The incidence of
limb loss due to road accidents, and unsafe handling of machinery
is fairly high in India. Loss of the hand may be below the wrist,
the forearm, or in the upper arm; a loss at the shoulder results
in the greatest loss of function of the hand. An 'artificial hand'
can help restore a measure of normalcy to the injured. One of the
options for obtaining a man-made replacement for a lost hand is an
internally-powered motorized hand that can perform finger-like
pincer movements. The control of such a hand is usually achieved
by bioelectric signals picked up from muscles in the residual
limb. The costs of such imported motorized hands, however, are
prohibitive - it can be more than Rs. 3.00 lakhs.
With
funding from the Ministry of Social Justice and Empowerment
(1999), a team of three researchers from IITB and the Christian
Medical College (CMC), Vellore, have developed the first
successful, indigenous, motorized artificial hand that would cost
less than Rs 10,000. The motorized hand has several user-friendly
features including myoelectric and whistle controllers. A single
motor helps the co-ordinated movement of the fingers and thumb,
while another motor turns the hand at the forearm.
The
motors are operated by switches placed in the socket of the
artificial hand. The bulging of the muscles and the slight
movement in the residual limb of the amputee are used to control
these switches. Apart from its lower cost, the advantage that the
indigenously developed product has over imported ones is that it
works better in humid climates.
Following
preliminary tests at the All India Institute for Physical Medicine
and Rehabilitation, Mumbai, an initial set of artificial hands
fabricated by WORTH (Workshop for Rehabilitation and Training of
the Handicapped) Trust, Tamilnadu, was subjected to extended
clinical trials at CMC-Vellore. Improvements including
miniaturization of the electronics, and placement of control
switches inside the socket were made based on further studies and
user feedback. Sizes appropriate for both young children and
adults are available. Commercial manufacture of the artificial
hand is underway, and a project for extended clinical evaluation
for further enhancements and improvements is in progress.
Contact: Prof S
Devasahayam,
surdev@cmcvellore.ac.in, R Lal,
rlal@ee.iitb.ac.in P C
Pandey,
pcpandey@ee.iitb.ac.in
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