In the last decades, additive manufacturing (AM), also called three-dimensional (3D) printing, has advanced micro/nano-fabrication technologies, especially in applications like lightweight engineering, optics, energy, and biomedicine. Among these 3D printing technologies, two-photon polymerization (TPP) offers the highest resolution (even at the nanometric scale), reproducibility and the possibility to create monolithically 3D complex structures with a variety of materials (e.g. organic and inorganic, passive and active). Such active materials change their shape upon an applied stimulus or degrade over time at certain conditions making them dynamic and reconfigurable (also called 4D printing). This is particularly interesting in the field of medical microrobotics as complex functions such as gentle interactions with biological samples, adaptability when moving in small capillaries, controlled cargo-release profiles, and protection of the encapsulated cargoes, are required. Here we review the physics, chemistry and engineering principles of TPP, with some innovations that include the use of micromolding and microfluidics, and explain how this fabrication schemes provide the microrobots with additional features and application opportunities. The possibility to create microrobots using smart materials, nano- and biomaterials, for in situ chemical reactions, biofunctionalization, or imaging is also put into perspective. We categorize the microrobots based on their motility mechanisms, function, and architecture, and finally discuss the future directions of this field of research.

在过去的几十年中，增材制造 (AM)，也称为三维 (3D) 打印，拥有先进的微/纳米制造技术，特别是在轻量化工程、光学、能源和生物医学等应用中。在这些 3D 打印技术中，双光子聚合 (TPP) 提供了最高的分辨率（即使在纳米级）、再现性和使用各种材料（例如有机和无机、被动和主动）创建整体 3D 复杂结构的可能性. 这种活性材料在施加刺激时会改变其形状或在某些条件下随时间降解，从而使它们具有动态性和可重构性（也称为 4D 打印）。这在医学微型机器人领域尤其有趣，因为它具有复杂的功能，例如与生物样本的温和相互作用，需要在小毛细管中移动时的适应性、受控的货物释放曲线以及对封装货物的保护。在这里，我们回顾了 TPP 的物理、化学和工程原理，包括使用微成型和微流体技术的一些创新，并解释了这种制造方案如何为微型机器人提供额外的功能和应用机会。使用智能材料、纳米和生物材料制造微型机器人的可能性，用于 并解释这种制造方案如何为微型机器人提供额外的功能和应用机会。使用智能材料、纳米和生物材料制造微型机器人的可能性，用于 并解释这种制造方案如何为微型机器人提供额外的功能和应用机会。使用智能材料、纳米和生物材料制造微型机器人的可能性，用于原位化学反应、生物功能化或成像也被考虑在内。我们根据微型机器人的运动机制、功能和架构对微型机器人进行分类，最后讨论该研究领域的未来方向。