Small-scale soft-bodied machines that respond to externally applied magnetic field have attracted wide research interest because of their unique capabilities and promising potential in a variety of fields, especially for biomedical applications. When the size of such machines approach the sub-millimeter scale, their designs and functionalities are severely constrained by the available fabrication methods, which only work with limited materials, geometries, and magnetization profiles. To free such constraints, here, we propose a bottom-up assembly-based 3D microfabrication approach to create complex 3D miniature wireless magnetic soft machines at the milli- and sub-millimeter scale with arbitrary multimaterial compositions, arbitrary 3D geometries, and arbitrary programmable 3D magnetization profiles at high spatial resolution. This approach helps us concurrently realize diverse characteristics on the machines, including programmable shape morphing, negative Poisson’s ratio, complex stiffness distribution, directional joint bending, and remagnetization for shape reconfiguration. It enlarges the design space and enables biomedical device-related functionalities that are previously difficult to achieve, including peristaltic pumping of biological fluids and transport of solid objects, active targeted cargo transport and delivery, liquid biopsy, and reversible surface anchoring in tortuous tubular environments withstanding fluid flows, all at the sub-millimeter scale. This work improves the achievable complexity of 3D magnetic soft machines and boosts their future capabilities for applications in robotics and biomedical engineering.

响应外加磁场的小型软体机器因其独特的能力和在各个领域的潜力而引起了广泛的研究兴趣，特别是在生物医学应用方面。当此类机器的尺寸接近亚毫米级时，它们的设计和功能受到现有制造方法的严重限制，这些制造方法仅适用于有限的材料、几何形状和磁化分布。为了消除这些限制，我们提出了一种自下而上的基于组装的 3D 微细加工方法，以创建具有任意多材料成分、任意 3D 几何形状和任意可编程 3D 的毫米和亚毫米尺度的复杂 3D 微型无线磁软机器高空间分辨率的磁化分布。这种方法帮助我们同时实现机器上的各种特性，包括可编程形状变形、负泊松比、复杂的刚度分布、定向关节弯曲和形状重构的再磁化。它扩大了设计空间并实现了以前难以实现的与生物医学设备相关的功能，包括生物流体的蠕动泵送和固体物体的运输、主动靶向货物运输和交付、液体活检以及在曲折管状环境中的可逆表面锚定流体流动，都在亚毫米级。这项工作提高了 3D 磁软机器可实现的复杂性，并提高了它们在机器人和生物医学工程中应用的未来能力。