Smartphone-based detection of lung cancer-related volatile organic compounds (VOCs) using rapid synthesized ZnO nanosheet

Point of care (POC) determination of volatile organic compounds (VOCs) in the ppb level is essential for non-invasive diagnosis applications. Chemical sensors are promising options to monitor VOCs in exhaled breath as disease biomarkers. Gas sensors based on nanostructured ZnO have received significant attention because of their advantages in enhancing gas sensing performance. In this study, a simple direct method is introduced for the rapid synthesis of zinc oxide nanosheet, and its application to fabricate a susceptible sensitive, smartphone-based resistive gas sensor for measurement of VOCs, that, are considered as lung cancer biomarkers. Zinc foil was anodized in KNO3 aqueous electrolyte at room temperature to synthesize nanosheets with approximate widths of 24 nm. The fabricated chemiresistive gas sensor using the synthesized ZnO nanosheet structure showed high sensitivity to measure VOCs such as diethyl ketone, acetone, and Isopropanol. An Arduino Uno with a Bluetooth module was used to read the fabricated ZnO-based sensor and send data to a smartphone. The smartphone-based chemiresistor device exhibited a high response to a low concentration of lung cancer-related volatile organic compounds. High humidity and the presence of hexane, ammonia, and carbon dioxide in the sensor environment didn't affect the sensor response. The fabricated devices have the potential for non-invasive diagnosis of lung cancer in the early stage by analyzing relative biomarkers in exhaled breath.