Microscale Oil-Covered Cell Array (MOCCA): A droplet array for high-content single-cell analysis and imaging

A simple, low-cost technique for high throughput single-cell analysis, Microscale Oil-Covered Cell Array (MOCCA), is presented in this paper. Corresponding to recent research on single cell analysis, simple devices for isolated cell chambers are urgently needed and long sought-after. Instead of using microfabricated solid structures to capture cells, MOCCA isolates cells in discrete aqueous droplets that are separated by oil on the patterned hydrophilic areas on a relatively more hydrophobic flat substrate. In our pioneer study, we created an array of 700-picoliter droplets. The randomly seeded E. coli cell number in each discrete droplet approaches single-cell levels. The total time needed for MOCCA fabrication was no more than 10 minutes. Compared to traditional micro-fabrication techniques, MOCCA dramatically lowers the cost and enhances the efficiency for the fabrication procedure, while producing a microscale array as in those made using traditional methods.