First prize in this year's James Dyson Award has gone to London-based product design student Michael Chen, whose Reactiv jacket was designed to combat hostile cycling conditions in the city.
The Reactiv jacket uses an accelerometer to sense movement, changing the colour of LEDs on the back from green when accelerating, to red when braking.
A "tilt switch" in the jacket makes LEDs in the arm flash amber when the wearer lifts their arm to indicate a turn.
James Dyson said: "Michael took a very real problem for cyclists visibility - and has engineered a solution. Reactiv is a brilliant safety device, especially when cyclists can be so vulnerable. The use of arm movements to operate the tilt switches and LEDs is especially clever".
The James Dyson Award is supported by the James Dyson Foundation, a registered charity whose aim is to "inspire and excite" young people about design engineering.
Michael would like to his jacket into production, hoping that it will reduce the 20,000 incidents involving cyclists on London roads every year.