A calibrated graphene-based chemi-sensor for sub parts-per-million NO2 detection operating at room temperature

Abstract

Here, we present a room temperature operating chemi-sensor based on a graphene film that shows sensitivity to NO2 up to a 50 parts-per-billion (ppb) with extremely limited interference from relative humidity and can be also calibrated in a sub-parts-per-million (ppm) range with a response and recovery time of few seconds. The device has been fabricated using as active material, a solution of graphene nanosheets suspended in N-methyl-pyrrolidone drop casted on an alumina substrate with gold interdigitated electrodes. The derivative of the device response is found to be univocally correlated to NO2 concentrations from 100 ppb up to 1000 ppb and the sensor can therefore be calibrated in this same range.

Graphene-based Schottky Device Detecting NH3 at ppm level in Environmental Conditions

“…The shape and position of the peaks indicate that the graphite is exfoliated down to less than five layers, as discussed in detail in ref [6]. The electrical characterizations performed on the structure confirmed a rectifying behavior with the formation of a Schottky barrier at the graphene/Si interface.…”

“…The graphene was analyzed by Micro Raman Spectroscopy through a Renishaw inVia Reflex apparatus. All Raman spectra were captured in backscattering configuration (λ=514.5 nm) with a 100x objective on SiO 2 /Si substrate [6]. The sensing tests were performed in a Gas Sensor Characterization System (Kenosistec) by keeping Relative Humidity (RH) and temperature at constant values of 50% and 295 K [6].…”

A simple method to recover the graphene-based chemi-resistor signal

“…The standard exposure protocol adopted for each measurement consists basically of three steps: (a) the baseline, during which only the carrier gas is fluxed with the aim of stabilizing the current; (b) the exposure window to the target gas; and (c) the recovery phase, during which the analyte flow is stopped and again only the carrier gas is fluxed in order to return the device to the initial conditions (Figs. 1-2) Ricciardella et al, 2014). The devices were tested at three different steps: as soon as prepared, after about one month, during which they were exposed in air, and finally after applying the two described restoring methods, namely the device annealing at 130 • C in vacuum for 120 min and the newly developed method that encompasses the dipping of exhaust devices into ultrapure water at 100 • C for 60 s, followed by a drying step on the hot plate at 150 • C for 5 min.…”

Chili Pepper Scent: Study and Recognition with Chemiresistors Array

“…We choose max relative response velocity instead of percentage relative response because we have reason to believe [8] that this differential parameter is less affected by sensors drifting, and saturation although it contains the same discrimination feature of the Sensor Response.…”