RESUMO
A nanocomposite rod-shaped structure with a single-walled carbon nanotube (SWCNT) embedded in polypyrrole (PPy) doped with nonafluorobutanesulfonic acid (C4F), SWCNT/C4F-PPy, was synthesized using emulsion polymerization. The hybrid ink was then directly coated on a polyimide film interdigitated with the Cu/Ni/Au electrodes via a screen-printing technique to create a flexible film sensor. The sensor film showed a response of 1.72% at 25 °C/atmospheric pressure when acetone gas of 5 ppm was injected, which corresponds to almost 95% compared to the Si wafer-based array interdigitated with the Au electrode. Additionally, C4F was used as a hydrophobic dopant of PPy to improve the stability of humidity and to produce a highly sensitive film-type gas sensor that provides stable detection even in humid conditions.
RESUMO
Core-shell-shaped nanoparticles (CSS-NPs) with polyaniline emeraldine salts (PANi) in the core and hydroxypropyl methylcellulose (HPMC) and heptadecafluorooctanesulfonic acid (C8F) shells, i.e., C8F-doped PANi@HPMC CSS-NPs, were synthesized as a gaseous acetone sensing material with high sensitivity and humidity stability. The HPMC was chemically combined on the positively charged PANi NPs' outer surface, allowing it to efficiently detect acetone gas at concentrations as low as 50 ppb at 25 °C. To impart humidity stability, C8F was employed as a hydrophobic dopant, and a valid signal could be reliably detected even in the range of 0-80% relative humidity. The sensing material's structural analysis was conducted using scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and infrared spectroscopy, and in particular, the reaction mechanism with acetone gas was detected through a spectroscopic method. Thus, these findings illustrate the potential as a novel sensing material to detect acetone gas at a trace level of less than 1 ppm in human respiratory gas.
RESUMO
We synthesized core-shell-shaped nanocomposites composed of a single-walled carbon nanotube (SWCNT) and heptadecafluorooctanesulfonic acid-doped polypyrrole (C8F-doped-PPy)/phenyllatic acid (PLA), i.e., C8F-doped-PPy/PLA@SWCNT, for detecting acetone gas with high sensitivity and humidity stability. The obtained nanocomposites have the structural features of a sensing material as a C8F-doped-PPy layer surrounding a single-stranded SWCNT, and a PLA layer on the outer surface of the PPy as a specific sensing layer for acetone. PLA was chemically combined with the positively charged PPy backbone and provided the ability to reliably detect acetone gas at concentrations as low as 50 ppb even at 25 °C, which is required for medical diagnoses via human breath analysis. When C8F was contained in the pyrrole monomer in a ratio of 0.1 mol, it was able to stably detect an effective signal in a relative humidity (RH) of 0-80% range.
