Droplet microrobotic structures for compartmentalised biochemistry and organoid engineering

Microrobotic structures formed from liquid materials offer certain advantages of reconfigurability and biochemical compatibility at microscopic scales. Here, we use electrothermally driven flow dynamics to prepare single or multi-unit reconfigurable liquid droplet microrobotic structures with diverse cytomimetic properties. The microrobotic structures are constructed by the integrated assembly of precision-eluted lipid-coated water-in-oil emulsions, engineered with transmembrane protein-based pores and mechanosensitive channels, and augmented with encapsulated plasmids, active nanoparticles and brain organoids. The reconfigurable nature of the microrobotic structure is enabled by electrically conductive, liquid-based microfluidic circuits and electrodes. Specifically, we program thermal convectional flows to control droplet navigation, spatial assembly and actuation in fluidic environments. The droplet microrobot structures exhibit a range of cytomimetic properties, including, signal-mediated transcription/translation (RNA/protein synthesis), transmembrane-mediated chemical communication, autonomous environmental sensing and inter-droplet membrane fusion and integration. The latter process is employed to deliver biochemical reagents and quantum dots into human brain organoids housed within the droplet microrobotic structures as a step towards on-site tissue engineering and biohybrid robots. Our results demonstrate that thermotactic synthetic cells can be spatially organised into programmable multi-unit structures with potential applications in bioengineering, sensing and targeted delivery.