An electrical fuse is a simple, low-cost,
single-use device that protects electrical circuits. When electrical current
is too much for a system, the fuse material melts, breaking the circuit.
Researchers from the University of Durham in England have come
up with a chemical fuse that works on a similar principle. The chemical
fuse includes a thin layer of material that changes when it is exposed
to a gas. The change is enough to permanently disrupt a flow of electrical
current through the film.
The chemical fuse could eventually be used as a disposable sensor
to monitor airborne pollutants. It could also be used as the sensing element
of a cheap, disposable handheld personal breathalyser to monitor the concentration
of alcohol in the blood.
The researchers constructed chemical fuses by using an inkjet
printer to print a mix of a polymer that conducts electricity and polystyrene
sulfonated acid. The sensitivity of the device is determined by the number
of layers printed.
The researchers tested the device by exposing it to pulses of
methanol or ethanol vapor. The initial exposure to the vapor rapidly changed
the polymer, irreversibly decreasing the amount of current it could conduct.
The technique produces inexpensive, simple sensors that can be
printed on a variety of surfaces, including flexible materials.
The chemical fuse could be ready for commercial use in two to
five years, according to the researchers. The work appeared in the January
3, 2005 issue of Applied Physics Letters.
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