The field of soft actuators is dominated by elastomers that experience mechanical deformations in response to external stimuli. In this context, magnetic stimuli attract considerable interest because of their easy application, tunability, fast response, remote actuation, and safe penetration in biological environments. Since very recently, research interests in the field are being redirected towards hydrogels, which could virtually replace elastomers, overcoming their limitations and expanding the field of application of soft actuators. The mechanical actuation of hydrogels is a nascent field full of challenges, such as achieving reliable and significant responsiveness. Here we demonstrate that the combination of a physical polymer hydrogel with a dispersed phase consisting of clusters of magnetic particles, results in magnetic hydrogel composites that exhibit high and reversible elongation in response to magnetic stimuli. Our analyses show that this response is strongly dependent on the matrix elasticity, the concentration of magnetic particles, and the particle distribution within the network of polymer nanofibres. Our strategy for the maximization of the response of magnetic hydrogels should be a catalyst for the development of novel applications of composite hydrogels, such as a valve remotely actuated by a magnetic field that we also present here as a proof-of-concept.

软致动器领域由弹性体主导，这些弹性体在响应外部刺激时会发生机械变形。在这种情况下，磁刺激因其易于应用、可调性、快速响应、远程驱动和在生物环境中的安全渗透而引起了相当大的兴趣。最近，该领域的研究兴趣转向水凝胶，它实际上可以替代弹性体，克服其局限性并扩大软致动器的应用领域。水凝胶的机械驱动是一个充满挑战的新兴领域，例如实现可靠和显着的响应能力。在这里，我们证明了物理聚合物水凝胶与由磁性粒子簇组成的分散相的组合，导致磁性水凝胶复合材料在磁刺激下表现出高且可逆的伸长率。我们的分析表明，这种响应强烈依赖于基质弹性、磁性颗粒的浓度以及聚合物纳米纤维网络内的颗粒分布。我们最大化磁性水凝胶响​​应的策略应该是开发复合水凝胶新应用的催化剂，例如由磁场远程驱动的阀门，我们在此也作为概念验证提出。