An automated platform for assembling light-powered hydrogel microrobots and their subsequent chemical binding

Abstract

This paper presents light powered hydrogel microrobots (100 μm), that are directed to specific locations in their environment by an automated platform. The microrobots are actuated by focused laser light and crawl in aqueous environments by periodic volumetric changes of a section of their bodies. The platform consists of a stage, manipulated by stepper drivers and controlled by a Raspberry PI 4. This positions the laser light in the desired locations to move microrobots towards a goal location. The microrobots are localized via a microscope camera and repetitive usage of an algorithm based on Hough Gradient Method. The optimal position for the laser is chosen before every step so that the disk reaches the goal as fast as possible. Multiple disks are moved to form a formation of predefined geometry. An algorithm for finding the optimum sequence of disk movements to suitable positions is introduced. Subsequently, the disks are bound together chemically, using local UV illumination as the binding trigger. The bound formation can perform useful tasks, such as pushing and depositing a cargo at a target location.