How electrochemistry can fingerprint a drink
A plain-language guide to voltammetry: how a tiny voltage sweep can turn the chemistry of a drink into a pattern a phone can compare.
"Electrochemistry" sounds intimidating, but the idea behind our pen fits in a paragraph. Here's the plain-language version.
Electrodes and a voltage sweep
The tip of the pen holds a few tiny electrodes: conductive surfaces that touch the liquid. The electronics apply a slowly changing voltage between them. That process is called voltammetry.
As the voltage changes, some molecules in the drink gain or lose electrons at the electrode surface. Each time that happens, a small electric current flows. Different molecules react at different voltages, and by different amounts.
From current to fingerprint
If you plot current against voltage you get a curve called a voltammogram. A drink with a different mix of compounds gives a differently shaped curve: peaks in different places, of different heights. That curve is the drink's electrochemical fingerprint.
Researchers have used exactly this approach to tell wines and whiskies apart. One study used metal electrodes in a simple supporting electrolyte (Wójcik et al., 2019). Another used cheap, disposable copper and gold electrodes (Novakowski, Bertotti & Paixão, 2011). A commercial device, Eluceda's E-Sens, uses custom electrodes and compares readings against a database of authentic samples (The Spirits Business, 2021).
Comparing against the real thing
A fingerprint only means something if you have one to compare it with. That's why drinkYangu has three parts:
- The pen records the voltammogram.
- The app sends it for comparison and shows the result.
- The signature database holds fingerprints measured from genuine bottles, ideally supplied by the brand owners themselves.
The comparison is statistical. Software looks at the whole shape of the curve and asks how closely it matches the genuine signature for that product. The honest answer can be "matches", "doesn't match", or "can't tell".
The hard parts
- Stability. Electrode surfaces change with use and temperature. Readings have to be repeatable from one dip to the next.
- Natural variation. Genuine whisky varies a little between batches. The database has to capture that range.
- Clever fakes. Genuine whisky diluted slightly, or blended with a cheaper whisky, is harder to spot than industrial ethanol with colouring.
These are exactly the questions our whisky feasibility study sets out to answer.