A vibrating wrist band which alerts people who are deaf or hard of hearing when the front door-bell rings has been invented by a group of students at Heriot-Watt University.

The 18 students produced the idea as part of their course in management studies. Group leader Steven Morris, 21, said: "We needed to develop a business idea and launch plan and we thought it would be great to work on something practical which could be of real help to people, so we put together a prototype."