Biomedical Engineering Reference
In-Depth Information
of ppm with a detection limit of 44 ppb for NO
and 262 ppb for
nitrotoluene. The response time is in the range of a few seconds,
and the recovery time is longer in the range of minutes by using UV
illumination. The gas sensitivity is less than 6% for all tested devices,
comparable with commercial gas sensors. The extended detection
capability from gas to organic vapors is attributed to a direct charge
transfer on the individual semiconducting SWCNTs' conductivity
with additional electron hopping effects on intertube conductivity
through physically adsorbed molecules between individual SWCNTs.
Figure 9.29 shows results achieved by Meyyappan [28].
2
Figure 9.29
(
) SEM image of IDE and SWCNTs across two Au-
electrodes. (
Top-right
at room
temperature, without UV light during recovery upon N
a, b, c-left
) Sensor response toward NO
2
gas,
2
and with UV light in the recovery, simultaneously with N
gas.
2
Calibration curve for NO
obtained from data in the b-graph.
2
(
) Sensor response toward nitrotoluene
at room temperature. Calibration curve for nitrotoluene
obtained from data in the a-graph. This figure is reprinted
and adapted with permission from ACS [28].
a, b-down-right
