Good Thinking

Modern version of ancient musical instrument detects poisons

The new-fangled mbira in use
The new-fangled mbira in use
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The new-fangled mbira in use
The new-fangled mbira in use

Also known as the thumb piano, the mbira is an African musical instrument that has been around in one form or another for at least 3,000 years. Now, however, scientists have developed a new version that – when combined with a smartphone – can detect toxic substances and possibly even counterfeit medication.

A traditional mbira consists of multiple metal tines of varying sizes, mounted on a wooden sounding board. When one of those tines is plucked by the user's thumb, it produces a specific musical note. The different tines produce different notes based on their size, although their density also affects their sound.

Led by Dr. William Grover, a team from the University of California, Riverside recently created an mbira that has just a single, hollow, U-shaped tine. When that tine contains nothing but air, it produces a note of G-sharp when plucked. If the tine is filled with water, though, that note drops to an F-sharp.

While the difference between those two notes is easily heard, the sound frequencies produced by Grover's mbira are also subtly affected by the density of the liquid inside the tine. These differences in frequency can't be detected by the human ear, but they can be detected by a free web-based smartphone app.

In lab tests, that app was easily able to distinguish between the sounds made by similar-looking samples of non-toxic glycerol and toxic diethylene glycol, plus it could tell the difference between solutions containing varying concentrations of sodium chloride. On the other hand, when it was used to analyze six samples of cold medication from different production lots and with different expiration dates, it confirmed that they were all the same legitimate substance.

In field tests, the instrument has also been used to measure the fat content of bison milk in India, and to indicate sediment levels of river water in California.

Grover now hopes that the device will find use in developing nations, where it could reportedly be built from scrap materials, and be easily used with little training. It can be seen and heard in use, in the following video.

Source: American Chemical Society via EurekAlert

Sensors that are “music to your ears” - Headline Science

Almost certainly Indian buffalo, not bison. The former is commonly domesticated, the dangerous giant Gaur or Indian Bison is generally wild except for a few crossbreeds semi-domesticated by certain tribes there.
Ralf Biernacki
Measuring a single parameter---liquid density---is not sufficient to distinguish between chemical solutions. It is trivial to reproduce a given density (e.g. 0.9% NaCl solution) with a suitably proportioned solution of a different chemical (e.g. KCN).
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