Principle. By spraying at 2 - 0.2 mm (0.08 - 0.008 inch) above a substrate, spots of 1.5 - 0.15 mm (0.06 - 0.006 inch) in diameter are obtained using a capillary-OD of 150 micron. The charged droplets are attracted to the substrate and form a thin layer.

Dotting in wells printed in PMMA substrate. Wells are 300 micron in width and the dot width is approximately 200 micron. In-between dotting we forced the spraying to stop by rapidly increasing the distance to the substrate from 350 micron to 450 micron.

Dotting onto silicon nitride. Reproducible dotting is achieved into wells of 400 micron in width and 50 micron deep. Flowrate is 200 pL/s and the spraying distance is 400 micron.

Spraying of lines onto polymethyl methacrylate. PMMA is sputter-coated with gold to achieve stable spraying of liquid lines. The line width is approximately 100 micron at a flow rate of 300 pL/s and a spraying distance of 250 micron.