Nano-structuring enhances biosensor sensitivity
An optical biosensor can be broadly defined as a device with biological recognition elements or receptors in direct contact with a type of transducer that transforms a biological signal to an electrical one. It typically measures changes in refractive index, providing information about the amount of sample molecules linked to receptor molecules on the sensor surface. The NANOSTRBIOSENS (Nanostructured alumina waveguides for dual-output biosensing: Stress induced fabrication and characterization) project expanded sensing capability by adding a second measure, light scattering, to provide information about the organisation of the molecules as well. Specifically, scientists developed nano-structured single-mode waveguides for dual sensor outputs, total internal reflection and surface-enhanced Raman scattering. The new waveguides can excite multi-surface plasmon waveguide modes. Researchers fabricated nano-structured waveguides made of a thin layer of alumina coated with gold or silver, gold- and silver-coated daisy-like surface nanostructures, and porous anodic alumina-aluminium plasmonic waveguides. The team used two different inexpensive methods for nano-structuring: hydrothermal and anodisation processes. Multilayered and nano-structured alumina waveguides convert waveguide modes to additional modes, while the thin sensing layer enhances sensor control sensitivity in the cover medium. The layers are created by gas or biomolecules around the surface nanostructures. With high sensitivities in both gas and liquid environments, the newly developed waveguides can be used as chips in commercial biosensors such as the blood glucose biosensor.
Keywords
Nano-structuring, biosensor, NANOSTRBIOSENS, alumina waveguides
