Textile Impedentiometric Sensor for Gas Detection

Gas sensing has been drawing attention over the years in terms of environmental remediation and health diagnostic potential. Volatile organic compounds (VOCs) qualitative/quantitative monitoring is indicative of air quality and people health status. However, VOC analysis is often performed by means of expensive and time-consuming lab-based equipment. Thus, this study proposes the fabrication and characterization steps for the development of a simple, eco-friendly and relatively inexpensive gas impedentiometric sensor. The sensing layer is comprised of gold nanoparticles (AuNPs) obtained from gold tetra chloric acid (HAuCl4) and sodium citrate by means of a green synthesis approach. The analyte under investigation is acetone, one of the principal breath volatiles, also reported by plenty of studies as a potential biomarker of various diseases. Cotton textiles, with specific texture and grammage, were used as substrate. Conductive traces over the samples were patterned either with carbon/8B pencil or with a stencil-applied conductive ink. The sensor working principle is predicated on the correlation between substrate impedance changes and Van der Waals interactions between acetone and citrate-functionalized AuNPs. Charge injection and transport processes originating from acetone adsorption on the sensor reflected electrical properties variation. Impedance magnitude for the pristine sample turned out to be around 1010 Ω, while AuNPs functionalization brought impedance down to 107 Ω range. On the other hand, when acetone was dripped on the sensor, a two orders of magnitude variation (from 107 Ω to 105 Ω) was observed. Hence, the sensor can be considered amenable to acetone detection by means of functionalized textiles.