The pandemic sent scientists scrambling to develop COVID-19 diagnostic kits, with everything from breath tests to carbon nanotube devices. As helpful as these devices are, many are designed to recognise a single biomarker, limiting their effectiveness across other disease spectrums.
Take, for example, plasmonic biosensors. These miniature sensors are used in an array of biomedical applications, detecting the presence of a given molecule with high sensitivity by recognising its signature optical properties. However, for them to be widely adopted, plasmonic biosensors should ideally be able to sense diverse molecules.
A team of researchers, led by Principal Scientist Jinghua Teng and Scientist Meng Zhao from A*STAR’s Institute of Materials Research and Engineering (IMRE) hypothesised that ultrathin sheets of a material called niobium diselenide (NbSe2) could be used to create adjustable plasmonic devices.
The team, in collaboration with researchers from the National University of Singapore and the Southern University of Science and Technology, developed an electrochemical method of making high-quality NbSe2 flakes, dozens of times larger than those produced in previous studies. “Only with these large and high-quality samples can we characterise macroscopic plasmonic behaviour,” explained Teng.
The team then created plasmonic setups using a conductive liquid as the dielectric medium to shuttle positive and negative ions under an electric current.
Conventional methods for varying the plasmonic resonance wavelength rely on changing the sensor material’s size, shape, or composition. Interestingly, the team found that simply changing the voltage applied altered the plasmonic resonance wavelength of NbSe2, allowing the device to detect a range of molecules on demand.
“With a single device, we can do the detection job that usually requires multiple plasmonic devices,” said Teng.
This innovation has the potential for use across a range of other industrial applications including energy harvesting and telecommunications, paving the way for a new generation of smart, multifunctional sensors.
“In the near future, we hope to develop a versatile biosensing platform based on this new plasmonic structure,” said Zhao. “We also hope to optimise the plasmonic structure to achieve ultrahigh sensitivity for detecting multiple biomolecules—proteins, DNA, and more—in a single device.”
The A*STAR-affiliated researchers contributing to this research are from the Institute of Materials Research and Engineering (IMRE).
