Southampton scientists move closer to bionic hand
22 September 2005
Scientists at Southampton University have developed a new ultra-light
artificial hand that can mimic the movement of a real hand better than any
currently available. This research was presented at the Institute of Physics
conference Sensors and their Applications XIII on 6-8 September.
Currently available prosthetic hands are either simple mimics that look
like a hand but don’t move or moving hands which have a simple single-motor
grip. The human hand has 27 bones and can make a huge number of complex
movements and actions. Dr Paul Chappell, a medical physicist from the
University of Southampton has designed a prototype hand that uses 6 sets of
motors and gears so that each of the five fingers can move independently.
This enables it to make movements and grip objects in the same way a real
human hand does.
The new hand, called the ‘Southampton Remedi-Hand’, can be connected to
muscles in the arm via a small processing unit and is controlled by small
contractions of the muscles which move the wrist.
Dr Chappell said: “With this hand you can clutch objects such as a ball,
you can move the thumb out to one side and grip objects with the index
finger in the way you do when opening a lock with a key, and you can wrap
your fingers around an object in what we call the power grip — like the one
you use when you hold a hammer or a microphone.”
Dr Chappell and colleagues in the School of Electronics and Computer
Science at the University of Southampton set out to try and build a hand
which could mimic the movement and flexibility of the human hand and which
was also very light. Heavy prosthetics can be extremely uncomfortable and
cause injury to the area where it joins with the arm. The new hand they’ve
developed is only 400g (even lighter that a real hand which weighs on
They built the Remedi-Hand in three parts — the three middle fingers are
very similar in size and movement so they made those identical. The pinky is
a smaller version of the same. Each of these four fingers are made up of a
motor attached to a gearbox attached to a carbon fibre finger. All of this
is fitted to a carbon fibre palm. But the thumb was much more complicated
and is the first artificially-made opposable thumb.
The human thumb can move in special ways the fingers can’t. It can rotate
as well as flex and also move in a variety of different directions. It can
also oppose (touch) each of the fingers in the hand to form a ‘pinch’. To
mimic this, the Remedi-Hand uses two motors – one to allow it to rotate and
one to allow it to flex. “The real thumb can move in five types of way,
we’ve managed to create a thumb that can mimic at least two of these which
is a really exciting achievement. It’s a thumb that has really good
flexibility and functionality” says Dr Chappell.
One of the key differences between mechanical, artificial, limbs is that
they aren't able to sense pressure or touch in the same way human limbs can.
The next stage of Dr Chappell’s research is to integrate the latest sensor
technology with the Remedi-Hand to create a ‘clever’ hand which has better
functionality and move like a real hand, but which can also sense how
strongly it’s gripping an object or whether an object is slipping.
Dr Chappell and colleagues have already designed this ‘clever’ hand and
are about to start building a fully functioning prototype. It will have
piezo-electric sensors in each of the five fingertips which will detect how
much force is being exerted on the tip and translate this information into
an electrical signal which will be fed to a small processor.
Dr Chappell said: “The aim is to create a hand with the sort of
functionality a human hand has but also a sense of touch. This will let the
hand know how tightly to grip an object like a coffee cup without dropping
it, but not so tightly that it’s crushed. It’ll also have an integrated
slip-sensor which will tell the hand if something is beginning to slip out
of its grip so it can grip slightly harder. It’ll be quite a clever system.”
The development of the prototype hand was funded by Remedi, a charity and
For further information:
David Reid, Senior Press Officer,
Institute of Physics, Southampton University