Microdroplet Patterning: Designer Hydrophilic Regions Regulate Droplet Shape for Controlled Surface Patterning and 3D Microgel Synthesi

1. Matthew J. Hancock^4,†, 
2. Fumiki Yanagawa^4,†, 
3. Yun-Ho Jang⁴, 
4. Jiankang He^4,5, 
5. Nezamoddin N. Kachouie⁴, 
6. Hirokazu Kaji^4,6, 
7. Ali Khademhosseini^1,2,3,4,*

Article first published online: 30 JAN 2012

DOI: 10.1002/smll.201290019

The cover image shows how the shape of micro- and nanodroplets can be controlled by patterning surfaces with special hydrophilic regions surrounded by hydrophobic boundaries. Shaped droplets may be used as a simple tool to controllably pattern planar surfaces with microparticles and cells. Under spiral droplets, a gradient deposition pattern is observed. Shaped droplets of prepolymer solution may also be crosslinked to synthesize microgels with tailored 3D geometry. Finite element simulations provide a design platform by linking the shape of the hydrophilic regions to that of the droplets, microgels, and particle deposition patterns.