Zemin Li,Jiaoya Huang,Runhui Zhou,Ziyu Chen,Wenchao Gao,Jiang He,Rongrong Bao,Caofeng Pan
Hydrogels possess several interesting characteristics and have attracted increasing attention for flexible interactive strain-sensing. However, hydrogel strain sensors are easily influenced by temperature because of the intrinsic characteristics of the materials, thus, their sensing accuracy is significantly affected. Herein, a strategy is proposed to eliminate the influence of temperature by building an in-situ hydrogel temperature sensor next to the strain sensor to monitor ambient temperature changes and simultaneously correct the strain signal. By introducing silicon nanoparticles and modified graphene, the hydrogel exhibits a good balance between conductivity and stretchability. The hydrogel strain sensor exhibits a working range of up to 1000% and a sensitivity of 8.1. It can monitor human movement and shows good stability. Moreover, the hydrogel-based sensor demonstrates an impressive thermal response sensitivity (−7.16% °C −1 ). This bimodal sensor not only realizes the decoupling of the strain sensor from the temperature but protects the temperature sensor from the influence of strain. More importantly, the device is also able to accurately control the manipulator under dynamic temperatures, proving the feasibility of the design. This strategy provides a new method to eliminate the influence of temperature on strain sensing and assists in the development of the interactive-sensing field.
Human skin achieves high sensitivity and a wide range of tactile perception through its gradient structure and the synergistic function of various receptors. However, significant challenges remain in achieving multifunctional synergy enhancement for artificial skin. This study develops a soft-tough bilayer gradient hydrogel based on a salting-out and ion coordination toughening strategy, achieving high sensitivity (7.35 kPa −1 , 0–3 kPa) and a broad stress sensing range (0–75.44 kPa). The soft layer is designed with a low-density polyacrylamide (PAM) network, where weak chemical crosslinking improves both elasticity and sensitivity. Meanwhile, the tough layer is formed by a high-density dual crosslinked network of polyacrylamide /polyvinyl alcohol/sodium alginate, followed by post-treatment in ZnSO 4 solution. The combined effects of salting-out and ion coordination greatly enhance toughness, extend the stress detection range, and strengthen interlayer adhesion. Furthermore, this study integrates the hydrogel into a robotic arm and develops a gel-controller-computer tactile feedback system that simulates the conditioned reflex mechanism, enabling non-destructive recognition and precise grasping of objects with varying hardness. Moreover, the bilayer gradient hydrogel-based sensor facilitates comprehensive recognition of an object's weight and shape. This research offers a novel approach to advancing artificial skin, bioinspired robotics, and intelligent sensing technologies.
Xiaoyu Ma,Xinming Shi,Yang Wang,Weijie Xiong,Caihua Xiong,Jinhao Yang,Lijun You,Shaoyun Wang
Conductive hydrogels with stretchability, breathability and long-term stability have attracted increasing attention for the applications in interactive wearable devices , artificial prosthetics, and intelligent robots. In this paper, a stretchable (up to 254 %), well breathable (vapor transmission up to 1.231×10 −2 g·cm −2 ·h −1 ), and stable conductive (1.21 S/m) hydrogel films (Gel/PPy/Ag) was prepared by gel-template immersion method using gelatin as gel networks, polypyrrole (PPy) and silver (Ag) as conductive reinforcing filler and Span 80 as emulsion template. The film could maintain flexibility and conductivity after stored in an environment of –20 °C or 25 °C for 20 days. The excellent frost resistance and water retention ensured the practical application of the porous organic hydrogel film with environmental adaptability and long-term stability. The strain sensor made from the Gel/PPy/Ag films presented excellent sensitivity (GF reached 2.034), good durability, fast response (0.34 s) and recovery ability (0.36 s). It monitored weak and vigorous human motions effectively and sensitively. The Gel/PPy/Ag flexible electrodes realized the real-time sensitive detection of human Electrocardiogram (ECG) and electromyogram (EMG) signals and precision sensing control of the manipulator arm. The Gel/PPy/Ag hydrogel and the prepared flexible electronic devices have broad application prospects in the field of health monitoring, motion monitoring, operation control and other soft electronic devices.
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