Range Pressure and Stretch Sensor Based on Hierarchical Graphene-Based Structures via Solvent-Free Preparation.

Flexible and wearable electronics have huge potential applications in human motion detection, human-computer interaction, and context identification, which have promoted the rapid development of flexible sensors. So far the sensor manufacturing techniques are complex and require a large number of organic solvents, which are harmful not only to human health but also to the environment. Here, we propose a facile solvent-free preparation toward a flexible pressure and stretch sensor based on a hierarchical layer of graphene nanoplates. The resulting sensor exhibits many merits, including near-linear response, low strain detection limits to 0.1%, large strain gauge factor up to 36.2, and excellent cyclic stability withstanding more than 1000 cycles. Besides, the sensor has an extraordinary pressure range as large as 700 kPa. Compared to most of the reported graphene-based sensors, this work uses a completely environmental-friendly method that does not contain any organic solvents. Moreover, the sensor can practically realize the delicate detection of human body activity, speech recognition, and handwriting recognition, demonstrating a huge potential for wearable sensors.

Capacitive Pressure Sensor with Wide-Range, Bendable, and High Sensitivity Based on the Bionic Komochi Konbu Structure and Cu/Ni Nanofiber Network.

High-performance flexible pressure sensors have an essential application in many fields such as human detection and human-computer interaction. Herein, on the basis of the dielectric layer of a bionic komochi konbu structure, we propose a low-cost and novel capacitive sensor that achieves high sensitivity and stability over a broad range of tactile pressures. Further, the flexible and durable electrode layer of the transparent junctionless copper/nickel-nanonetwork was prepared based on electrospinning and electroless deposition techniques, which ensured high bending stability and high cycle stability of our sensor. More importantly, because of the sizeable protruding structure and internal micropores in the elastomer structure we designed, the inward curling of the protruding structure and the effectual closing of the micropores increase the effective dielectric constant under the action of the compressive force, improving the sensitivity of the sensor. Measured response and relaxation time (162 ms) are 250 times faster than those of a conventional flat polydimethylsiloxane capacitive sensor. In addition, the fabricated capacitive pressure sensor demonstrates the ability to be used on wearable applications, not only to quickly recognize the tapping and bending of a finger but also to show that the pressure of the finger can be sensed when the finger grabs the object. The sensors we have developed have shown great promise in practical applications, such as human rehabilitation and exercise monitoring, as well as human-computer interaction control.