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In particular, polymeric materials have been
considered. Our study is focused on the use of
clevios-based sensors, Ionic Polymer Metal
Composites (IPMCs), and solution-based systems to
detect various physical quantities like displacement,
humidity, concentration and so on.
The idea is to use the material as the electrical
transducer and insert the electrical transducer into a
nonlinear circuit. The effect of the coupling of these
components with a nonlinear circuit like the Chua’s
circuit is that a variation of the dynamical attractor
will be obtained as result of the change of the
quantity to which the material is sensible.
Chaos has been already demonstrated to be
helpful in improving the performance of sensors and
other equipments, such as sonar sensors, mechanical
systems and other devices (Fortuna, Frasca, &
Rizzo, 2006): in this project, detection of the given
quantity is made possible by the extreme sensitivity
of the circuit to the variations of its parameters
(Fortuna, Frasca, 2006).
In this study sensors based on water solutions,
that have a behaviour that can be comparable with
RC devices with frequency dependent component
values and so are difficult to realize with classical
components, are also reported.
The proposed sensors will be included in a
complex electro mechanical system in order to study
its self organizing behaviour.
4 STATE OF THE ART
In this Section three types of sensors are discussed.
The first one regards the clevios based sensors.
Clevios is a conductive polymer. The clevios used
(Clevios-P HC V4) is commercially available in a
water colloidal suspension.
A layer of thickness of 100μm is coated on a
surface and then treated in an oven at 80
◦
C for 50
minutes. Two different supports have been used: a
glass support and a PVC foil. The first may be used
to realize humidity, wet and PH sensors as the
resistivity of clevios based materials is sensitive to
these quantities.
Figure 1: The clevios based sensor (glass support).
The second type of device (those were the clevios is
coated on flexible PVC foil) may be used to detect
displacements. In this case, the clevios-based sensor
is considered as an electrical bipole whose resistivity
depends on the surface deformation.
Figure 2: The clevios based sensor (PVC support).
The second type of sensor is realized by using
Ionic Polymer Metal Composites (IPMCs). These
materials belong to the class of wet electro-active
polymers.
They are made of an ionic polymer membrane
covered on both sides with Platinum, which realizes
the two electrodes of the device. IPMCs operate with
low voltage signals, are very light, and have both
actuator and sensor characteristics.
Figure 3: IPMC sensor.
They are used after being cut in strips. If an
electric field is applied across the thickness of a
strip, it undergoes a broad bending deformation.
Viceversa, by bending a strip of IPMC, a voltage
arises between the two metallic electrodes.
Hence, IPMCs can operate as motion actuators
or sensors. Instead, in this work, we exploit the
dependence of the resistivity of IPMC on the
hydration of the membrane to realize a humidity
sensor.
Another proposed device is based on the
resistivity change of a water solution. The device
consists of four copper filaments on a plexiglass
substrate which are electrically connected in two
pairs (the two top ones and the two bottom ones).
ICINCO2014-DoctoralConsortium
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