Nozzleless liquid droplet ejectors

A nozzleless droplet ejector for ejecting droplets of liquid from a surface of a liquid filled reservoir, said ejector comprising

• a planar surface acoustic wave transducer which is submerged at a predetermined depth in said reservoir;
• drive means coupled to said transducer for energizing said transducer to launch a cone of acoustic waves into said liquid at an angle selected to cause said acoustic waves to come to a focus of predetermined waist diameter approximately at the surface of said reservoir, whereby said focused acoustic waves impinge upon and acoustically excite liquid near the surface of said reservoir to an elevated energy level within a limited area determined by said waist diameter thereby enabling liquid droplets of predetermined diameter to be propelled from said reservoir on demand, and
• means for coupling asymmetrical acoustical energy into said reservoir for steering said focused acoustic waves in a plane generally parallel to the surface of said reservoir.

An array of nozzleless droplet ejectors for ejecting droplets of liquid from a liquid filled reservoir, said array comprising

• a generally planar piezoelectric substrate submerged at a predetermined depth in said reservoir,
• plural pairs of ring-like, multi-element, interdigitated electrodes deposited on said substrate on laterally displaced centers, whereby said electrode pairs and said substrate define a plurality of substantially independent surface acoustic wave transducers, and
• drive means coupled across said electrode pairs for exciting said transducers for launching respective acoustic beams into said liquid at an angle selected to cause each of said acoustic beams to come to focus approximately at the surface of said reservoir, with said focused acoustic beams being laterally displaced from each other.