Superhydrophobic, Anti-Freezing and Multi-Cross-Linked Wearable Hydrogel Strain Sensor for Underwater Gesture Recognition.

Conductive hydrogel is considered to be one of the most potential sensing materials for wearable strain sensors. However, both the hydrophilicity of polymer chains and high water content severely inhibit the potential applications of hydrogel-based sensors in extreme conditions. In this study, a multicross-linked hydrogel was prepared by simultaneously introducing a double-network matrix, multiple conductive fillers, and free-moving ions, which can withstand an ultralow temperature below -80 °C. A superhydrophobic Ecoflex layer with a water contact angle of 159.1° was coated on the hydrogel using simple spraying and laser engraving methods. Additionally, the smart glove integrating five hydrogel strain sensors with a microprocessor was developed to recognize 12 types of diving gestures and synchronously transmit recognition results to smartphones. The superhydrophobic and antifreezing hydrogel strain sensor proposed in this study emerges promising potentials in wearable electronics, human-machine interfaces, and underwater applications.

Multilayer Perceptron Algorithm-Assisted Flexible Piezoresistive PDMS/Chitosan/cMWCNT Sponge Pressure Sensor for Sedentary Healthcare Monitoring.

Recently, the health problems faced by sedentary workers have received increasing attention. In this study, a pressure sensor based on a poly(dimethylsiloxane) (PDMS)/carboxylated chitosan (CCS)/carboxylated multiwalled carbon nanotube (cMWCNT) sponge was prepared to realize a portable, sensitive, comfortable, and noninvasive healthcare monitoring system for sedentary workers. The proposed piezoresistive pressure sensor exhibited exceptional sensing performances with high sensitivity (147.74 kPa-1), an ultrawide detection range (22 Pa to 1.42 MPa), and reliable stability (over 3000 cycles). Furthermore, the obtained sensor displayed superior capability in detecting various human motion signals. Based on the 4 × 4 sensing array and multilayer perceptron (MLP) algorithm model, a smart cushion was developed to recognize five types of sitting postures and supply timely reminders to sedentary workers. The piezoresistive sponge pressure sensor proposed in this study reveals promising potential in the fields of wearable electronics, healthcare monitoring, and human-machine interface applications.