Hydrodynamic Manipulation of 2D and 3D Microstructure Assembly Using Robotic Acoustic Streaming Tweezers

Precise and contactless manipulation of microstructures remains a major challenge in microassembly and lab-on-chip systems. Here, we introduced a Robotic Acoustic Streaming Tweezers (RAST) system that used an MEMS-based gigahertz resonator to generate localized acoustic streaming for programmable 2D and 3D manipulation of microgels. By tuning the power and height of the resonator, RAST achieved versatile, gentle operations of microgels. Our results demonstrated that the low-power enabled precise 2D translation and planar assembly of linear, layered, and patterned structures; intermediate power induced controlled flipping and rotation for orientation-specific alignment; and high power lifted microgels into 3D vortex traps, enabling accurate spatial nesting along guiding scaffolds. By integrating computer vision and path-planning algorithms, the system also enabled the high-throughput assembly of multiple microgels without human intervention. The RAST system offered a mild, label-free, and powerful strategy for complex microscale construction, providing a robust and scalable new solution for microrobots, biomedical devices, and advanced microfabrication technologies.