Biomedical Engineering Reference
In-Depth Information
Surface modifications of Co-grown RF-PECVD CNTs networked
films with Au nanoclusters for enhanced NO
gas sensing applications
2
have been also demonstrated by Penza
. [31]. The continuous
detection at sub-ppm level ranging from 100 to 600 ppb NO
et al
gas
in the 30 min step-pulse format using two CNT chemiresistors,
working at 200°C, has been reported. These results demonstrated
that CNT sensor functionalized with Au-loading of 10 nm is of higher
sensitivity and higher resolution than unmodified CNT sensor. The
Au-modified CNT sensor was able to detect more efficiently also
100 ppb NO
2
gas although being with a time-delayed response.
This limit represents the NO
2
attention level for environmental
monitoring and air quality control in the Italian regulations.
Moreover, a chemiresistor based on CNT networks functionalized
with sputtered Pt and Pd nanoclusters of nominal thickness of
5 nm has been fabricated by RF-PECVD technology for sub-ppm
gas sensors to address chemical detection of hazardous pollutants
such as NO
2
. [247] demonstrated that the metal-
functionalized CNT sensors provided higher sensitivity compared
to unmodified CNTs for significantly enhanced gas detection of NO
gas. Penza
et al
2
,
2
H
, and CO up to a low limit of sub-ppm level. Pt- and Pd-
functionalized CNT sensors exhibited better sensing performances
compared to unmodified CNTs, and especially Pt-modified CNT
sensor was found to detect NO
S, NH
2
3
gas in the range from 100 to 600 ppb
at higher sensitivity than Pd-modified CNT sensor, working at 200°C.
These results provide clear evidence that metal-functionalized
CNT-based sensors are excellent candidates for air-pollutants'
environmental monitoring. Also, Penza
2
. [246] demonstrated Au
and Pt nanocluster functionalized MWCNT chemiresistors for NO
et al
2
and NH
gas sensing at high temperature in the range from 100 to
250°C. MWCNTs were synthesized by PECVD onto Cr-Au patterned
alumina substrates, provided with 3 nm thick Fe growth catalyst. Au
(6-20 nm) and Pt (6-60 nm) nanoclusters were then sputtered onto
MWCNTs surface. The authors found that the sensitivity of Pt- and
Au-functionalized MWCNTs to NH
3
and NO
improved by one order
3
2
of magnitude. Furthermore, Penza
. demonstrated vertically
aligned CNTs grown onto nanosized Fe-coated alumina substrates
for gas and VOC detection. These vertically aligned CNTs were
catalyzed by Pt, Ru, and Ag nanoclusters on the top of the vertically
aligned nanotubes layer for enhanced detection of NO
et al
, ethanol,
and toluene up to a low limit of sub-ppm level [249] and for landfill
gas monitoring applications [36].
, H
2
2
