Liquid-based printing technigques are typically limited to forming jets from orifice diameters of approximately 50 microns or greater. Below the 50 micron limit nozzle clogging becomes problematic, and precludes practical application of liquid jetting to stable printing. The IDS technology produces sub-50 micron traces, and circumvents the issue of clogging using a coaxial flow consisting of a sacrificial sheath fluid and a core ink. The coaxial distribution reduces the effective diameter of the orifice, and protects the inner walls of the nozzle orifice from clogging. An annular liquid sheath fluid propagating within a flow cell focuses an inner sample fluid to produce a continuous liquid filament that is deposited onto a substrate. The flows are incompressible, and driven by a pressure source or syringe pump.
Hydrodynamic focusing is accomplished when a sheath fluid surrounds a core fluid and moves through a flow cell at a higher flow rate than the core fluid. The increased cell volume occupied by the sheath fluid results in a reduction of the volume occupied by the core fluid (ink), and leads to focusing of the ink stream. Analytical, computational, and experimental characterizations of the hydrodynamic focusing effect of the Liquid Jet cell show good agreement, and yield focused ink flows as small as 10 microns.
Liquid Jet line widths from 10 to 1000 microns are attainable at print speeds of greater than 100 mm/s.