Physics of Ink-jet Printing

Ink-jet is a dot-matrix printing technology in which the drops of ink are jetted through a small orifice to a specific position on a substrate. The mechanism by which a liquid stream breaks up into droplets was described by Lord Rayleigh in 1878[1]. There are two qualitatively different ink-jet printing methods drop on demand (DOD) and continuous ink-jet printing (CIJ). The underlying mechanism for CIJ printing is breaking a continuous jet into droplets and was ”discovered” first, with first patent of a working practical Rayleigh break-up ink-jet device filed in 1951[5]. The DOD printer, in which we actually ”squirt” a jet of liquid that joins in a drop under surface tension driven forces, was not made until 1977[5]. In this seminar I will try to outline basic governing physics of ink-jet process, current challenges and possible future applications utilizing this technology.