The idea is similar to using a sleeve when our blood pressure is taken, but on a scale ten thousand times smaller.  Rather than squeezing an arm, a liquid of tiny particles is squeezed by other particles using the tiny forces of light known as optical tweezers.

Dr Paddy Royall, Royal Society University Research Fellow in the Schools of Physics and Chemistry, said: “In the future, this method can be used to access the turgor pressure inside cells and thus to diagnose various diseases, for example certain types of cancerous cells have abnormally low pressure.”

Paper: Direct measurement of osmotic pressure via adaptive confinement of quasi hard disc colloids, Ian Williams, Erdal C. Oguz, Paul Bartlett, Hartmut Lowen, Patrick Royall, Nature Communications, 02 October 2013.