By Ben
Coxworth
October 12, 2022
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A proof-of-concept version of the sensor changes color
(circle at right) as a piece of frozen pork thaws Ptc: Adapted from ACS Sensors
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Developed by a team from the Istituto Italiano di
Tecnologia (Italian Institute of Technology), the food-safe device is currently
in functional proof-of-concept form.
It incorporates two electrodes – a magnesium anode and a
gold cathode – which are separated by a frozen electrolyte solution. In various
versions of the sensor, that solution has contained salts and electrolyte-rich
grape, apple and melon matter.
As long as the electrolyte solution remains frozen, nothing
happens. If it thaws, however, it allows electrons to flow from the anode to
the cathode, causing the sensor to generate an electrical current. That current
in turn causes a red-cabbage-juice-based solution to change from a reddish-purple
to blue color. It then stays blue, even if the sensor is refrozen. The
temperature at which the electrolyte thaws can be tuned within a range of 0º C
to -50º C (32º F to -58º F).
All of the components are currently contained within a
beeswax body. It is hoped that once developed further, the technology could
take the form of a thin, inexpensive, single-use, edible material that could be
applied directly to the food items.
A paper on the research, which is being led by Ivan Ilic
and Mario Caironi, was recently published in the journal ACS
Sensors.
Source: American Chemical Society