Human Eye Inspires Clog-Free Ink Jet Printer

Making Homemade Guns On a 3-D Printer Becomes Real, So Engineering Expert Suggests Stronger Laws On Gunpowder

Feb. 11, 2013 — With controversy swirling over gun-sale background checks, limiting the size of weapon magazines and retaining Second Amendment rights, the problem of making homemade guns with 3-D printers has become a matter of public concern.

Laws mean little if a determined criminal or a hobbyist teen wants to make plastic guns or extra-high capacity magazines, says Hod Lipson, Cornell University professor of engineering and a pioneer in 3-D printing.

"With a homemade 3-D printer, you can print a gun using ABS plastic, the same material that LEGOS are made out of. You can even use nylon, and that's pretty tough," he says. "You won't be able to make a sniper rifle with a 3-D printer and it won't shoot 10 rounds a second, but the gun you can make could be dangerous. And a high-capacity magazine is nothing more than a strong plastic box with a spring. It's trivial to print."

Lipson and co-author Melba Kurman just published a new book, "Fabricated: The promise and peril of a machine that can make (almost) anything." (Wiley, 2013.) The book includes a chapter on "3-D printing and the law," which addresses the legal and ethical challenges raised by 3-D printed firearms. The book also explores 3-D printing's impact on consumer safety, intellectual property, and ethics.

As Lipson and Kurman detail, three-dimensional printers are intended to do the world good. In industry, 3-D printers can make hard-to-find spare parts and complex new devices. Researchers are developing techniques to 3-D print tailored and personalized body parts like heart valves. 3-D printers can even make food.

Lipson explains that on the Internet, there are blueprints and designs available to 3-D print guns. As an engineer, he's seen dubious rogue designs online. "Some designs are not safe," he says. "More than criminals, I am worried about innocent kids making guns and injuring themselves. What happens if the design is faulty or if the plastic was printed at the wrong temperature, rendering the gun weak? When fired, it could blow up in its user's face. All kinds of parameters go into making 3-D objects and when you introduce an explosive such as gunpowder, that's when things can go wrong," Lipson says. The small footprint of new personal-scale manufacturing systems also makes it easier to fabricate firearms more discreetly than before.

Lipson agrees that a more effective gun control solution worth exploring might impose legal limitations on gunpowder rather than gun parts and accessories such as magazines.

Says Lipson: "If I were talking to lawmakers, I would encourage them to address the most basic part of a firearm -- the energy source. You must have gunpowder to fire a weapon. The law could regulate the explosives. To fire a bullet, you need high-energy propellant like gunpowder. After all, 3-D printed and arbitrarily shaped plastic firearms are going to be increasingly hard to detect using traditional screening techniques. A high-capacity magazine might look like something else. It may be more effective to control the gunpowder."

Human Eye Inspires Clog-Free Ink Jet Printer

Clogged printer nozzles waste time and money while reducing print quality. University of Missouri engineers recently invented a clog-preventing nozzle cover by mimicking the human eye.

"The nozzle cover we invented was inspired by the human eye," said Jae Wan Kwon, associate professor in the College of Engineering. "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 invention 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 off the eye. On the surface of the human eye, eyelids spread the film of oil over the layer of tears. However, at the tiny scale of the ink jet nozzle, mechanical shutters like eyelids would not work, as they would be stuck in place by surface tension. Instead, the droplet of oil for the nozzle is easily moved in and out of place by an electric field.

Kwon said this invention could make home and office printers less wasteful. To clear a clogged nozzle in most ink jet printers, a burst of fresh ink breaks through the crust of dried ink which forms if the machine isn't used constantly. Over time this cleaning operation can waste a large amount of expensive ink. Kwon's invention eliminates the need to waste that squirt of ink.

"Other printing devices use similar mechanisms to ink jet printers," Kwon said. "Adapting the clog-free nozzle to these machines could save businesses and researchers thousands of dollars in wasted materials. For example, biological tissue printers, which may someday be capable of fabricating replacement organs, squirt out living cells to form biological structures. Those cells are so expensive that researchers often find it cheaper to replace the nozzles rather than waste the cells. Clog-free nozzles would eliminate the costly replacements."

Similarly, rapid prototyping systems used by engineers and product designers emit streams of liquid plastic through nozzles like those on an inkjet printer. The thick, sticky liquid used in the devices can make it necessary to replace the whole nozzle when they become clogged. These specialty printer parts can cost thousands of dollars.

MU engineering doctoral student Riberet Almieda worked with Kwon on the oil droplet nozzle cover. A paper documenting the discovery was published in the Journal of Microelectromechanical Systems

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