Bipolar Photoelectrochemistry for Phase-Modulated Optoelectronic Hybrid Nanomotor.

Complex micro/nanorobots may be constructed by integrating several independent, controlled nanomotors for high degrees of freedom of maneuvering and manipulation. However, designing nanomotors with distinctive responses to the same global stimuli is challenging due to the nanomotors' simple structure and limited material composition. In this work, we demonstrate that a nanomotor can be designed with the same principles of electronic circuits, where the motion of semiconductor particles can be controlled with synchronized electric and optical signals. This technique relies on transient bipolar photoelectrochemistry in semiconductor microparticles, where the reaction site selectivity is realized by modulating the light pulse in the time domain. Due to the microparticles' intrinsic resistance and surface capacitance, the nanomotors can be designed as an electronic circuit, enabling distinctive responses to the global electric/optical field and achieving the desired movement or deflection/rotation. This work gives new insight into the manipulation technique for independent and untethered nanomotor control. Ultimately, it exploits the potential for particle sorting based on geometry in time and frequency domain modulation.