Recent Advances in Gas Detection Methodologies with a Special Focus on Environmental Sensing and Health Monitoring ApplicationsA Critical Review

With the expansion of the Internet-of-Things (IoT), theuse ofgas sensors in the field of wearable technology, smart devices, andsmart homes has increased manifold. These gas sensors have two keyapplications one is the detection of gases present in the environmentand the other is the detection of Volatile Organic Compounds (VOCs)that are found in the breath. In this review, we focus systematicallyon the advancements in the field of various spectroscopic methodssuch as mass spectrometry-based analysis and point-of-care approachto detect VOCs and gases for environmental monitoring and diseasediagnosis. Additionally, we highlight the development of smart sensorsthat work on the principle of electrochemical detection and provideexamples of the same through an extensive literature review. At theend of this review, we highlight various challenges and future perspectives.