Scientists have taken a first step to developing a crash helmet that changes colour depending on the severity of the wearer’s head injury.

Researchers from the University of Pennsylvania have produced a material containing opal-like polymer crystals which change colour depending on how hard they are hit. The hope is that the crystals could be used in the production of safety helmets to provide an immediate indication of head trauma after a crash, giving medical professionals an early idea of the damage a person may have suffered.

In tests, scientists applied forces to the crystals equivalent to a car crashing into a brick wall at 80mph causing them to change from red to green.

Melanie Williams, a serious injury solicitor based in Thompsons Solicitors’ London office, said: "Serious head and brain injuries are life-changing and disabling, but the effects are often hidden at the time that they occur.

"The possibility of a crash helmet that could give paramedics an early indication of the damage a person may have suffered would be hugely beneficial. From our work with people who have suffered a head or brain injury, we know the importance of early detection and the impact that can have on the extensive rehabilitative care required post injury. Anything that enables medics to start the right treatment at the earliest possible stage would be very welcome."