Nanostructured polyaniline-based composites for ppb range ammonia sensing

vQRS Based on Hybrids of CNT with PMMA-POSS and PS-POSS Copolymers to Reach the Sub-PPM Detection of Ammonia and Formaldehyde at Room Temperature Despite Moisture

“…The limit of concentration of short term exposure to ammonia is 50 ppm for 30 min [10], while for longer times it is only 20 ppm. Classical ammonia sensors are mainly based on metal oxides (MOx) [11], intrinsically-conducting polymers (ICP) [12], catalytic sensors [13], and spectrophotometric detection [14]. Nevertheless, the detection of ammonia at the sub-ppm level remains challenging for most of these sensors, which require high temperatures to activate, react with ammonia molecules, or eliminate moisture [15,16].…”

“…Nevertheless, the detection of ammonia at the sub-ppm level remains challenging for most of these sensors, which require high temperatures to activate, react with ammonia molecules, or eliminate moisture [15,16]. Additionally, ICP-based sensors can lack reproducibility due to the dependency of their responses' amplitude on several parameters, such as the active layer thickness and morphology, its porosity, the nature of the dopant, and the presence of other components in the material [12]. Several works also mention the use of carbon nanotube-based sensors for the detection of ammonia [17][18][19], but CNTs without functionalization have poor chemical selectivity [20] and the resulting conducting architecture tends to have a poor structural stability when assembled without any binder or matrix [21].…”

“…However, it seems that reaching the ppb range of detection makes the use of nanostructured transducers compulsory, as only the few works using this strategy report such a high sensitivity. Wojkiewicz et al [12] synthesized three kinds of nanostructured thin transducing films, from the assembly of poly(butadiene) (PBuA-PANI), poly(vinyl fluoride) (PVDF-PANI) core/shell nanoparticles, and PANI (CSA) nanofibers filled poly(urethane) films, demonstrating their ability to detect, respectively, 250, 100, and 20 ppb of NH3. Moreover, the chemo-resistive signals of these systems are found to be reproducible and with low noise, but their recovery time is long (more than 20 min), compared to the exposure time of analytes of 5 min.…”

“…From this non-exhaustive overview on the different strategies used to sense CH 2 O and NH 3 at the very low concentration at which they are toxic, i.e., the sub-ppm level, the best results were obtained with MOx- [49] or ICP-based [12] nanostructured resistive sensors. However, it can also be concluded that there is still a challenge to develop vapour sensors: highly-sensitive and -selective to CH 2 O and NH 3 , operating at room temperature to minimize consumption, working in high moisture environments, and easily up-scalable into e-nose applications.…”

Ammonia quantitative analysis model based on miniaturized Al ionization gas sensor and non-linear bistable dynamic model

“…[1][2][3] Many researchers develop novel materials to fabricate ammonia gas sensors. [4][5][6][7][8][9][10][11][12][13] Since the discovery of the catalytic effect of SnO2 in 1962, many studies have been conducted to improve sensor's functions. 14,15 Since proposed by Benzi in 1981 for the earth ice age disciplinarian explanation, 16 bistable dynamic model has been widely applied in fields, such as signal detection, electrical circuits, biological modeling, neural systems, et al [17][18][19][20] It is interesting that, under certain circumstances, an extra dose of noise can actually help the performance of some devices, by eliminating the internal noise in the system.…”