Instrumentation & Measurement Magazine 26-1 - 35

Living Sensors:
The Greenest Paradigm in
Instrumentation and Measurements
Carlo Trigona
T
he advent of latest technologies, rising materials and
solutions is enabling a brand-new wave of innovation.
Going into more detail on electronic solutions,
measuring architectures, transducers and sensors, a new environmental
issue has emerged concerning the toxicity of such
components throughout manufacturing and through use in
peculiar applications [1], [2]. It should be noted that these
electronic devices typically contain dangerous materials and
noxious components, like batteries, which might be venturous
for the local communities, and at the same time, have detrimental
effects on nature [2]. In this framework, considering
the era 4.0 with industry/agriculture 4.0, precision agriculture
and smart solutions [3], [4], new ideas and paradigms in
the context of sensors have overthrown " classical " devices,
such as silicon-based elements, MEMS, semiconductors, and
solid state chips. As a matter of fact, the semiconductor manufacturing
process and the fabrication of integrated sensors
represents an un-green step, far from being considered ecofriendly,
considering that the CO2
emission and pollutants is
quite significant during manufacturing [5], [6]. They present,
at the same time, limited biodegradability and lack the ability
to be absorbed by the environment. In the perspective to conceive
more eco-friendly devices, several approaches, mainly
based on new compounds, have been addressed in the literature
[7].
Indeed, a trend is emerging in the field of new materials
and solutions that lends itself to the realization of the
next-generation of sensing systems based on advanced technologies
that cut across the engineering sciences [8]. In fact,
to go beyond the limits of silicon, for its un-green characteristic,
the proposed solutions are mainly based on organic
molecules and polymers that show desirable properties for
sensors and electronic elements while also considering the
possibility to modify the concentration of dopants [9]. In fact,
conductive polymers are often intrinsically conductive or
semiconductive. The literature presents various solutions to
tune the electrical properties of conductive polymers such as
organic synthesis and advanced dispersion techniques [10].
The proposed solutions include polyacetylene, polypyrrole,
polythiophenes, and polyaniline [11]. Through these materials
and by using specific polymeric substrates, it is possible to
implement organic devices, transducers, sensors [12] and converters
such as photovoltaics typically based on polymeric
substrates like polyethylene terephthalate or polycarbonate
[13], [14]. It is worth noting that batteries and power generators
have been also implemented through lithium metal
polymer solutions [15].
One of the main advantages of organic devices is the possibility
of manufacturing components and circuits over large
areas, with low cost; above all, the process is suitable to obtain
greener solutions compared to classical inorganic or siliconbased
sensors. In this direction, the literature shows also a
tendency to use biopolymers as substrate, for example cellulose
or bacterial cellulose [16], [17], also useful for sensors
and resonators [18], [19]. Such solutions both at the sensor and
electronic components levels lead to a CO2
emission equal to
almost 0 and biodegradability close to 100%. In fact, the state
of the art demonstrates that the procedure to fabricate siliconbased
systems, including the metallic layers and materials
used in electronic devices, contributes with emission of about
11.3 kg CO2
e/kg [20]. It is worth noting that in this latter case an
increase of about 25% has been detected in about 9 years [21].
There are several on-going initiatives that aim to reduce the
emission related to the process, which is a primary task on the
path towards carbon neutrality by using alternative solutions.
Polyethylene terephthalate (PET) and synthetic rubber result
in emission of about 5 kg CO2
e/kg, while plastic, carbon black
and paper as element for sensors and electronic devices, involve
maximum emissions of about half of this latter solution.
Recycled high-density polyethylene (HDPE) and recycled PET
are of interest considering an emission of about one order of
magnitude less with respect to silicon-based systems, and a
biodegradability much higher, and in some case close to 100%
compared with silicon devices [22]. In the perspective to go
The author received the Instrumentation and Measurement Society's 2020 Young Engineer Award.
February 2023
IEEE Instrumentation & Measurement Magazine
1094-6969/23/$25.00©2023IEEE
35
Instrumentation & Measurement Magazine 26-1

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