Clog-free print nozzle mimics human eye

U.S. researchers say they've looked to the human eye for inspiration in designing a clog-free ink jet printer cartridge. University of Missouri engineers addressing the problem of clogged printer nozzles that waste time and money while reducing print quality have invented a new nozzle cover, a university release reported Monday. "The nozzle cover we invented was inspired by the human eye," engineering Professor Jae Wan Kwon, said. "The eye and an ink jet nozzle have a common problem: they must not be allowed to dry while, simultaneously, they must open. We used biomimicry, the imitation of nature, to solve human problems." Kwon's solution uses a droplet of silicone oil to cover the opening of the nozzle when not in use, similar to the film of oil that keeps a thin layer of tears from evaporating from the eye. In the human eye, eyelids spread the film of oil over the layer of tears during blinking. However, at the tiny scale of the ink jet nozzle, mechanical shutters "blinking" like eyelids would not work, as they would be stuck in place by surface tension. Instead, the droplet of oil for the nozzle is moved in and out of place by an electric field, the researchers said. In most ink jet printers, a burst of fresh ink must break through the crust of dried ink that forms if the machine isn't used regularly. This cleaning operation can waste a large amount of expensive ink over time, a waste Kwon's invention eliminates, the release said.