ZIF-8/MWCNT-nanocomposite based-resistive sensor for highly selective detection of acetone in parts-per-billion: Potential noninvasive diagnosis of diabetes

Zeolitic imidazolate framework-8 (ZIF-8) is a promising metal-organic framework for gas sensing applications in humid conditions due to its inherent hydrophobicity. However, its low sorption capacity for alcohols and acetone at room temperature and atmospheric pressure limits its applications. To overcome this, a novel composite of ZIF-8 and bare multiwall-carbon-nanotubes (MWCNTs) was developed, significantly enhancing its sorption capacity for alcohols and acetone. A ZIF-8/MWCNT-coated quartz crystal microbalance (QCM) sensor successfully detected these volatile organic compounds (VOCs) at 0.62 parts-per-million (ppm) under ambient conditions, a marked improvement over ZIF-8 alone. However, selectivity towards acetone, a crucial biomarker for diabetes, is lacking when other VOCs are present. This study investigates the effect of different sensing platforms with varying response mechanisms on achieving high selectivity for acetone using a ZIF-8/MWCNT-coated QCM and a chemiresistive sensor. The chemiresistive-sensor demonstrated excellent acetone detection performance, with high selectivity, low humidity response, good repeatability, complete reversibility, and rapid response. Remarkably, it achieved a limit of detection of 1.7 parts-per-billion (ppb) at ambient conditions, three orders of magnitude lower than the concentration in the exhaled breath of diabetic patients (1.8 ppm). This breakthrough highlights the high potential of the sensor for diabetes diagnosis and monitoring through breath analysis.