Acoustic shape-morphing micromachines.

Abstract

Shape-morphing mechanisms help organisms adapt to their environment and have inspired applications in advanced systems. Designing microrobots that are both miniaturized and capable of fast shape changes is challenging, as performance can be weakened at small scales. Ultrasound offers advantages such as fast response, repeatability, and programmability, making it suitable for enabling shape-morphing microrobots. Here, we introduce an acoustic micromachine composed of two microbubbles connected by a microhinge. Acoustic-field excitation generates interaction forces between the bubbles, enabling complete micromachine deformation within milliseconds. We also present design principles for programmable acoustic deformation, enabling both forward and inverse design, precise control, and information storage. By tuning the excitation amplitude, the micromachine can switch between multiple modes. As proof of concept, microlotus and microbird structures are demonstrated with controllable and stable performance.