An optical platform for the production, trapping, manipulation and visualization of ultra-low interfacial tension emulsion droplets

Abstract

We discuss the design, implementation and performance of a novel platform for the production and optical control of ultra-low interfacial tension droplets in the 1-10 micron regime. A custom-designed, integrated microfluidic system allows the production of oil-in-water emulsion droplets of controllable size. This provides an optimised physical platform in which individual droplets are selected, trapped and shaped by holographic optical tweezers (HOTs) via extended optical landscaping. The 3D structure of the shaped droplet is interrogated by a combination of conventional brightfield imaging and fluorescent structured-illumination sectioning. We detail the problems and limitations of closedloop holographic control of droplet shape.