As a method to combat human wine critics’ personal biases and provide more objective feedback, advances in artificial tongue technologies have been made in recent years that put the sensitive discernment of various qualities of taste in the hands of science. Recently, researchers at Interdisciplinary Nanoscience Centre (iNANO), at Aarhus University have developed a nanosensor capable of measuring the sensation of astringency when drinking wine. From IEEE Spectrum:
In research published in the journal ACS Nano, the Danish researchers report having developed an optical sensor based on surface plasmon resonance, which is based on the collective oscillation of electrons that occurs on the surface between a metal and a dielectric when stimulated by light.
Surface plasmon resonance (SPR) is attractive to sensor designers because the resonance wavelength is very sensitive to conditions at the interface. Because of this sensitivity, SPR has been exploited, for example, to detect biomolecules (blood glucose, for example) clinging to the conductor surface.
The design of the SPR-based nanosensor in this case involves a small plate coated with gold nanoparticles. The researchers then put some of the proteins found in human saliva on the plate. When the wine comes in contact with the plate, the gold nanoparticles act like a lens that can focus a beam of light below the diffraction limit so that it becomes possible to measure down to 20 nanometers. This makes it possible to follow the salivary proteins and see how the interaction with the wine impacts them.
In effect, the SPR-based nanosensor is using salivary proteins to measure the sensation of astringency we have when we drink wine.