Evaporation of a picoliter droplet on a wetted substrate at reduced pressure

The results of theoretical and experimental investigation of the evaporation of picoliter water droplets on a substrate at reduced pressure (20–80 Torr) have been given. The substrate temperature varied in the range 25–40°C. The calculations have been carried out in a free-molecular approximation. It has been shown that the evaporation time sharply decreases if the average droplet height is less than 10 μm and is a few milliseconds for a 5-μm-high droplet. It has been experimentally and theoretically shown that for droplets higher than 10 μm, the evaporation time is a few seconds in the investigated pressure range.