Hassan Hamna, Khan Mansoor, Shah Luqman Ali, Yoo Hyeong-Min
Polymer Laboratory, National Centre of Excellence in Physical Chemistry, University of Peshawar, Peshawar, 25120, Pakistan.
School of Mechanical Engineering, Korea University of Technology and Education (KOREATECH), Cheonan 31253, Republic of Korea.
J Mater Chem B. 2025 Apr 16;13(16):4796-4808. doi: 10.1039/d4tb02709d.
Soft, stretchable, and smart strain-sensing hydrogels have attracted significant attention due to their broad applicability in emerging fields. However, developing hydrogel-based strain-sensing materials with finely tuned mechanical and sensing properties remains challenging, primarily due to the inherent brittleness of traditionally fabricated hydrogels. In this study, a novel flexible strain- and epidermis-sensitive sensor was designed using a cellulose nanocrystal (CNC)-mediated acid functionalized multiwalled carbon nanotube (A-MWCNT)-reinforced double-network conductive hydrogel. This dual-network hydrogel system was fabricated by integrating a covalently crosslinked acrylamide (Amm) and [2-(acryloyloxy) ethyl] trimethyl-ammonium chloride (AETAC) with a physically crosslinked network of A-MWCNTs, which were uniformly dispersed CNCs. Incorporating hydrogen bonding and strong electrostatic interactions within the physical network introduced reversible sacrificial bonds, significantly enhancing the hydrogel's mechanical strength. The hydrogel exhibited mechanical and sensing performance, including sufficient stretchability (431.6%), remarkable sensitivity, a gauge factor (GF) of 4.32 at 400% strain, toughness of 65.6 kJ m, Young's modulus of 1.5 kPa, and rapid response and recovery times of 100 msec. Furthermore, it demonstrated excellent cycling stability over 100 cycles and effective sensing capabilities across a broad strain range, from small deformations (5%) to large strains (400%). The conductivity of 0.09 S m, facilitated by the formation of conduction pathways through the AETAC and A-MWCNTs, further enhanced its performance. Moreover, the hydrogel exhibited practical applicability in detecting various large-scale and physiological human movements. Functioning as a wearable electronic skin, it represents a highly flexible and adaptable material suitable for applications in soft robotics, flexible sensors, and health monitoring devices.
柔软、可拉伸且智能的应变传感水凝胶因其在新兴领域的广泛适用性而备受关注。然而，开发具有精细调节的机械和传感性能的水凝胶基应变传感材料仍然具有挑战性，主要是因为传统制造的水凝胶固有的脆性。在本研究中，使用纤维素纳米晶体（CNC）介导的酸功能化多壁碳纳米管（A-MWCNT）增强的双网络导电水凝胶设计了一种新型的柔性应变和表皮敏感传感器。这种双网络水凝胶系统是通过将共价交联的丙烯酰胺（Amm）和[2-（丙烯酰氧基）乙基]三甲基氯化铵（AETAC）与A-MWCNT的物理交联网络整合而成，A-MWCNT均匀分散在CNC中。在物理网络中引入氢键和强静电相互作用引入了可逆的牺牲键，显著提高了水凝胶的机械强度。该水凝胶表现出机械和传感性能，包括足够的拉伸性（431.6%）、显著的灵敏度、在400%应变下的应变系数（GF）为4.32、韧性为65.6 kJ m、杨氏模量为1.5 kPa以及100毫秒的快速响应和恢复时间。此外，它在100个循环中表现出优异的循环稳定性，并且在从小变形（5%）到大应变（400%）的宽应变范围内具有有效的传感能力。通过AETAC和A-MWCNT形成传导路径促进的0.09 S m的电导率进一步提高了其性能。此外，该水凝胶在检测各种大规模和人体生理运动方面具有实际适用性。作为可穿戴电子皮肤，它代表了一种高度灵活且适应性强的材料，适用于软机器人、柔性传感器和健康监测设备等应用。
