LIVERMORE — Once reserved for sci-fi heroes and far-fetched television shows, bionic arms that can communicate with the brain are under development at Lawrence Livermore Lab and five years away from human testing.

While a robotic arm conjures images of superhumans able to throw boulders like pillows, researchers are serious about recreating sensations that many take for granted: to feel the skin of a significant other, the texture of a fine linen or the cool water of a babbling brook. The arm, and its connection to the nervous system, would be nothing short of a miracle for thousands of veterans who have returned from war with missing limbs.

“It would be a life-changing event,” said Sat Pannu, director of the Center for Bioengineering at Lawrence Livermore Lab, one of eight teams nationwide working to develop the arm. “Quite literally, it would be a real biological replacement of their arm.”

Referred to by researchers as HAPTIX, short for Hand Proprioception and Touch Interfaces, the project is being funded by a $55 million, five-year U.S. Defense Department initiative.

The project will adapt advances made in a separate half-billion dollar investment by the Defense Advanced Research Projects Agency (DARPA), which has led to two types of advanced robotic arms, one by Segway inventor Dean Kamen’s company DEKA — the arm named “Luke” after Luke Skywalker — and another from Johns Hopkins University.

As profound as these prosthetics are, they have their limitations, researchers say. They aren’t yet capable of the fine controls necessary to perform complex functions, and most important, they can’t provide sensory feedback.

“They’re simply amazing machines, but without the intimate connection to the user, they’re just that; amazing machines that aren’t fully integrated into the body,” said Doug Weber, a DARPA project manager. “HAPTIX aims to bridge that gap.

“Once you start providing amputees with renewed sensation, some amazing things start to happen,” he said. “The experience has been hugely emotional. They talk about really feeling their hand again for the first time since their injury.”

HAPTIX aims to create a fully implantable system approved for human use by 2020. To get there, scientists will essentially need to learn a new language — translating nerve impulses into commands for the bionic hand, be it grasping an object, flexing a finger, or making a fist. It’s delicate data; an action as simple as gripping a glass must be precise — too much force, and the glass breaks. Even more challenging, researchers say, is sensory feedback, figuring out how to recreate the shape and pattern of signals to stimulate the nerves correctly.

Pannu’s group is developing tiny wireless “smart packages” to measure and decode the signals from the nervous system. Electrodes would attach to the major nerves in the upper arm and connect to an implanted device, while electronics the size of a watch battery would stimulate and record nerve activity. Another package would contain a battery and wireless system for sending signals back to the nervous system.

To replicate the richness of perceivable sensations, Pannu’s approach is to incorporate thin-film electrode arrays, devices one-tenth the width of the human hair that could potentially place hundreds of electrodes around each nerve. Tapping the peripheral nerves is not only less risky and easier than accessing the brain, but it also would allow users to perform complex actions without mental concentration, Pannu said.

“The goal of HAPTIX is to be able to measure signals from the user that can be used to control all of the motions of the prosthesis in a very natural and fluid way,” Weber said. “Instead of having to learn some arbitrary new set of motor skills, the person would just think about moving their hand the way they would normally do.”

The VA Palo Alto Medical Center is home to one of seven Regional Amputee Clinics in the nation, providing rehabilitation to many of the more than 1,500 soldiers who have come home from Iraq and Afghanistan as amputees. While lower limb prosthetics generally allow users to return to semi-normal functioning, upper limb prosthetics are a different story, says attending physician Dr. Molly Timmerman.

Many amputees struggle with traumatic brain injuries. Combined with the weight and difficulty of controlling conventional prosthetic arms, 30 to 50 percent of upper-extremity amputees decide they aren’t worth the hassle, she said.

“A lot of people ultimately don’t tolerate it. It tends to be very cognitively demanding because you have to use visual feedback,” Timmerman said. “Our patient population is unique, they’re really can-do people … but the truth comes out in the data of whether they’re using them or not, and a lot of them are not using (them).”

Pilot studies of nerve-prosthetic interfaces at Case Western and the University of Utah have been promising. Dozens of amputees have reported vivid sensations of touch from electrical stimulation, Weber said.

By the fourth year, researchers expect a finished product ready for human trials out of the Louis Stokes Cleveland VA Medical Center. The take-home trials would involve soldiers and civilians and occur in the project’s fifth year.

“Success in my mind is a device that works reliably and effectively and (has) our amputees tell us that they’re not going to give their test device back because they love it so much,” Weber said. “It’s going to feel like they have their hand back, and they’re not going to want to lose it again.”

Contact Jeremy Thomas at 925-847-2184. Follow him at Twitter.com/jet_bang.