Method for rapid and large-scale generation of droplets and droplet libraries

A method of generating droplets, comprising:

• aspirating a first liquid into a lumen of a tube through an opening in the tube, wherein the tube is part of a piezo-electric droplet generator;
• positioning the opening over a receiving liquid;
• ejecting the first liquid from the opening to generate a first plurality of droplets that contacts the receiving liquid,
• wherein the first plurality of droplets and the second plurality of droplets remain discrete and 50% or more of the first plurality of droplets do not merge after contacting the receiving liquid;
• washing the tube with a washing liquid;
• aspirating a second liquid into the tube through the opening;
• positioning the opening over the receiving liquid;
• and
• ejecting the second liquid from the opening to generate a second plurality of droplets that contacts the receiving liquid thus creating a library comprised of the first plurality of droplets and the second plurality of droplets,
• wherein the second plurality of droplets remain discrete and 50% or more of the second plurality of droplets do not merge after contacting the receiving liquid.