A Multifunctional and Selective Ionic Flexible Sensor with High Environmental Suitability for Tactile Perception

• Published in: Advanced functional materials Vol. 34; no. 6
• Main Authors: Yuan, Shen, Bai, Ju, Li, Shengzhao, Ma, Nan, Deng, Shihao, Zhu, Hao, Li, Tie, Zhang, Ting
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01.02.2024
• Subjects: Biomimetics; Electrical resistivity; Elongation; Flexible components; freeze resistance; Freezing; Frost resistance; Humanoid; Hydrogels; ionic flexible sensors; multifunctional hydrogels; Nanocomposites; Perception; selective response; Sensors; Softness; Tactile discrimination; water retention
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202309626

Inspired by the tactile sensory mechanism of human skin, ionic hydrogels‐derived ionic flexible sensors have attracted much attention since they can produce output signals that match the recognition mode of nerves, showing a potential application in the human‐machine interaction. Unfortunately, the practical sensing properties of ionic hydrogels are restricted by the drawbacks of hydroelastic instability and non‐selective response ability, such as poor mechanical strength, irretentive solvent retaining capacity, and low‐temperature intolerance. Herein, in this study, a novel physical‐crosslink enhanced ionic hydrogel‐PVA/PEG/TA‐MXene‐Na+/Li+ (PPM‐NL) nanocomposite is prepared and shows well comprehensive properties of mechanical strength (400% elongation at break, 0.93 MPa), electrical conductivity (8.1 S m−1), tear resistance, self‐healing and anti‐freezing/drying features (93% water retention after sixty days and frost resistance −27 °C). The PPM‐NL hydrogel‐derived flexible sensor displays selective response behavior to tensile and compressive deformation with high sensitivity (G = 1.12) and rapid response time (only 60 ms). Further, this ionic flexible device is applied to monitor the joint motions of humanoid hands and integrated into manipulators to recognize the thickness and softness of objects, showing superior environmental stability. It can be believed that this ionic flexible sensor will provide inspiration for developing next‐generation biomimetic tactile perception of robots. Inspired by the topological structure and sensing mechanism of finger skin, an innovative sensitive material‐PVA/PEG/TA‐MXene‐Na+/Li+ ionic hydrogel is proposed by an ingenious combination of repeated freeze‐thawing and salting‐out strategy, exhibiting well comprehensive properties of mechanical strength (400% elongation), tear resistance, self‐healing and anti‐freezing/drying features (93% water retention after sixty days), and selective response to tensile and compressive deformation.