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Functionalization-Free Microfluidic Electronic Tongue Based on a Single Response
journal contribution
posted on 2017-06-28, 00:00 authored by Flavio
M. Shimizu, Fagner R. Todão, Angelo L. Gobbi, Osvaldo N. Oliveira, Carlos D. Garcia, Renato S. LimaElectronic tongues
(e-tongues) are promising analytical devices
for a variety of applications to address the challenges of quality
control in water monitoring and industries of foods, beverages, and
pharmaceuticals. A crucial drawback in the current e-tongues is the
need to recalibrate the device when one or more sensing units (usually
with modified surface) are replaced. Another downside is the necessity
to perform subsequent surface modifications and analyses to each of
the diverse sensing units, undermining the simplicity and velocity
of the method. These features have prevented widespread commercial
use of the e-tongues. In this paper, we introduce a microfluidic e-tongue
that overcomes all such limitations. The key principle of global selectivity
of the e-tongue was achieved by recording only a single response,
namely, the equivalent admittance spectrum of an association of resistors
in parallel. Such resistors consisted of five nonfunctionalized stainless
steel microwires (sensing units), which were short-circuited and coated
with gold, platinum, nickel, iron, and aluminum oxide films. The microwires
were inserted in a chip composed of a single piece of polydimethylsiloxane
(PDMS). Using impedance spectroscopy, the e-tongue was successfully
applied in classification of basic tastes at a concentration below
the threshold for the human tongue. In addition, our chip allowed
the distinction of various chemicals used in oil industry. Finally,
our cleanroom-free prototyping allows the mass production of chips
with easily replaceable and reproducible sensing units. Hence, one
can now envisage the widespread dissemination of e-tongues with fast
and reproducible data.
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Keywords
quality controlequivalent admittance spectrumsteel microwiresaluminum oxide filmssurface modificationsPDMSmass productionwater monitoringimpedance spectroscopycleanroom-free prototypingFunctionalization-Free Microfluidic Electronic TongueSuch resistorschipmicrofluidic e-tongueSingle Response Electronic tonguesoil industry
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