Unlike conventional ink-jet printers, which use heat or mechanical vibrations to launch liquid droplets through a nozzle, e-jet printing uses electric fields to pull the fluid out. Although the concept of electric-field induced flow is not new, the way the research team has exploited this phenomenon with nanoscale nozzles and precision control of electric fields to achieve unprecedented levels of resolution is an important advance.
The researchers e-jet printing head consists of a gold-coated microcapillary nozzle (with a diameter as small as 300 nanometers) mounted on a computer-controlled mechanical support. An organic, Teflon-like coating on the gold ensures the ink flows cleanly out the nozzle toward the target. Tiny droplets of ink eject onto a moving substrate to produce printed patterns. Lines with widths as narrow as 700 nanometers, and dots as small as 250 nanometers, can be achieved in this fashion.
As a demonstration of electronic device fabrication by e-jet printing, thin-film transistors that use aligned arrays of single-walled carbon nanotubes as the semiconductor and e-jet-printed source and drain electrodes were printed on flexible plastic substrates. The transistors were fully operational, with properties comparable to similar devices fabricated with conventional photolithographic methods.
The team also demonstrated that e-jet printing could be extended to a wide variety of functional organic and inorganic inks, including suspensions of solid objects (such as nanoscale silicon rods) with resolutions again extending to the submicron range.
Because the nozzles are routed directly to reservoirs of inks, e-jet printing has the capability to deliver large volumes of ink to a surface, and offers the ability to
|Contact: James E. Kloeppel|
University of Illinois at Urbana-Champaign