Optical Manipulation of Microparticles in Fluids Using Modular Optical Tweezers

Biophysical, biochemical, and biomechanical properties are vital in understanding the root cause of diseases and in finding appropriate treatment. The advent of optical tweezers (OT) has made it additionally convenient to study these properties and their interactions with the surrounding environment. This paper focuses on the trapping and manipulation of microparticles using OT integrated with a spatial light modulator (SLM). Along with finding the appropriate trapping drive current for trapping a single silica microbead $(2 \mu \mathrm{m}$ in diameter), the relation of trapping diameter and the laser drive current is also evaluated. The trapping area of the laser was directly proportional to the laser drive current. Utilizing the SLM, multiple microparticles were trapped and manipulated using an image sequence generated for circular and square patterns with a maximum refresh rate of 3.33 fps. Furthermore, motion analysis of the silica microbeads was conducted to evaluate the maneuverability of the OT system. In particular, the optical manipulation capabilities of the microbeads were assessed with variation in laser power and path generated by SLM.