Evaporation evolution of volatile liquid droplets in nanoliter well array

It is well known that a solute usually carries out a non-uniform deposition when deposited from an evaporating droplet. The evaporation behavior of volatile micro droplets with nanoliter volume has been modeled and experimented in detail for insight into this phenomenon. The results show that there are two phases existing during the whole evaporation of water droplets: (I) constant baseline region in first 50% of total time; (II) constant contact-angle region in the last 50% of total time. The average volume rate of evaporation is 1.66 nl/s for the initial baseline of 2.27 mm during 2160 sec. Furthermore, the evaporation experiment performed in circular nanoliter wells, of height 65 μm and diameters ranging from 240 μm to 1270 μm, demonstrated that the moving speeds of thin water films during rupture ranged from 20 μm/s to 25 μm/s; for larger circular wells, there was a higher initial broken percentage. This study may be beneficial to the design of microstructures for uniform solute deposition from the evaporation of liquid droplets.