What’s the News: Engineers and patients dream of mechanical prosthetic limbs that can talk and listen to the brain, moving in response to thought and sending back sensory information. For that dream to become reality, electrodes from the prosthetic have to connect with nearby nerve cells—a tricky proposition, given that nerve cells in an amputated limb won’t grow without proper structural support. A new tubular scaffold, described in detail by Technology Review, has tiny grooves that fit bundles of nerve cells, which could provide the support nerves need to interface with a mechanical limb better than current designs.

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For DARPA, the secretive military research agency, it’s not enough for a prosthetic limb to simply resemble a normal one, or for a patient to be able to move it through some remote control. DARPA-backed engineers are attempting to build a system in which peripheral nerves would be reattached to artificial limbs, which could send signals to a brain sensor that could reply. This would be a vast improvement over prosthetics that require conscious directives, and could turn a prosthetic into something that responds the way an ordinary limb would.

Darpa’s after a prosthetic that can record motor-sensory signals right from peripheral nerves (those that are severed when a limb is lost) and then transmit responding feedback signals from the brain. That means an incredibly sensitive platform, “capable of detecting sufficiently strong motor-control signals and distinguishing them from sensory signals and other confounding signals,” in a region packed tightly with nerves. Once signals are detected, they’ll be decoded by algorithms and transmitted to the brain, where a user’s intended movements would be recoded and transmitted back to the prosthetic. [Wired.com]

According to the team behind the system at Johns Hopkins University’s Applied Physics Laboratory, tests on monkeys have shown that the primates have remarkable success controlling a prosthesis through a cortical chip implanted in their brains, and researchers have undertaken some human tests. What remains to be seen, though, is how much dexterity people can get through this process.

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It’s big, it’s loud, it’s Iron Man 2, and it opens today.

Like a lot of summer blockbusters, this sequel stretches the laws of physics and the capabilities of modern technology. But, admirably, a lot of the tech in Iron Man 2 is grounded in fact.

Spoiler Alert! Read on at your own risk.

Palladium and particle colliders

Being Iron Man is killing Tony Stark. As this sequel begins, the palladium core that powers the suit and keeps Stark alive is raising toxicity levels in his bloodstream to alarming highs. It’s not hard to see why Iron Man would try palladium—the now-infamous cold fusion experiments that created a storm of hype in 1989 relied on the metal. And it’s true that palladium does have some toxicity, though it’s been used in alloys for dentistry and jewelry-making.

Having exhausted the known elements in the search for a better power source, Stark, ever the DIY enthusiast, builds a particle collider in his workshop. This is actually not crazy: Physicist Todd Satogata of Brookhaven National Lab says you can build tiny particle colliders; even whiz-kid teenagers do it.

Powering the accelerator, however, might be an issue. 2.5 miles long, Brookhaven’s superconducting collider needs 10 to 15 megawatts of power—enough for 10,000 or 15,000 homes. “For Stark to run his accelerator, he’s gotta make a deal with his power company or he’s gotta have some sort of serious power plant in his backyard,” Satogata says [Popular Mechanics].

In addition, Stark doesn’t appear to have the magnets needed to focus a beam as tightly as he does in the film, where it shreds his shop before he gets it focused in the right place. And, as we covered with the recent discovery of element 117, the ultra-heavy lab-created elements that Stark  could have created in his accelerator don’t last long. However, back in 1994 when only 106 elements dotted the periodic table, DISCOVER discussed the idea some physicists have of an “island of stability” where elements we’ve yet to discover/create might be able to exist in a stable way. Perhaps Tony found it.

The guts of the suit

After a long quest, the U.S. military gets its hands on Stark’s most magnificent piece of technology, the Iron Man suit. What they saw when they looked inside was the work of special effect wiz Clark Schaffer.

The silvery suit, originally seen in the first “Iron Man,” is shown again in the new movie in an “autopsy” scene in which the government begins tearing it apart to see how it works. “[The filmmakers] wanted it to look like what you see under the skin of a jet,” said Schaffer, who, along with friend and modeler Randy Cooper, worked on the suit in Los Angeles for six weeks. “There’s an aesthetic to it. I try to make it look as functional and practical as possible but also something that has beauty to it. That was my baby” [Salt Lake Tribune].

But how might the Iron Man suit be able to stand up to the punishment Stark continually receives? Tech News Daily proposes that he took advantage of something scientists are developing now: carbon nanotube foam with great cushioning power.

Plasma weaponry

Iron Man’s nemesis in this second installment is Ivan Vanko, played by the villainous and murky Mickey Rourke, who you might have seen in previews stalking around a racetrack with seemingly electrified prostheses attached to his arms. The explanation in the film is hand-waved a bit, but it seems Vanko’s weapons rely on plasma.

Scientists actually are developing weapons based on plasma, such as the StunStrike, which essentially fires a bolt of lightning, creating an electrical charge through a stream of plasma. Researchers have recently even created what appears to be ball lightning in microwave ovens, which Iron Man’s “repulsor blasts” resemble [Tech News Daily].

