Acetone Gas Sensor Based on SWCNT/Polypyrrole/Phenyllactic Acid Nanocomposite with High Sensitivity and Humidity Stability

Abstract

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.

Flexible Sensor Film Based on Rod-Shaped SWCNT-Polypyrrole Nanocomposite for Acetone Gas Detection

“…This resulted in the formation of a rod-shaped nanostructure with SWCNT at the core surrounded by PPy–PLA ( Scheme 1 ). A previous study reported that PLA is chemically bonded with the PPy chain and reacts selectively with a specific gas such as acetone [ 26 ]. The resulting products can maintain long-term dispersion stability in aqueous solution without precipitation due to its excellent dispersion characteristics.…”

“…The rod-shaped SWCNT/C4F-PPy nanocomposite was synthesized using an emulsion polymerization technique described in a previous paper [ 26 ]. The synthesis proceeded in five steps.…”

“…Recently, flexible gas sensors [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ] based on plastic substrates, such as polyimide (PI) [ 12 , 13 , 21 ], polycarbonate (PC) [ 16 ], and polyethylene terephthalate (PET) [ 20 , 21 , 22 , 23 ] films have been developed to achieve lower manufacturing costs as well as improved miniaturization, portability, and wearability. In addition, gas sensors that use π-conjugated carbon compounds (CCC), such as carbon nanotube (CNT) [ 20 , 21 , 22 , 23 ], polypyrrole (PPy) [ 17 , 24 , 25 , 26 ], polyaniline (PANi) [ 18 , 27 , 28 ], and graphite [ 29 ], as a gas-sensing layer are being actively studied. These CCC-based sensors exhibit improved features for gas detection [ 15 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ].…”

“…In addition, gas sensors that use π-conjugated carbon compounds (CCC), such as carbon nanotube (CNT) [ 20 , 21 , 22 , 23 ], polypyrrole (PPy) [ 17 , 24 , 25 , 26 ], polyaniline (PANi) [ 18 , 27 , 28 ], and graphite [ 29 ], as a gas-sensing layer are being actively studied. These CCC-based sensors exhibit improved features for gas detection [ 15 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ]. They operate at low temperatures and the sensing material can be designed to detect selected compounds with a very low response to other compounds.…”

Highly sensitive acetone sensor based on conjugated polymer nanocomposites

“…The polymer as well as polymer nanocomposite sensors prepared showed excellent linearity with gas concentration because of the increased electron hopping by the addition of Fe 2 O 3 and Co‐Fe 2 O 3 nanoparticles. Better sensing response shown by the copolymer nanocomposites compared to the pure polypyrrole can be attributed to the increased number of positive charges (polarons or bipolarons) on the polymer backbone 33 …”