Gold nanoparticles enable ultrasensitive sensor

100 times more sensitive for medical diagnostics and measuring air pollution
23rd January 2019

Researchers at the University of Bath have developed a new type of sensor that is 100 times more sensitive than today’s sensors.

The sensor is made up of a series of gold disk-shaped nanoparticles on a glass slide. The team from the Department of Physics found that when they shone an infra-red laser at a precise arrangement of the particles, they started to emit unusual amounts of ultra violet (UV) light.

This mechanism for generating UV light is affected by molecules binding to the surface of the nanoparticles, providing a means of sensing a very small amount of material. This could be used to develop new ultra-sensitive sensors for air pollution or for medical diagnostics.

“This new mechanism has great potential for detecting small molecules. It is 100 times more sensitive than current methods,” said Dr Ventsislav Valev, Reader in Physics at the University of Bath and a research fellow of the Royal Society. “The gold nanoparticle disks are arranged on a glass slide in a very precise array – changing the thickness and separation of the disks completely changes the detected signal. When molecules bind to the surface of a gold nanoparticle, they affect the electrons at the gold surface, causing them to change the amount of UV light they emit, and the amount of UV light emitted would depend on the type of molecules that bind to the surface.”

The nanoparticles were fabricated by US team members at Northwestern University in Illinois.

“This technique could enable ultra-sensitive detection of molecules in tiny volumes,” said Dr Valev. “It could in the future be used for detecting very low concentrations of biological markers for the early diagnostic screening for diseases, such as cancer.”

The study has demonstrated the proof of principle for this new sensing mechanism. The team would next like to test the sensing of various types of chemicals and expects the technique to be available to other scientists to use within five years.

The work was published in ACS Nanoletters