Uniform Nanoliter Solute Deposition by the Control of Droplet Profile During Evaporation with Microwell

It is important but difficult to control the uniformity of solute deposition from a nanoliter droplet. The uniformity of solute deposition for a droplet in a nanoliter well is controlled by evaporation process. This paper proposes a method for uniform solute deposition from droplet evaporation confined by rib structures with specific surface properties, and the dynamic process is conducted experimentally and is analyzed in detail. Hydrophilic degree on the well surface is critical for controlling the film uniformity in the dynamic evaporation process, in particular around the rib of well. Experimental result indicates that the higher hydrophobicty (contact angle above 90°) on well surface yields flatter film profile during droplet evaporation inside a well, thus promotes a more uniform solute deposition.