Patients with muscle-weakening conditions could be helped by a powered device developed at Cambridge University.

The "mobile arm support" is aimed at people with conditions such as muscular dystrophy and motor neurone disease - many of whom have not got the ability to raise and lower their arms.

The arm is supported by a sling so that it can be moved horizontally - both backwards and forwards and to left and right.

The other hand operates a switch which moves the sling up and down.

The combined effect allows patients to carry out light fetching and carrying tasks which would normally be beyond them.

There are now plans to market the device through a private company.

Samuel Lesley, one of the researchers at the university's Department of Engineering, said: "Because of the way this device combines electrically powered vertical movement with muscle-powered horizontal movement, the user can make natural-looking movements.

Independent living

"It has the potential to give people with diseases such as muscular dystrophy a greater degree of independence and it can also help exercise joints and muscles."

The machine has been tested by more than 80 volunteers - the vast majority said they thought it would be useful in their day to day lives.

Kirsty White, disability awareness training co-ordinator for the university, has herself been using it.

She said: "The mobile arm support system is one of the most effective pieces of equipment I have used.

"It is in general very reliable and enables me to undertake a range of very practicial activities."

Jon Michaelis, the managing director of Neater Solutions, which will market it, said: "I am extremely impressed with the unique design of this powered mobile arm support.

"The University of Cambridge has come up with a device that easily out-performs the many that I have tried."