Multiphoton‐Printed Microrobotic Arrays Powered by Discrete, Monolithically Integrated Hydrogel Actuators

Functional surfaces enable sensing, attachment, and read‐write capabilities in a range of robotic applications. For biomedicine, intelligent surfaces can enable actuation for diagnostics and targeted drug delivery. Pushing resolution limits in additive manufacturing techniques enables the development of microscale structures with increasing functionality to form 2D arrays of 3D reconfigurable microdevices. The ability to fabricate arrays of modular microtools with discrete functionality or as interacting structures can enhance lab‐on‐a‐chip technologies and diagnostic tools, creating surface‐based micromachine assemblies. In this paper, we demonstrate hybrid material actuators fabricated in arrays of new microtools on 2D surfaces. We demonstrate a new fabrication method that builds environmentally controlled, hybrid material, compliant microdevices in planar arrays. In this approach, individual hydrogels are monolithically integrated within arrays of 3D printed compliant structures. Environmental changes actuate the conical gels to translate vertical swelling over 180° of tool motion. Mechanism performance is tested by displacement experiments and validated with kinematic models. Lastly, we demonstrate the platform with a 400‐pixel array that responds to environmental changes to reveal programmed images. This new fabrication method, combined with the modular microactuators, expands micromachine design freedom to advance the capabilities of reconfigurable intelligent surfaces. In the future, these surfaces may advance soft robotic systems, enhance active coatings, and enable analyte sensing in human‐in‐the‐loop micromachines.