Droplet IO: Programmable Droplets for Human-Material Interaction

Sept. 1, 2017


In this thesis, I propose aqueous droplets as a form of programmable material that can computationally transform its physical properties. Liquid matter can undergo physical transformation through interfacial forces and surface tension. I introduce a system called DropletIO to regulate interfacial forces through a programmable electric eld. The system can actuate and sense macro-scale (micro-liter to milli-liter) droplets on arbitrary planar and curved surfaces. The system can precisely move, merge, split, and change shape of droplets and thus enables a range of applications with human interactivity, information displays, parallelized programmable chemistry and dynamically tunable optics.

DropletIO system uses electrowetting on dielectric (EWOD) to manipulate droplets. EWOD is a physical phenomenon where a polar droplet on a dielectric surface is at- tracted to a charged electrode. I constructed EWOD arrays with integrated actuation and sensing on inexpensive printed circuit boards that can scale to arbitrarily large areas and di erent form factors. Additionally, in this thesis I discuss how semicon- ductor device scaling applies to electrowetting for smaller volume droplets and hence miniaturized programmable lab-on-a-chip.

Droplet based microfluidics is extensively used in biology and chemistry. In this thesis I describe two novel uid manipulation mechanism for microfluidics. First, I show an approach for splitting aqueous droplets on an open digital micro fluidic platform and thus a system capable of performing a complete set of micro fluidic operations on an open surface. Second, I demonstrate how electrowetting platforms can handle large volume fluids, and hence enable a new direction in programmable fluid handling called digital millifluidics.

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