Product category: Electromechanical Components
News Release from: EMS | Subject: Margaret Rose Bio Engineering unit
Edited by the Electronicstalk Editorial Team on 25 June 2001

EMS aids development
of prosthetic hands

EMS has provided products and technical guidance on small DC motors and gearheads to the team at the Princess Margaret Rose Bio Engineering unit to help tham produce a child size artificial hand

Electro Mechanical Systems has provided products and technical guidance on small DC motors and gearheads to the development team at the Princess Margaret Rose Bio Engineering unit in order that they produce a child size artificial hand that offers realism and functionality, thereby enabling youngsters to move, pick-up and place objects with relative ease.

Though still in the clinical trials stage, the development team is hoping that someone will provide additional funding so that the project may be completed and the hands be made available to those who need them.

It also needs to be said that the self-esteem and self-confidence of the recipients is raised to such a degree that they become well adjusted adults, able to lead relatively normal lives.

Presently the prosthetic hands are covered using PVC, the standard material used throughout the industry.

It is not however, without its disadvantages.

PVC for example soaks up newsprint and is harder to clean than the alternative silicone covering used on some prosthetics.

Silicone has a better 'depth' of colour than PVC and is therefore more realistic.

Coverings are cast from the hands of volunteers so have all of the features and appearance of natural skin.

The development programme has lasted for some twenty years.

David Gow, the Director of Rehabilitation, Engineering Services, has been with the project from day one.

It goes without saying that his knowledge is second-to-none and his value to the team which is in the world's top five in its field, is beyond calculation.

The Edinburgh group first developed an adult size mechanical hand while a similar project in Sweden was working on a child's hand.

The problem with mechanically operated prostheses is that a high degree of wrist muscle development is required to operate the limb successfully.

This is usually present in adults but not in children.

An electrically operated prosthesis would be the answer.

David Gow is gracious in his recognition of EMS who he says have been working with him from the commencement of the electronic hand programme.

Happily, Aldermaston based EMS, now arguably the UK's leading provider of specialised small drive products, were able to help because market led demand for smaller motors and gearboxes in the micro drive area accelerated existing development programmes to such a degree that ultra compact, high power-to-weight ratio units ideally suited to the Edinburgh team's application soon became available.

In the current generation of child size prostheses, EMS provide two 10mm diameter planetary gearheads (1016M006G), offering 64:1 reduction whilst the equivalent adult prosthiesis uses a single 10mm diameter unit (1016M006G), along with a 14mm unit (1319E006S) which offers 43:1 reduction.

In both cases the drive motor is located in the thumb.

All are compact, powerful, extremely lightweight and reliable.

It is now possible to fit electrically operated hands to children of just two years of age.

Experts say that this is the ideal age for children to receive a hand as limbs fitted later than this are often discarded by the user.

From 2 years to adulthood, three sizes of hand are generally required.

The smallest hands weigh just 130g inclusive of its external battery and the hand is removed for recharging.

A 1h charge gives 4-5h operation.

Obviously the hope is to develop an internal battery at some point which will make the limb completely self contained and more convenient to the wearer.

At GBP 5000 to 6000 each, they are not cheap but production on a commercial scale should see the unit price fall considerably.

Smaller limbs, when superseded by a larger limb on a growing child can be refurbished but at present this seems not to be economically viable.

The important work being undertaken in Edinburgh is a credit to all involved.

As a project it lacks attention because it is not as glamorous as others but when looked at analytically it stands up to any scrutiny for this offers independence and self-esteem to children.

It is a credit to our National Health Service and a credit to the volunteers and children who have allowed themselves to be used in the programme so that others may benefit.

It is a credit to the suppliers who have worked tirelessly to help develop and improve the limbs, but most of all it is a credit to the men and women who staff the Bio-Engineering unit. Request a free brochure from EMS....

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