A conductive polyacrylamide hydrogel enabled by dispersion-enhanced MXene@chitosan assembly for highly stretchable and sensitive wearable skin

• Published in: Journal of materials chemistry. B, Materials for biology and medicine Vol. 9; no. 42; pp. 8862 - 887
• Main Authors: Liu, Yaqing, Xu, Daren, Ding, Yi, Lv, Xiaoxiao, Huang, Tingting, Yuan, Bolei, Jiang, Lin, Sun, Xueying, Yao, Yuanqing, Tang, Jun
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 03.11.2021
• Subjects: Acrylic Resins - chemistry; Acrylic Resins - pharmacology; Anti-Bacterial Agents - chemistry; Anti-Bacterial Agents - pharmacology; Antibacterial activity; Charge transfer; Chitosan; Chitosan - chemistry; Chitosan - pharmacology; Conductivity; Current carriers; Dispersion; Electric Conductivity; Escherichia coli - drug effects; Flexibility; Human motion; Humans; Hydrogels; Mechanical properties; Microbial Sensitivity Tests; Motion detection; Motion perception; MXenes; Nanocomposites - chemistry; Polyacrylamide; Self-assembly; Sensors; Skin; Staphylococcus aureus - drug effects; Strain; Wearable Electronic Devices; Wearable technology
• ISSN: 2050-750X; 2050-7518
• DOI: 10.1039/d1tb01798e

MXene is recognized as an ideal material for sensitive wearable strain sensors because of its unique advantages of conductivity, hydrophilicity and mechanical properties. However, conventional hydrogel sensors utilizing MXene as a conductive material inevitably encounter the excessive accumulation of MXene nanosheets during the process of synthesis, which limits the electron transmission, reduces the conductivity, and concurrently weakens the mechanical capability and sensitivity of sensors. Herein, we construct a dispersion-enhanced MXene hydrogel (DEMH) through a chitosan-induced self-assembly strategy for the first time. Charge transfer is carried out through the flow of a material or a collection of material microstructures, and thus the highly interconnected 3D MXene@Chitosan network provides fast transport channels for electrons, and the DEMH exhibits excellent conductivity and sensibility simultaneously. Besides, the electrostatic self-assembly between MXene and chitosan, and the supramolecular interactions between MXene, chitosan and polyacrylamide chain segment result in excellent mechanical strength (of up to 1900%) and flexibility of DEMH. Furthermore, the introduction of chitosan which possesses a high density of positively charged groups and MXene with semiconducting properties also endows sensor versatility, such as self-adhesion properties and antibacterial activity. This work develops a simple and cut-price strategy for combining MXene unaggregated into a hydrogel as a sensor with high conductivity, sensibility and flexibility. A simple and inexpensive strategy for avoiding self-stacking of two-dimensional conductive materials is proposed, which paves the way for a broad range of applications in electronic skin, human motion detection and intelligent devices. The DEMH exhibits excellent conductivity, sensibility and antibacterial activity simultaneously.