Artificial limbs and prosthetics have come a long way from the 1963 CO2 gas-powered artificial arms exhibited at the Wellcome Trust in 2012.
In the 21st century, the Pentagon’s research division, Darpa, has been at the cutting edge of prosthetics development, in no small part due to the wars in Iraq and Afghanistan.
Darpa’s touch-sensitive artificial prosthetic, described in a statement on 30 May, interfaces directly with the wearer’s neural system and shows just how far we’ve come.
Unlike direct brain neural interfaces, the prosthetic connects with nerves in the patient’s limb, therefore requiring less serious and less risky surgery.
It doesn’t require any visual information to operate, allowing the wearer to control it without maintaining visual contact. This makes “blind” tasks, like rummaging through a bag, much easier.
A flat interface nerve electrode (Fine) provides direct sensory feedback to the patient. Fine is a way of hacking into the body’s nervous system by flattening a nerve. This exposes more of the nerve to electrical contact, making it easier to interface with it. Researchers at Case Western Reserve University, involved with the touch-sensitive prosthetic, previously used Fine to reactivate paralysed limbs.
In the video, the wearer of the prosthetic hand is able to identify which finger researchers at Case Western Reserve University are touching without looking.
Groups across the world are engaged in similar research, including a team at the École Polytechnique Fédérale de Lausanne in France which announced in February that it would be trialling a touch-sensitive prosthetic this year.
Startlingly natural prosthetic movement, including bouncing and catching a tennis ball with a fully artificial arm and hand, is also described in Darpa’s 30 May statement.
Using a type of neural connection called targeted muscle re-innervation (TMR), researchers at the Rehabilitation Institute of Chicago (RIC) were able to achieve simultaneous control of the shoulder, elbow and wrist.
TMR involves re-wiring nerves from amputated limbs so that existing muscles, like those in the shoulder, for example, can be used to control the prosthetic arm.
Last year, Zac Vawter climbed the 442m Willis Tower in Chicago with an artificial leg that used TMR. He was fundraising for the RIC.
This video shows former Army Staff Sgt Glen Lehman, injured in Iraq, demonstrating the full range of fluid motions enabled by the TMR prosthetic arm.