CNT/organic probe-based chemiresistive sensors suffer
from the
problem of low sensitivity and poor stability due to the unstable
and unfavorable CNT/organic probe interface. A new designing strategy
of a one-dimensional van der Waals heterostructure was developed for
ultrasensitive vapor sensing. By modifying the perylene diimide molecule
at the bay region with phenoxyl and further Boc-NH- phenoxy side chains,
a highly stable 1D VDW heterostructure SWCNT-probe molecule system
was formed with ultrasensitivity and specificity. Interfacial recognition
sites consisting of SWCNT and the probe molecule are responsible for
the synergistical and excellent sensing response to MPEA molecules,
which was proved by Raman, XPS, and FTIR characterizations together
with dynamic simulation. Based on such a sensitive and stable VDW
heterostructure system, the measured detection limit reached as low
as 3.6 ppt for the synthetic drug analogue N-methylphenethylimine
(MPEA) in the vapor phase, and the sensor showed almost no performance
degradation even after 10 days. Furthermore, a miniaturized detector
was developed for real-time monitoring of drug vapor detection.