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DARPA

Mind-controlled prosthetics without brain surgery

Mind-reading is powerful stuff, but what about hand-reading? Intricate, three-dimensional hand motions have been "read" from the brain using nothing but scalp electrodes. The achievement brings closer the prospect of thought-controlled prosthetics that do not require brain surgery.

Electroencephalography (EEG), which measures electrical activity through the scalp, was previously considered too insensitive to relay the neural activity involved in complex movements of the hands. Nevertheless, Trent Bradberry and colleagues at the University of Maryland, College Park, thought the idea worth investigating.

The team used EEG to measure the brain activity of five volunteers as they moved their hands in three dimensions, and also recorded the movement detected by motion sensors attached to the volunteers' hands. They then correlated the two sets of readings to create a mathematical model that converts one into the other.

In additional trials, this model allowed Bradberry's team to use the EEG readings to accurately monitor the speed and position of each participant's hand in three dimensions.

If EEG can, contrary to past expectation, be used to monitor complex hand movements, it might also be used to control a prosthetic arm, Bradberry suggests. EEG is less invasive and less expensive than the implanted electrodes, which have previously been used to control robotic arms and computer cursors by thought alone, he says.

Giving Prosthetic Limbs The Sense Of Touch

When I was a child I dreamt about one day becoming a biomedical engineer. And, somewhere in my mother's attic lies the remnants of that dream in the form of school papers and crayon drawings of the limbs, heads, and torsos that I one day hoped to design, engineer, and implant on human beings and animals. Aside from making me the creepiest kid in the neighborhood this also provided me with a special way of thinking about the interconnections and relationships between machines and people. That dream ultimately evaporated in college when I chose to start monetizing my software development hobby instead of completing my inorganic chemistry studies.

Today however actual biomedical engineers have come one step close to the giving a sense of touch to prosthetics for humans. Existing robotic prostheses have limited motor control, provide no sensory feedback and can be uncomfortable to wear. In an effort to make a prosthesis that moves like a normal hand, researchers at the University of Michigan (U-M) have bioengineered a scaffold that is placed over severed nerve endings like a sleeve and could improve the function of prosthetic hands and possibly restore the sense of touch for injured patients.


To overcome the limitations of existing prostheses, the U-M researchers realized a better nerve interface was needed to control the upper extremity prostheses. So they created what they called an “artificial neuromuscular junction” composed of muscle cells and a nano-sized polymer placed on a biological scaffold. Neuromuscular junctions are the body's own nerve-muscle connections that enable the brain to control muscle movement.

When a hand is amputated, the nerve endings in the arm continue to sprout branches, growing a mass of nerve fibers that send flawed signals back to the brain. The bioengineered scaffold was placed over the severed nerve endings like a sleeve. The muscle cells on the scaffold and in the body bonded and the body's native nerve sprouts fed electrical impulses into the tissue, creating a stable nerve-muscle connection.

In laboratory rats, the bioengineered interface relayed both motor and sensory electrical impulses and created a target for the nerve endings to grow properly. This indicates that the interface may not only improve fine motor control of prostheses, but can also relay sensory perceptions such as touch and temperature back to the brain. Laboratory rats with the interface responded to tickling of feet with appropriate motor signals to move the limb.


The research project, which was funded by the Department of Defense, arose from a need for better prosthetic devices for troops wounded in Afghanistan and Iraq. The DoD and the Army have already provided $4.5 million in grants to support the research. Meanwhile, the University of Michigan research team has submitted a proposal to the Defense Advance Research Project Agency (DARPA) to begin testing the bioengineered interface in humans in three years.

SHAPE SHIFTING ROBOTS

I've written here about robots that use a variety of ways to get around, from caterpillar treads, to wheels, legs, wings and even combustion-driven pistons. But the title of the most interesting method of robot propulsion I’ve come across has to go to the shape-shifting ChemBot from iRobot. The ChemBot, which looks more like the Blob than most people’s preconceived ideas of what a robot should be, moves around by changing its shape in a process its developers call, “jamming skin enabled locomotion,” or JaSEL.

JaSEL is a physical process whereby a material is made to transition from a liquid-like to a solid-like state by increasing its density. The ChemBot achieves this process thanks to its hyper-elastic skin composed of multiple cellular compartments. These compartments are filled with air and loosely-packed particles. When the air is removed, the decrease in pressure constricts the skin and the particles shift slightly to fill the void left by the air, resulting in the solidification of the compartment.

Beneath the ChemBot's jammable skin is an incompressible fluid and an actuator that can vary its volume. Unjamming various compartments of the ChemBot’s skin and inflating the interior actuator causes the Chembot's skin to stretch, changing the shape of the robot. It is this method of controlled inflation that allows the ChemBot to roll around.

It should come as no surprise that the ChemBot is the result of US$3.3 million award from the Defense Advanced Research Projects Agency (DARPA) and the U.S. Army Research Office given to iRobot to “develop a soft, flexible, mobile robot that can identify and maneuver through openings smaller than its actual structural dimensions to perform Department of Defense (DoD) tasks within complex and highly cluttered environments.”

The disturbing video below of the ChemBot in action is as it appeared about a year ago, so it’s anyone’s guess how much more creepy the ChemBot is now. Apparently, it has a slightly different design and its creators are working towards including sensors on its body and even connecting multiple ChemBots.