Contents


Preface

Gas sensors have become a highly researched area because they can detect and recognize different types of toxic gases and low concentrations of vapor compounds. This interest in gas sensing has attracted worldwide interest, because of several diverse applications. Nowadays, there are many tools and materials that can be employed to design a gas sensor system. However, improvements in gas sensing system performance have been substantially correlated with advances in nanotechnology. This book focuses on the fabrication and application of gas sensing systems. It covers the recent developments of different materials used to design gas sensors, such as conducting polymers, semiconductors, as well as layered and nanosized materials. The widespread applications of various gas sensors for the detection of gaseous compounds are also discussed. The book provides an overview of recent attributes of gas sensors and their applications to a broad audience, including beginners, graduate students, and specialists in both academic and industrial sectors. It contains seven chapters that describe the design, fabrication, different uses, applications, and attributes of gas sensors. The first chapter is related to metal oxide gas sensors such as ZnO and multiwalled carbon nanotubes as well as their composites. It describes the performance of fabricated sensors for sensing NO2, NH3, and CO gases. The second chapter discusses the design of microgas sensors using radiometric phenomena, which occurs due to the temperature difference in rarefied gases. The effects of primary factors and parameters are also described. The third chapter presents terahertz wave propagation in layered media based on waveguide and artificial material configurations to sense gas molecules, especially volatile organic compounds. Improvement in detection sensitivity and selectivity is also discussed with the aid of multilayer microporous polymer structures as a terahertz artificial material to adsorb vapor molecules. The fourth chapter is related to a review of the preparation of ZnO nanorods and their use in ethanol vapor sensing, where the efficiency of 1D ZnO nanostructures prepared by different techniques as a sensing material for gaseous compounds, especially ethanol, is discussed. Ethanol detection characteristics using a ZnO sensor reveals its efficiency in terms of electrical resistance, capacitance, and impedance. The fifth chapter describes the design and fabrication of films based on metal oxide materials for petroleum vaporous compounds. The sixth chapter discusses the synthesis and sensing mechanisms of different toxic chemicals using ZnO nanowire materials synthesized by thermal evaporation through a vapor transport method using a vapor liquid solid mechanism. The chapter also reveals the sensing performance of ZnO nanowires for CH4 gas with high sensitivity. The seventh chapter describes the contribution of conducting polymers as effective sensing materials to enhance their sensitivity, selectivity,

and stability to detect gaseous compounds.

**Sher Bahadar Khan, Abdullah M. Asiri and Kalsoom Akhtar**

King Abdulaziz University,

Saudi Arabia
