Author ORCID Identifier
0009-0005-4751-6113
Biosketch
K. Sri Varshini is a researcher specializing in nanomaterials and chemical sensing technologies, with a strong focus on environmental monitoring applications. She completed her Bachelor’s degree in Physics with distinction and has pursued advanced research in the development of functional nanostructures for gas sensing.Her doctoral work focuses on enhanced vapour detection using electrospun metal-oxide nanofibers for indoor air quality monitoring, particularly in paint industry applications.
Her research involves the fabrication and optimization of sensing elements capable of detecting volatile organic compounds such as ammonia, formaldehyde, and toluene. By employing electrospinning techniques, she has developed nanofiber-based sensors that exhibit promising sensitivity and selectivity toward hazardous vapours. These sensing elements are designed to provide efficient and reliable detection, contributing to safer industrial environments.
Her work highlights the potential of metal-oxide nanofibers as effective sensing materials for real-time air quality assessment. She is particularly interested in improving sensor performance through material innovation and device optimization. K. Sri Varshini continues to focus on developing practical and scalable sensing technologies that address critical challenges in environmental and industrial monitoring.
Date of Award
12-3-2025
Document Type
Thesis
School
School of Electrical & Electroncis Engineering
Programme
Ph.D.-Doctoral of Philosophy
First Advisor
Dr.D.Balamurugan
Keywords
Nanofibers, Electrospinning, Gas sensor, Chemiresistive method, Quick response
Abstract
The objective of this work is to fabricate metal oxide-based nanofibers, which helps in monitoring indoor air quality, which is deteriorating due to VOCs like Formaldehyde, Toluene, and Ammonia, commonly found in paints, plywood, and adhesives. Prolonged exposure to these VOCs can affect the respiratory and nervous system. They are classified as carcinogens by the IARC.
Based on the analysis, this work was framed to deposit Fe2O3, NiO, and ZnO/Fe2O3 as well ZnO/NiO and Fe2O3/NiO nanofibers on the glass substrate through horizontal electrospinning method. The obtained nanofibers are vacuum annealed at 50 ℃ for 30 mins to remove the water content, then followed by calcination with 450 ℃ for 12 hr that helps to remove the volatile components, as well as to obtain the porous structure of metal-oxide nanofibers.
Calcinated nanofibers were undergone for the following studies, which are compositional, structural, morphological, thermal, and electrical analyses. The vapour/gas detection studies of fabricated sensing elements were carried out in a home-built sensing chamber. The continuous and bead-less formation of nanofibers were achieved with the optimized deposition parameters. The polycrystalline structure and purity of Fe2O3 and NiO were confirmed through XRD and XPS. Maintaining the arrangement of nanograins in one-dimensional structures ensures a high surface-to-volume ratio and a porous nature, which significantly enhances vapor/gas sensing capabilities. As a result, at 300 ℃, Fe2O3 ii nanograins showed a better response towards ammonia. Similarly, at 300 ℃, NiO nanograins showed a better response towards formaldehyde. Both films exhibit a detection range of 5–500 ppm for the targeted vapor. The sensitivity of Fe2O3 and NiO nanofibers was enhanced by incorporating the effect of ZnO.
ZnO/Fe2O3 and ZnO/NiO show randomly oriented multi-junction nanofibers, which were uniformly distributed. Even after the calcination process, the alignment of the nanograins along the nanofibers are maintained, resulting in a high surface-to-volume ratio characteristic for gas sensing applications. ZnO/Fe2O3 exhibited an improved response towards formaldehyde at 300 ℃ while ZnO/NiO showed better sensitivity towards at an operating temperature at 350 ℃.
Meanwhile, the range of detection also increased from 5 ppm to 0.5 ppm compared to bare materials. When the bare materials were combined (Fe2O3/NiO), it showed better response towards toluene while maintaining the operating temperature at 350 ℃. The lower limit of detection is further increased to 0.1 ppm. From these results, it is identified that the prepared sensing elements are highly preferable for the detection of VOCs utilized in paint industries
Recommended Citation
K, Sri Varshini Ms, "Enhanced Vapour Detection Through Electrospun Metal-Oxide Nanofibers" (2025). Theses and Dissertations. 200.
https://knowledgeconnect.sastra.edu/theses/200