Quantum-driven biosensor enables self-illuminated molecular detection

Optical biosensors typically require external illumination to detect molecular interactions on nanoscale surfaces. While highly accurate, they have been difficult to miniaturize for point-of-care diagnostics due to the need for lasers, lenses, and other hardware. 

To solve this, EPFL engineers used a quantum phenomenon, inelastic electron tunneling, to both generate and detect light on a single chip. This approach enables compact, label-free biosensing at extremely low concentrations. 

“What we have done is create a nanostructure that both forms part of this insulating barrier and increases the probability that light emission will take place,” 
explains researcher Mikhail Masharin. 

At the heart of the sensor is a gold metasurface designed from a mesh of gold nanowires that function as nanoantennas. These enhance light emission when electrons cross an insulating aluminum oxide layer and interact with a gold film. The sensor then measures how this light changes when biomolecules are present. 

“Tests showed that our self-illuminating biosensor can detect amino acids and polymers at picogram concentrations – that’s one-trillionth of a gram,” says Laboratory head Hatice Altug. 

The EPFL sensor uses less than one square millimeter of active surface area and is fabricated using standard microfabrication processes. 

“Our work delivers a fully integrated sensor that combines light generation and detection on a single chip,” summarizes Ivan Sinev, researcher at the Bionanophotonic Systems Lab. 

COMPAMED-tradefair.com; Source: Ecole Polytechnique Fédérale de Lausanne