Developing tools for nano-scale investigations – from optical forces in the near field to medical applications

19 February 2018, 5.00 PM - 19 February 2018, 6.00 PM

Dr Massimo Antognozzi (Physics Bristol)

Berry lecture theatre (3.21)

Nano-scale phenomena have the ability to cross boundaries between disciplines resulting sometimes in unexpected scientific discoveries and sometimes in technological breakthroughs. Here we will describe how, the development of low compliance micro-sensors to study bio-molecular machines resulted in the first-time measurement of the Belinfante’ optical spin momentum. Belinfante predicted this component of the optical momentum more than 70 years ago and, by using extremely sensitive micro-cantilevers we could confirm the existence of this component in an evanescent field as well as its correct dependency on the wave handedness.

Setting the goal to observe Belinfante’s optical force resulted in a significant improvement of our microscope resolution that led to an unexpected application this time in microbiology. While we were developing our technique, Sandor Kasas’ group in Lausanne discovered that live bacteria adsorbed onto a micro-cantilever increased the sensor fluctuations indicating the possibility that living bacteria exhibit nano-scale fluctuations. The authors suggested that this effect could be used to distinguish living from dead bacteria when studying antimicrobial susceptibility. This is a completely unexpected result and it is still puzzling microbiologists. After a few attempts at reproducing Kasas’ results, Dr Charlotte Bermingham in our group discovered that this unknown bacterial activity could be observed readily using an evanescent field illumination. Few seconds are now sufficient to determine if a microorganism is alive or dead and we have a clear path towards a fast and robust diagnostic device that could ultimately help general practitioners when prescribing antibiotics to patients.

I will conclude the talk indicating new areas of research we are currently developing and how they fit into the wider nano-science research landscape.

Contact information

For further information, contact Molly Hackett at

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