Muthukumar Murugesan, S.R. Meher
The polymorphic phase of TiO 2 -based chemiresistive sensors represents an exciting area of research that has captured the attention of scientists due to its remarkable ability to tailor physico-chemical properties through various approaches. These sensors are not only reliable and cost-effective but also have the potential to produce compact devices that seamlessly combine efficiency with elegance. Their versatility serves as a platform for innovation, paving the way for advances in sensing technology, such as environmental monitoring and healthcare diagnostic applications. The practical applications of pristine TiO 2 have been constrained due to several factors, including suboptimal selectivity, inadequate sensor response, low detection limits, and interference from relative humidity. Consequently, this review endeavours to establish a foundational framework for enhancing the sensing performance of gas sensors through both chemical and physical modification strategies. It offers insights into the fundamental properties and sensing mechanisms of chemiresistive gas sensors, as well as the characteristics of anatase, rutile, and their mixtures, whether in the form of thin films or nanomaterials. Ultimately, this review aims to serve as a comprehensive roadmap for the development of compact, high-performance chemiresistive gas sensors that leverage TiO 2 polymorph in the form of thin film and nanomaterials.