![](bg8.png)
response must be normalized, and several
classification methods can be explored.
Furthermore, small, lightweight and low-power
pumps can be used in future versions of the device, so
it can achieve portability without the need of an
electric generator.
In what concerns to the electrical part, the
conductivity meter architecture should be re-designed
to be simpler and easily scalable. For instance, the
possibility of generating an input digital wave should
be explored. In addition, the electrodes finishing
surface should be more corrosion-resistant (the use of
nickel and gold, or platinum might be a solution). The
duration of the experiments related to the electrical
signals should be longer, allowing the study of the
response at different measurement intervals, to
improve quantification and interpretation of results.
The studies performed so far intend to
characterize the device, identify its limitations, and
optimize the technology. That is why, the tests were
performed successively in cycles during several
minutes. Nevertheless, our vision is to achieve a
device that gives a response in the range of seconds.
The final goal is to accomplish a portable and
user-friendly device. Accuracy, stability, and
scalability are imperative to get to an E-nose, that can
be explored towards several applications in
environmental protection, security, product quality,
or medical research.
ACKNOWLEDGMENTS
This work was supported by the European Research
Council (SCENT-ERC-2014-STG-639123) and
UCIBIO, financed by FCT/MEC (UID/Multi/
04378/2013) and co-financed by the ERDF under the
PT2020 Partnership Agreement (POCI-01-0145-
FEDER-007728). The authors thank FCT/MEC for
the research fellowship PD/BD/105752/2014 for A.P.
The authors also acknowledge funding from CNPq,
Brazil (400740/2014-1).
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