Ultra-high resolution inkjet technique prints drops capable of trapping light

Inkjet printing, familiar from millions of desktop printers, is the basis for many new techniques in electronics and biotechnology, using the technology's ability to accurately place small droplets of material to make structures from conducting or semiconductor materials or even living cells. The Cambridge team, from the University's Cavendish laboratory and Hitachi's laboratory in the city, have modified this technology so that it can print dots of ink with optoelectronic properties that can trap and harness light.

The key to the technique, which the team describes in Advanced Materials, is in reducing the size of the droplets to the scale of the wavelength of light. The co-first authors of the paper, Vincenzo Pecunia, a visiting researcher at the Cavendish laboratory, and Hitachi researcher Frederic Brossard, discovered that a new type of printer developed by Pecunia was capable of this resolution.

The printer dispenses ink by a method known as electrohydrodynamic jetting. "Most inkjet printers push the ink through the nozzle by heating or applying pressure, producing ink droplets about the size of the diameter of a human hair," Pecunia explained. The novel printer instead applies a voltage to the ink, forcing it through a much smaller nozzle and producing droplets 10 to a hundred times smaller than those of conventional printers; the droplets have a volume in the femtolitre range, ejected from a nozzle about a micron across.