Collaborative Research: Dynamic Manipulation of Micro-scale Liquid-Liquid Interfaces within Complex Droplets for Tunable Optics

Optical materials that can be tuned and adjusted in real time have become important in many applications. These include display technology, compact imaging devices, biomedical sensors, and point-of-care diagnostic tools. Liquids have many properties that would be beneficial for tunable optics. Liquids are deformable, have a broad range of adjustable properties, and have ultra-smooth surfaces with variable curvature. These characteristics could be particularly beneficial in tunable micro-lenses. In this project, the investigators will examine how complex droplets behave as tunable optical materials. Here, the complex droplets will be composed of two or three immiscible oils within an aqueous outer phase. A combination of experiments and analytical and computational modeling will be used. The aim is to provide a comprehensive understanding of the opportunities for realizing novel fluid-based optical technologies.

Micron-scale optical elements have contributed significantly to the miniaturization of devices and instrumentation. They have been used in integral imaging and 3D displays, spatial light modulators, endoscopes, plenoptic cameras, and solar concentrators. Dynamically switchable reflective micro-optics, based on digital micro-mirror displays and continuously reconfigurable absorptive pixel technology enabled by liquid crystal displays, have enabled transformative advances in optical technology. Similarly, dynamic refractive micro-optics are poised to complement and extend the capabilities of present micro-optical devices. Although not yet a staple in the optical engineer's toolbox, liquids offer tremendous flexibility, design advantages, miniaturization promise, and manufacturing benefits in applications that require tunability. Despite the promise of using liquids within optical devices, the same malleability and sensitivity to many stimuli that make liquids so valuable for tunable optics can also make them difficult to control with the precision required for optical applications. A deeper fundamental understanding of strategies for liquid interface manipulation to fine-tune a fluid optical element and new approaches for controlling fluid-fluid interfaces within complex multiphase systems are critical for the advancement of optofluidic devices. In this collaborative effort, researchers aim to demonstrate that careful design of the composition and morphology of multiphase emulsion droplets provides a powerful strategy to form tunable lenses and micro-scale total internal reflection modules. This research pushes the boundaries of current liquid optics by exploring how droplets containing multiple reconfigurable fluid interfaces can be used to control lensing, correct for optical aberrations, and enable efficient spectral dispersion through total internal reflection. Understanding how liquid interfaces can be addressed independently or in tandem to dynamically tune the optical behavior of complex droplets will enable applications of fluids as optical components. Through this collaboration, the team aims to bring together optical theory with an enhanced understanding of how to manipulate multiphase liquids with the goal of broadening the role that complex fluids play in the realm of dynamic optical materials. Given the ease by which the complex droplets used in this proposal can be fabricated and reconfigured, the researchers will use fluid optical materials as a teaching tool to introduce K-12 students and educators to concepts in surface science. Broader societal impact of the research program is expected through applications in point-of-care diagnostics. Development of more sensitive, quantitative, and low cost platforms for health monitoring will have far-reaching global impact on healthcare.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.