Executive Summary : | Non-alcoholic fatty liver disease (NAFLD) is a metabolic disorder that is becoming increasingly prevalent worldwide. It can lead to inflammation, fibrosis, cirrhosis, and liver cancer. Early detection of NAFLD is essential for timely intervention and effective treatment to avoid the further complications mentioned above. However, current diagnostic methods for NAFLD are invasive, expensive, and require sophisticated equipment and specialized (trained) manpower. As a result, there is a critical need for non-invasive and user-friendly diagnostic tools for point-of-care diagnosis of NAFLD. Breath analysis is an emerging field that has shown great potential in diagnosing various diseases like asthma, lung cancer etc. [1-3]. This approach relies on detecting specific volatile organic compounds (VOCs) in very trace amount in exhaled breath that are considered as biomarkers of that diseases. Analyzing breath VOCs provides a non-invasive and convenient way to detect various diseases. This project aims to develop a gas/vapor sensor array for detecting NAFLD by analyzing breath samples. The device will consist of five gas/vapor sensors, each being selective to a specific VOC (biomarker) for NAFLD detection, namely acetone, isoprene, trimethylamine, pentane, and acetaldehyde. These VOCs are known to be produced or their concentration increases for the patients suffering from NAFLD (while for healthy persons these VOCs are either absent or their concentration is imperceptible (low ppb)) making them excellent biomarkers for diagnosis. This project will focus on developing a heterojunction gas/vapor sensor device (array) using 2D materials such as Graphene Oxide (GO), Reduced Graphene Oxide (rGO), Molybdenum Disulphide (MoS2) and Tungsten disulphide (WS2). 2D junction offers depletion region which will be fully depleted in absence of target gas while there will be a huge change in junction depletion region width in presence of these target VOCs leading to impressive change in the corresponding junction resistance/capacitance change and hence high sensitivity and low detection level (essential requirement for this specific application) will be achievable. Surface functionalization by metal dopants, further tuning of functional groups by controlled oxidation using varying thickness and junction area in p-n heterojunction devices will lead to tunable capacitance. Through tuning capacitance, optimum frequency for sensing a particular species can be changed and selectivity can also be improved. The signal output will be processed using signal processing circuits and transmitted to display devices such as monitors or mobile phones, estimating the content of each biomarker to detect the presence of NAFLD. A prototype with complete instrumentation, including the gas sensor array and signal processing unit, will be developed for market-ready use. |