Micro-machined nozzles

A method of fabricating a micro-machined nozzle, comprising the steps of:

• etching a first side of a silicon substrate to form a hole that extends partially through a thickness dimension of the substrate;
• and
• etching a second opposite side of the silicon substrate to form a nozzle orifice that communicates with the hole, wherein the nozzle orifice is serrated around its entire interior circumference with a plurality of ridges, the ridges having a first long radial length and a second short radial length, the lengths of the ridges alternating between the first and second lengths such that each short ridge is positioned between two longer ridges.

A micro-machined nozzle array, comprising:

• a silicon substrate etched on a first side of the silicon substrate to provide a plurality of holes that each extend partially through a thickness dimension of the substrate, etched on a second side of the silicon substrate to provide a plurality of nozzle orifices that each communicate with a corresponding hole, and further etched on the second side of the silicon substrate to provide a plurality of substantially cylindrical exterior walls that each surround a corresponding nozzle orifice, wherein each nozzle orifice is serrated around its entire interior circumference with a plurality of radially extending ridges and wherein the ridges have a first long radial length and a second short radial length, the lengths of the ridges alternating between the first and second lengths such that each short ridge is positioned between two longer ridges;
• and
• a nozzle holder attached to the silicon substrate that provides a liquid reservoir defining an interior chamber between the holder and the first side of the silicon substrate.