A Maskless Process for Fabrication of Patterned Surfaces with Microscale Superhydrophobic Borders for High Throughput Droplet Microarray Printing

We demonstrate a novel and simple fabrication technique to create a 2D array of liquid capturing micro-regions separated by superhydrophobic borders on polydimethylsiloxane (PDMS). The pattern with microscale superhydrophobic borders was formed by transfer of nanostructures grown on a copper mesh. Our technique does not require the use of any sophisticated equipment, thus making it simple, cost-effective and easily scalable. The capturing regions defined by the superhydrophobic borders can trap droplets having volume as low as ~2.1 picolitres (pL) when exposed to a liquid. Trapped droplet volume depends on the dimension of the liquid capture region, which is determined by the pore opening (L) of the copper mesh. We demonstrate capture of various aqueous droplets of different sizes on different surfaces. These surfaces can be used in a variety of applications where cell culture in small volumes is required (e.g. cell differentiation, forming genome libraries etc.).