Liu Yunsong, Zheng Xiong
College of Mechanical and Vehicle Engineering, Hunan University, Changsha 410082, China.
School of Mechanical Engineering, Dalian University of Technology, Dalian 116081, China.
Materials (Basel). 2024 Jul 25;17(15):3679. doi: 10.3390/ma17153679.
Bio-inspired hydrogel robots have become promising due to their advantage of the interaction safety and comfort between robots and humans, while current hydrogel robots mainly focus on underwater movement due to the hydration-dehydration process of thermo-responsive hydrogels, which greatly limits their practical applications. To expand the motion of the thermo-responsive hydrogel robot to the ground, we constructed a hydrogel robot inspired by a caterpillar, which has an anisotropic double-layered structure by the interfacial diffusion polymerization method. Adding PVA and SA to PNIPAm will cause different conformation transitions. Therefore, sticking the two layers of hydrogel together will form a double-layer anisotropic structure. The ultra-high hydrophilicity of PVA and SA significantly reduces the contact angle of the hydrogel from 53.1° to about 10° and reduces its hydration time. The responsive time for bending 30° of the hydrogel robot has been greatly reduced from 1 h to half an hour through the enhancement of photo-thermal conversion and thermal conductivity via the addition of FeO nanoparticles. As a result, the fabricated hydrogel robot can achieve a high moving speed of 54.5 mm·h on the ground. Additionally, the fabricated hydrogel has excellent mechanical strength and can endure significant flexibility tests. This work may pave the road for the development of soft robots and expand their applications in industry.
受生物启发的水凝胶机器人因其在机器人与人类之间的交互安全性和舒适性方面的优势而变得很有前景，而目前的水凝胶机器人由于热响应水凝胶的水合-脱水过程，主要专注于水下运动，这极大地限制了它们的实际应用。为了将热响应水凝胶机器人的运动扩展到地面，我们构建了一种受毛毛虫启发的水凝胶机器人，它通过界面扩散聚合法具有各向异性的双层结构。在聚N-异丙基丙烯酰胺（PNIPAm）中添加聚乙烯醇（PVA）和海藻酸钠（SA）会导致不同的构象转变。因此，将两层水凝胶粘在一起会形成双层各向异性结构。PVA和SA的超高亲水性显著降低了水凝胶的接触角，从53.1°降至约10°，并缩短了其水合时间。通过添加FeO纳米颗粒增强光热转换和热导率，水凝胶机器人弯曲30°的响应时间从1小时大幅缩短至半小时。结果，制造的水凝胶机器人在地面上可以实现54.5毫米/小时的高移动速度。此外，制造的水凝胶具有优异的机械强度，能够承受显著的柔韧性测试。这项工作可能为软机器人的发展铺平道路，并扩大它们在工业中的应用。
