1 research outputs found
Pulse-Driven Capacitive Lead Ion Detection with Reduced Graphene Oxide Field-Effect Transistor Integrated with an Analyzing Device for Rapid Water Quality Monitoring
Rapid
and real-time detection of heavy metals in water with a portable
microsystem is a growing demand in the field of environmental monitoring,
food safety, and future cyber-physical infrastructure. Here, we report
a novel ultrasensitive pulse-driven capacitance-based lead ion sensor
using self-assembled graphene oxide (GO) monolayer deposition strategy
to recognize the heavy metal ions in water. The overall field-effect
transistor (FET) structure consists of a thermally reduced graphene
oxide (rGO) channel with a thin layer of Al<sub>2</sub>O<sub>3</sub> passivation as a top gate combined with sputtered gold nanoparticles
that link with the glutathione (GSH) probe to attract Pb<sup>2+</sup> ions in water. Using a preprogrammed microcontroller, chemo-capacitance
based detection of lead ions has been demonstrated with this FET sensor.
With a rapid response (∼1–2 s) and negligible signal
drift, a limit of detection (LOD) < 1 ppb and excellent selectivity
(with a sensitivity to lead ions 1 order of magnitude higher than
that of interfering ions) can be achieved for Pb<sup>2+</sup> measurements.
The overall assay time (∼10 s) for background water stabilization
followed by lead ion testing and calculation is much shorter than
common FET resistance/current measurements (∼minutes) and other
conventional methods, such as optical and inductively coupled plasma
methods (∼hours). An approximate linear operational range (5–20
ppb) around 15 ppb (the maximum contaminant limit by US Environmental
Protection Agency (EPA) for lead in drinking water) makes it especially
suitable for drinking water quality monitoring. The validity of the
pulse method is confirmed by quantifying Pb<sup>2+</sup> in various
real water samples such as tap, lake, and river water with an accuracy
∼75%. This capacitance measurement strategy is promising and
can be readily extended to various FET-based sensor devices for other
targets