Microorganisms can move in complex media, respond to the environment and self-organize. The field of microrobotics strives to achieve these functions in mobile robotic systems of sub-millimetre size. However, miniaturization of traditional robots and their control systems to the microscale is not a viable approach. A promising alternative strategy in developing microrobots is to implement sensing, actuation and control directly in the materials, thereby mimicking biological matter. In this Review, we discuss design principles and materials for the implementation of robotic functionalities in microrobots. We examine different biological locomotion strategies, and we discuss how they can be artificially recreated in magnetic microrobots and how soft materials improve control and performance. We show that smart, stimuli-responsive materials can act as on-board sensors and actuators and that ‘active matter’ enables autonomous motion, navigation and collective behaviours. Finally, we provide a critical outlook for the field of microrobotics and highlight the challenges that need to be overcome to realize sophisticated microrobots, which one day might rival biological machines.

微生物可以在复杂的介质中移动，对环境做出反应并自我组织。微机器人领域致力于在亚毫米大小的移动机器人系统中实现这些功能。但是，将传统的机器人及其控制系统小型化到微尺度并不是可行的方法。开发微型机器人的一种有前途的替代策略是直接在材料中执行感测，驱动和控制，从而模仿生物物质。在这篇评论中，我们讨论了在微型机器人中实现机器人功能的设计原理和材料。我们研究了不同的生物运动策略，并讨论了如何在磁性微型机器人中人工重建它们以及软材料如何改善控制和性能。我们证明那很聪明，刺激响应材料可以充当车载传感器和执行器，而“活性物质”可以实现自主运动，导航和集体行为。最后，我们对微型机器人技术领域提供了重要的展望，并强调了实现复杂的微型机器人需要克服的挑战，有一天它可能会与生物机器匹敌。