Pimp my arm 

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Take the first two fingers of your hand. Bring them together; now pull them apart. Try to pick up something with those fingers -- no cheating with the opposable digit. Try to hang onto it. Some stuff you can easily manipulate; some stuff slips from your grasp. This is roughly what it's like to use an arm prosthesis.

The typical prosthesis has two basic parts: a socket, where the residual limb connects to a molded arm or leg; and a terminal device, a foot or hand, or in many cases, a hook.

While they may look conspicuous, hooks are usually more functional than sculpted hands. The biggest issue with hooks is how to open and close them. With a body-powered prosthesis, the wearer moves his or her shoulder to open or close the hook. The tension of the grip is controlled by rubber bands -- which break, snap, dry out and deteriorate over time. Want to change the degree of tension? Add or subtract bands. Myoelectric devices do the same thing using electronic muscle sensors to send the open and close signals, but the basic design of most prosthetics hasn't changed much in 50 years.

Like a lot of wearers, Kuniholm would love to have a device that regulated grip tension some better way. Surely somebody out there had improved on this particular mousetrap, he thought. Research turned up a device called a vector prehensor, invented by professors Larry Carlson at the University of Colorado at Boulder and Dan Frey at the Massachusetts Institute of Technology. It uses an adjustable dial to control the tension of an internal spring. It's not available for purchase, unfortunately, because it was never manufactured. But Carlson and Frey weren't the first ones to employ the concept. A prior art search turned up a 1954 German patent for a similar device, but that one never saw the light of day, either.

"A patent was issued, no product was ever made and it was basically forgotten about," Kuniholm says. "I'm convinced that there are lots of good ideas that remain hidden in the patent literature that deserve to be publicized and made more accessible."

Carlson and Frey have decided to contribute the design they developed to OPP, which will make the plans available under the public domain. If somebody else manages to make some money off their work, they don't mind, Kuniholm says.

"Somebody asked us early on, 'Aren't you concerned that somebody will steal your ideas?' And we said, 'That's the idea!' Nothing would make us happier than if a company that's already engaged in developing prosthetics devices -- that has marketing, distribution, sales support, engineering -- were to take our designs and modify them a little bit, make it appropriate to the portion of the market they were looking at, and then sell it. We would have had an idea that made it to the marketplace, and that would mean more options for prosthetic users, which is the point."

The market is good at producing better cell phones and MP3 players -- things millions of affluent people are willing to pay for. Innovation in those areas is rapid. But the market isn't very good at innovating when the products won't sell by the millions, or when customers don't have the money to pay.

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• Derek Anderson

Bob Malkin is a professor of engineering at Duke and director of the Duke chapter of Engineering World Health. He oversees a nonprofit business plan competition called CUREs (Competition for Underserved and Resource-poor Economies), now in its second year. Biomedical engineering students design inexpensive devices to serve a need in the developing world while business and management students devise a nonprofit business plan to deploy this new technology. Tackle's Messer is a judge for the contest, and through it has enlisted Tackle to further develop last year's winning entry, a light therapy device to cure babies born with jaundice. The blue-spectrum light breaks down a substance called biliruben so that the body can process it. It's a simple process, but the cost of devices used in Western hospitals is well out of reach of most hospitals in the developing world. This one is cheap and easy to repair. Messer and his colleagues took on the task of improving the design, and they plan to assemble a set of prototypes this winter that will be tested at Duke Hospital and eventually in the field.

There's another important component to the CUREs competition designed to help the developing world: All designs go into the public domain.

"There is an intellectual basis and a historical basis for this," Malkin says of the project's intellectual property stance. "When we were the developing world, around 1870 or so, we regularly violated intellectual property rights." Today, the West rigorously enforces intellectual property laws, forcing developing nations to pay licensing fees or buy devices they can't afford. "By enforcing those sorts of rules, we're kicking away the ladder, removing a rung of the ladder that we're not allowing the developing world to use. The essential rung for development is intellectual property, and denying them that is denying them the very tools that we used when we were developing."