Scaling Dielectrowetting Optical Shutters to Higher Resolution: Microfluidic and Optical Implications

A detailed study is reported on the implications of scaling dielectrowetting optical shutters to higher resolutions. Reducing droplet sizes from millimeters to 100 μm in diameter increases the relevance of microfluidic physics such as pinning, film breakup, and dewetting speed as well as optical physics such as transmission and diffraction. In addition, in this work we present improved material systems, including optimized dielectric stacks which reduce electrochemical degradation, and blended lower-viscosity fluids which increase dewetting speed. A higher-resolution device of ∼250 μm diameter demonstrates switching speeds of 70%. In addition to revealing science not previously discussed, this work has strong applied importance as scaling to higher resolutions is desirable for improving visual appearance in applications ranging from smart windows to electronic signage.