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

Abstract

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.).