Accommodating these markers causes the highly-sensitive sensors to bend like a diving board and this bend indicates the level of virus in the body, explained lead investigator Dr Rachel McKendry of University College London and the London Centre for Nanotechnology.

BBC: 'Self-monitoring device' for HIV

Prof Robert West, from the health behaviour research unit at University College London, said it was important to remember that smoking had more effects on the body than leading to an early death, such as ageing the skin.

BBC: Women smokers who quit by 30 'evade earlier death risks'