Need a H.A.N.D.?

    The future of prosthetics is encouraging.  There is a new prosthetic arm, “Proto 1,” which provides sensory feedback and has eight degrees of freedom - much greater control than present in today’s prostheses.  It relies on a Targeted Muscle Reinnervation technique (TMR), pioneered by Dr. Todd Kuiken.  It involves the transfer of residual nerves from the amputated arm to unused muscle regions close to the injury, like the chest.  Proto 1 is able to reposition the thumb to make many different grips that is very useful for many common tasks.  It can also bend at the elbow, rotate at the shoulder and wrist, and clench and unclench its fist.[3][4]
    There are already prototypes where neural controls allow people to move prostheses through thoughts.  These were first tested on monkeys where microelectrodes implanted in the primary motor cortex enabled them to use neural activity to control a prosthetic arm.[1]
    DARPA has developed a second thought controlled, mechanical prototype arm called “Proto 2.”   The arm is complete with a hand and fingers, which can perform 25 of the 30 joint motions that a regular arm can.  Scientists are testing sensory feedback from Injectable MyoElectric Sensors, injectable or surgically implanted devices that can measure muscle activity rather than having to depend on surface electrodes.[3][4] 
    A second program of DARPA’s is led by the Applied Physics Laboratory of John Hopkins University and involves technology which will allow the next generation of prosthetics to feel and manipulate objects naturally.  Another program led by Oakridge National Laboratory involves a new technology called mesofluidics. This technology may allow prosthetic fingers, thumbs, wrists, elbows, and shoulder joints to work as well as any natural limb by using 1 inch high pumps driven by tiny motors that compress and displace mineral oil or other fluids. A prototype finger that has 20 pounds of pinch force is currently being developed.[9]
    Work is being done on an artificial skin which can measure force as small as 0.1 Newtons.  It will be made of polyimide, a rubbery polymer with tiny carbon nanotubes embedded in it.  It is flexible, lightweight, and can generate electricity in response to pressure. The nanotubes can also conduct heat from the surface to temperature sensors in the polymer.  By redirecting the nerves in the arm to the chest muscles, the patients can sense touch, temperature, and pain on the chest as if it were on the hand.[10]
    There is a prototype prosthetic exoskeleton called, “Robot Suit Hybrid Assistive Limb,” designed by a company called CYBERDYNE, Inc.  The suit they have created increases strength, keeps the body active, and works as a whole prosthetic limb.  This suit, unlike those exampled in movies is sleek and less clunky, but still has all the same functions. The next step is to design a prosthetic exoskeleton using nanotechnology so that motors, pumps, and sensors are not protruding.[2][15]
    These prototypes are going to be the future building blocks for newer prostheses. There are many advances that must be accomplished to reach the goal of a truly, natural bionic arm. The technology to shrink the pumps, motors, sensors, and batteries needs to improve so that they do not weigh down the prostheses and make them unwieldy.  Motors need to be more efficient.  An artificial skin that functions wholly like natural skin is on the horizon. And most importantly the cost of nanotechnology needs to come down to make the newer prostheses economical.  Hopefully, we can lend a H.A.N.D.