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Or ganic Thin-Film Transistors for Inor ganic Substance Monitoring 75

3.5
3.0
2.5
m (μA/ppm) 1.5
2.0

1.0
0.5
0.0
–0.5
20 10 0 –10 –20 –30 –40 –50
V (V)
g
FIGURE 2.9 The slopes of the linear calibration curves of D3ANT OTFT exposed
to NO at gate voltage ranging from +10 to −40 V with associated error bars.
2
curves for NO reported as a function of the gate voltage are shown
2
with the associated error bars. OTFT sensor exhibits a sensitivity
enhancement of 4 orders of magnitude while the device switches
from the off to the on regime. The sensitivity enhancement induced
by the gate bias is a general property of an OTFT that makes it par-
ticularly promising for sensing applications.
In conclusion, in this chapter we described a new p-type organic
semiconductor with high stability in air, processable from solution
and with an amorphous structure, exhibiting differential sensibility
to NO and NO down to the ppb level and very low cross-sensitivity
2
to potential interfering gases such as carbon monoxide and hydrogen
sulfide. The future aim of this research project is to develop low-cost
and reliable NO sensors easily implementable in portable detectors
x
for a fast environmental pollutant monitoring as well as for diagnos-
tic applications. Such goals could allow the control of the physiologi-
cal state of unhealthy subjects exposed to unsafe atmosphere, as well
as the pollution level of the area surrounding them.

2.4 Gold Nanoparticle-Modified FET Sensors
for NO Detection
x

2.4.1 Introduction
Nanoparticle (NP) based gas sensors have been strongly investigated
in the last decade since they can offer several advantages, such as the
increased surface area–volume ratio, and new reactivity properties
resulting in brand new or improved sensing features, in terms of sen-
150
sitivity, selectivity, as well as response and recovery time. Moreover,