Zinc Oxide-Based Acetone Gas Sensors for Breath Analysis: A Review.

Acetone is one of the toxic, explosive, and harmful gases. It may cause several health hazard issues such as narcosis, headache, etc. Acetone is also regarded as a key biomarker gas to diagnose several diseases as well as monitor the disorders in human health. Based on clinical findings, acetone concentration in human breath is correlated with many diseases such as asthma, halitosis, lung cancer, and diabetes. Thus, its investigation can become a new approach for health monitoring. Better management in the early stages of such diseases has the potential not to reduce deaths associated with the disease but also reduce medical costs. ZnO-based sensors show great potential for acetone gas due to its high chemical stability, simple synthesis process, and low cost. Findings suggested that the acetone sensing performance of such sensors can be significantly improved by manipulating microstructure (surface area, porosity, etc.), composition, and morphology of ZnO nanomaterials. This article provides a comprehensive review of the-state-of-the-art research activities, published during last five years (2016 to 2020), related to acetone gas sensing using ZnO. It focuses on different types of nanostructured ZnO-based acetone gas sensors. Proper engineering of ZnO structural properties has to lead to the detection of acetone at 5 ppb level with excellent selectivity and reproducibility at an operating temperature of 150 0 C.