Ultrasonically-actuated liquid metal gallium micromotors with patterned ultrasound transducers

We present the design and characterization of a liquid gallium-based micro/nanomotor (LGNM) that enables ultrasonically actuated propulsion, dynamically reconfigurable collective swarming, and enhanced ultrasound imaging contrast. LGNMs were fabricated via a pressure-filtration templating technique, permitting precise, tunable control over their axial dimensions (1–15 μm) through systematic modulation of template pore size, filtration pressure, and processing time. Under an applied acoustic field, LGNMs undergo autonomous propulsion mediated by acoustic radiation forces, attaining velocities of up to 75 μm/s. By spatiotemporally modulating the ultrasound field across four orthogonal directions, we achieved high-fidelity trajectory-guided navigation—including planar tracing of the alphanumeric pattern “HIT”. Furthermore, varying the excitation frequency within the 100–120 kHz band induced reversible, programmable self-organization into distinct collective architectures, such as stripe-like and spoon-shaped configurations. These acoustically driven collective dynamics were visualized in real time using clinical-grade ultrasound imaging, thereby validating the LGNM platform as a reconfigurable, imaging-integrated, and therapeutically viable agent.