Drones and hacking

Vanko isn’t happy with just amazing plasma tentacles, though. Working for Stark’s rival military-industrialist Justin Hammer (Sam Rockwell), he develops a horde of ghastly humanoid drones for each branch of the military. That, of course, is straight out of science fact—our military relies increasing on robots, be they unmanned aerial vehicles, bots on the ground that investigate roadside bombs, or even unmanned subs currently under development.

He’s a hacker, too, seizing control of an Iron Man suit worn by Don Cheadle as Stark sidekick James Rhodes. As DISCOVER covered in December, that’s a real-life worry, too. Hackers figured out how to steal the video feeds from our Predator drones because of an encryption lapse at one step in the process.

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If  you read this blog last week, you might have seen us cover a study suggesting that South African sprinter Oscar Pistorius ought to be allowed to compete in the same track and field events as everyone else because his prosthetic legs confer no advantage over a sprinter with biological legs. But if you saw a study cited by the Associated Press and many other publications yesterday, you might think that Pistorius would soon be banned from competitions, because his “blades” let him swing his legs far faster than even the world’s fastest man, Usain Bolt. So what the heck is going on?

The AP’s study isn’t actually a “study,” per se. Rather, what the Journal of Applied Physiology published was a point-counterpoint (pdf), now freely available for anyone to read. In in, Peter Weyand and Matthew Bundle argue that Pistorius’ prosthetics are a huge advantage, particularly in what matters most: how fast he can move his legs. Weyand and Bundle say that the lightweight blades allow Pistorius “to reposition his limbs 15.7 percent more rapidly than five of the most recent former world-record holders in the 100-meter dash” [AP].

There is, however, a counterpoint to this argument in the journal piece that yesterday’s news reports neglected, coauthored by Alena Grabowski of the MIT Media Lab (who led the research on Pistorius’ blades that 80beats covered last week). Her team has found that the limiting factor determining an athlete’s top speed was how hard the foot or prosthesis hit the ground. Their study showed this “ground force” was around 9% lower in the prosthetic limb versus the unaffected leg [The Guardian]. Grabowski’s research focused on professional runners with only one prosthetic leg.

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South African sprinter Oscar Pistorius raised a ruckus last summer when the he wanted to qualify for the Beijing Olympics, thanks to the J-shaped carbon fiber blades that the double-amputee uses to run. Pistorius didn’t get to run in last summer’s games, but now an MIT team has released a study declaring that he doesn’t have an unfair advantage. Rather, the researchers found quite the opposite: Running blades for amputees, even made with today’s best materials, can’t compete with the legs that humans have evolved.

Pistorius has long argued that he should be allowed to compete alongside able-bodied athletes in races, but athletics authorities banned him from doing so in last year’s Olympic games, claiming that his blades gave him an unfair advantage over able-bodied athletes [The Guardian]. The MIT Media lab team led by Alena Grabowski helped to reverse his racing ban before turning its attention this year to the general question of whether blades or legs are better.

The team concocted a clever solution to the problem of testing this question. The study participants were six elite sprinters who had one intact leg and one leg that had been amputated below the knee. Researchers decided to study these types of amputees because they could compare their affected leg to their unaffected leg [Los Angeles Times].

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When 3-year-old Mark Blinder developed pain in his right arm, doctors diagnosed him with Ewing’s sarcoma, a rare bone tumor. Chemotherapy wasn’t working and radiation would have destroyed the growth plates in his bones. So instead of amputating the arm, doctors tried an experimental approach–implanting an artificial, expandable bone made of titanium and cobalt chrome, designed specifically for Mark. The bone, produced by the company Biomet Inc., is small enough to fit inside the 3-year-old’s arm, but should be sturdy enough to last his entire life.  Most artificial bones are used to replace only part of a bone, so they are glued securely to remaining bone. In Mark’s case, the entire humerus was being removed, so the prosthetic had to be attached to soft tissue [Los Angeles Times].

To install the bone, doctors first had to remove the tumor by carving out the fat around it, a process one of the doctor’s likened to carving out a peach pit without ever touching the pit. The surgery was a success but Mark, who is now 4 years old, underwent chemotherapy as a precaution. Mark is gradually relearning how to use his arm. He’s moving his wrist and fingers, can pick up small objects, and is receiving physiotherapy to rebuild strength and flexibility in the elbow and shoulder. He won’t ever regain full function in those joints, but he is using the arm more each day, his mother said [Los Angeles Times]. He will have to undergo three or four minor surgeries over the years so doctors can extend the prosthetic bone as he grows–but since the only other option open to Mark was amputating his arm completely, he probably won’t complain.

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Image: iStockphoto

This can only lead to a summer blockbuster. Researchers implanted tiny electrodes in two monkeys’ brains, allowing them to move robotic arms with their thoughts.

To motivate the monkeys to perform, they were encouraged to feed themselves marshmallows and pieces of fruit with the robotic arms, which had joints and “grippers” that roughly replicated fingers. According to the research team’s report in Nature [subscription required], the arms’ movements were fluid and natural, and the monkeys continuously adjusted the speed and direction of their robotic limbs.

While the technology isn’t yet ready for human testing, scientists are hopeful that it can eventually be applied to prosthetic limbs for people with spinal cord injuries, strokes, and other paralyzing conditions.

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