The bionic science and robotic science have obtained the artificial electronics human sensory organs such as electronic skins (E-skins), electronic nose (E-nose), and electronic tongue (E-tongue) to sense the physical and chemical environment. Being one of the building blocks, gas sensors have crucial importance in the field of environmental monitoring, health safety, agriculture, military applications, food chains, and process industries. To implement the laboratory grade sensors with internet of things (IoT) technology, wearable devices (flexible and miniaturized) are studied innovatively and extensively. In view of this the gas sensors based on 1D nanostructures, such as nanowires (NWs), nanotubes (NTs), nanorods (NRs), and nanofibers (NFs) have drawn significant attention. Among these, NFs have large specific surface area as well as high porosity to accelerate the gas diffusion. It further enhances the electric charge transport due to the fibrous reticular structure by providing the chemically reactive sites on the adsorption area. Although conventional inorganic nanomaterials are being highly sensitive, they are not flexible in order to tune the sensor characteristics in pristine forms. To overcome this, attention is being provided to new class of nanomaterials, i.e. organic–inorganic nanohybrids wherein organic or soft nanomaterials are employed as a matrix or in hybrid forms. These materials are becoming promising candidates to achieve the lower or near room-temperature operations of gas sensors. Besides, NFs have potential to overcome several challenges such as portability, durability, and flexible electronics.

Recently, the single-NF-based sensors demonstrated its ability to rapid capture, diffuse, and release of gas molecules and have been looked upon to realize ultrasensitive room-temperature gas sensors. To achieve the commercially deployable sensor fulfilling the 4-S sensor selection criteria, understanding of the interfacial properties in nanohybrids and the governing sensing mechanism are a must. The present chapter provides a brief overview of organic–inorganic NFs-based sensors for near or room-temperature-sensing application. The chapter aims to provide elaborate survey of the nanomaterials that fulfills the need of ultrasensitive and ultra-power saving gas sensor devices, which is useful to academics, R&D, and scientific communities. Additionally, the classification and working principles of the heterostructures of NFs are described and discussed elaborately. Different approaches to engineer the surface as well as interface of nanohybrids such as p–n or Schottky heterojunctions and their role in improving the sensor performance are extensively discussed taking help from the literature and some of our recent findings. Finally, some of the daunting challenges that need to be addressed to achieve a completely commercially viable product are discussed along with the possible solutions.