Biomedical Engineering Reference
In-Depth Information
temperature by sensors with an active layer of MWCNTs plasma-
treated (RF power: 100 W; work pressure: 0.1 Torr; treatment
time: 10 min; oxygen plasma: 20%) and subsequently annealed in
situ at 480°C for 2 h. This enhanced sensitivity was probably due to
the presence in these samples of catalytically active metals (i.e., Co,
Fe, and Al), which played an important active role in the detection
of ammonia. These oxygen-treated MWCNT sensors responded to
NH
concentrations as low as 200 ppm. These CNT films behaved as
3
p
-type semiconductor in presence of NO
and NH
gases.
2
3
Figure 9.30
(
)
Image of a four-element microhotplate sensor array based on
drop-coated MWCNT layers and treated by plasma-oxygen.
(
Top-Left
) Structure of the microhotplate sensor. (
Top-Right
) Response at room temperature to increasing
concentrations of NO
Down-Left
of a plasma-oxygen treated MWCNT-
sensor (experimental conditions in text). (
2
)
Response at room temperature to increasing concentrations
of NH
Down-Right
of a plasma-oxygen treated MWCNT-sensor. This figure
is reprinted and adapted with permission from Elsevier
[149].
3
Penza
. [247] demonstrated a gas chemiresistor fabricated
directly onto alumina substrates using RF-PECVD grown MWCNTs
for gas detection of air pollutants, at a working temperature
of 200°C. Functionalizations of MWCNTs tangled bundle films
with nominally 5 nm thick Pt- and Pd-nanoclusters, prepared by
et al
