The Science of Artificial Hands
Our hands are possibly our most versatile tool; we use them for almost every aspect of our daily lives and few of us could imagine surviving without them. For those unlucky enough to suffer from congenital hand malformations, or amputees as a result of disease or injury, this is even more clear. In the US, over 40,000 people have undergone hand or arm amputation, most commonly due to injury, cancer or vascular complications of diseases such as diabetes. Although limb loss may once have been a truly debilitating and lifetime loss, remarkable advances in artificial limb technology are making the outlook for amputees much better.
Scientists have made major breakthroughs in creating mechanical hands that are sufficiently dexterous to perform fine motor actions, and which can communicate directly with the brain to enable patients precise control over their new hand. The last decade has seen such innovations as the iLimb, which improved on previous models in terms of the range of gestures achievable, and more recently the SmartHand made initial strides into creating a robotic hand that could be controlled by the mind. The technology uses myoelectric linking to transmit electrical impulses from muscle fibres in the arm to the artificial hand which is able to interpret these into movements. This year, the latest in prosthetic hands was released; the BeBionic3 is a carbon-fibre hand with aluminium and alloy knuckles. Separate motors for each finger allow much finer motor control allowing increased strength and gripping capabilities.
Artificial hands need to interpret information from the brain and translate that into movement. But real hands are also sensory organs themselves, transmitting information about pressure, temperature and texture to the brain. Currently artificial hands do not provide this sensation, but researchers are developing artificial skin which may be able to mimic both the self-healing and sensitive properties of skin. Using a polymer formed of long, hydrogen-bonded chains of molecules, and flecked with nickel nanoparticles, researchers at Standford have creating a material that heals and feels.
New prosthetic hands are now good enough that for some patients with a lack of functionality in an intact hand, amputation and replacement with a high-tech prosthetic is the best option. Perhaps in just a few years time, brain-prosthesis interfacing technology can be combined with sensitive artificial skin to provide even greater control, precision, dexterity and ultimately quality of life to amputees.
Want to Know More?
- Tee, Wang, Allen & Bao (2012) An electrically and mechanically self-healing composite with pressure- and flexion-sensitive properties for electronic skin applications. Nature Nanotechnology
- Amputee Coalition
- BBC News (2011) Bionic hand for ‘elective amputation’ patient
- BeBionic 3