Dynamics analysis of trapped particle in angular misaligned dual-fiber optical trap

In a dual-fiber optical trap system, precise alignment of the fibers is critical for trapping efficiency. Any transverse or angular misalignment will significantly affect operational effectiveness. We conduct simulations and analyses of the force and motion trajectory of a 5-μm radius microsphere within a dual-fiber optical trap, considering the angular misalignment and flow velocity of the ambient liquid. We demonstrate that with the increase in misalignment angle, the motion of the microsphere shifts among stable capture, spiral motion, orbital rotation, and escape states. Furthermore, the motion state of captured microspheres is influenced by the flow velocity of the ambient liquid. We enrich the motion model of microspheres in dual-beam optical traps within microfluidic chips and pave the way for the measurement of liquid velocity and viscosity in the microfluidic chip.