All-fiber rotary micromotor based on laser-induced thermal convection

Micromotors based on fiber optical tweezers (OTs) hold exciting prospects for studying rotary motor proteins, observing the microscopic properties of fluids, and diagnosing diseases. In this paper, we report an all-fiber, OTs-based, rate-controllable, rotary micromotor using laser-induced thermal convection. The optical trapping force can stably trap a microparticle in water. The laser can heat a gold film on the fiber probe of the OTs to form a temperature gradient, leading to a water flow with a velocity gradient that continuously rotates the microparticle. Simulation results prove the feasibility of this method. In addition, experiments show that when the incident laser power is higher, the velocity gradient of water flow near the fiber probe is greater, and the microparticle rotates faster. The rotation rate varies from 12 to 80 rpm. This rotary micromotor has potential applications in microfluidic pumping, biopsy, micromanipulation, etc.