Bi-phase emulsion droplets as dynamic fluid optical systems

¹ Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
² Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, USA.
³ Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany.
⁴ Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.

^* Corresponding author: mkolle@mit.edu

Published online: 10 September 2019

Abstract

Micro-scale optical components play a critical role in many applications, in particular when these components are capable of dynamically responding to different stimuli with a controlled variation of their optical behavior. Here, we discuss the potential of micro-scale bi-phase emulsion droplets as a material platform for dynamic fluid optical components. Such droplets act as liquid compound micro-lenses with dynamically tunable focal lengths. They can be reconfigured to focus or scatter light and form images. In addition, we discuss how these droplets can be used to create iridescent structural color with large angular spectral separation. Experimental demonstrations of the emulsion droplet optics are complemented by theoretical analysis and wave-optical modelling. Finally, we provide evidence of the droplets utility as fluidic optical elements in potential application scenarios.