Researchers have developed a new technique to measure nanoscale forces in a fluid medium, which they say could revolutionise our understanding of a host of biological and physical phenomena.
The super-resolved photonic force microscope (SRPFM) precisely measures how nanoparticles are displaced by tiny forces.
It can detect forces as small as 108.2 attonewtons (the prefix “atto” means one million million millionth) in water – a scale so minute that it compares to measuring the weight of a virus.
Fan Wang from Beihang University in China, who led the research, says the key to this ultra-sensitive measurement is in the use of lanthanide-doped nanoparticles, trapped by optical tweezers, which are then used to probe the minute forces at play within biological systems.
“Understanding these tiny forces is crucial for the study of biomechanical processes, which are fundamental to the workings of living cells,” says Wang.
“Until now, measuring such small forces with high precision in a liquid environment was a significant challenge due to factors like probe heating and weak signal issues.”
Study co-first author Lei Ding from RMIT University in Australia says the innovation not only enhances the resolution and sensitivity of force measurements but also minimises the energy required to trap the nanoparticles, thereby reducing potential damage to biological samples.
“Our method can detect forces down to 1.8 femtonewtons per square root of the bandwidth, which is near the theoretical limit imposed by thermal noise,” says Ding.
The research is published in Nature Photonics.
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