Advancements in wearable ammonia sensors using polypyrrole/MWCNT coated yarn

Abstract

In this study, we utilized a dip coating method to modify insulating yarn with polypyrrole and multiwall carbon nanotubes (MWCNTs) to convert it into a conductive yarn. The resulting fabricated conducting yarn underwent thorough characterization through scanning electron microscope, x-ray diffraction pattern, and thermal gravimetric analysis. Subsequently, we examined the ammonia sensing properties of the modified yarn at various stages of its development. Our findings revealed that the combination of MWCNTs followed by polypyrrole modification significantly enhanced the ammonia sensing capabilities compared to using MWCNTs or polypyrrole-coated yarn individually. Specifically, the MWCNTs followed by polypyrrole modified yarn demonstrated an excellent sensing response, remarkable repeatability (up to 24 continuous cycles), quick response time (11 ± 2 s), and recovery time (34 ± 5 s). Additionally, the sensor exhibited good linearity in detecting ammonia vapor concentrations within the range of 20-100 ppm. We also assessed the sensor’s performance with diverse vapors at room temperature, revealing its high selectivity for ammonia. Furthermore, the sensor’s response correlated linearly with yarn length. Remarkably, it demonstrated minimal sensitivity to humidity and exceptional stability over fifty days. These results have the potential to lead to the development of wearable room temperature ammonia sensors, suitable for use in agricultural and industrial chemistry, as well as in environmental, automotive, and medical applications.