Scalable Fabrication of Metal Oxide Nanofibers for Advanced Electronic Circuits and Smart Sensors

Conspectus Metal oxide semiconductor nanofibers (MO NFs) combine the electronic properties of MO semiconductors with the high surface area and one-dimensional architecture of nanofibers. With appropriate composition and network design, MO NFs can complement conventional thin films by offering directional charge transport in aligned networks, mechanical flexibility, and enhanced sensitivity to external stimuli. Their open, porous networks expose a large fraction of the semiconductor surface, enabling gas adsorption and electrolyte interactions to modulate electrical transport within the channel. Realizing these benefits in practical devices requires scalable fabrication routes that preserve the desired material and network characteristics. Conventional routes to MO nanostructures, including chemical vapor deposition and hydrothermal synthesis, can involve specialized equipment or extended processing. To this end, alternative fabrication methodologies, such as electrospinning, blow-spinning, and template-assisted methods, are being developed to enable scalable and efficient production of MO NFs for transistors, gas sensors, wearable electronics, neuromorphic devices, and autonomous environmental monitoring systems. This Account follows the development of MO NF networks from fabrication to integrated electronic and sensing systems, drawing particularly on our works with indium gallium zinc oxide (IGZO), CuO, and indium tin oxide (ITO) NFs. These material systems provide complementary functions, ranging from gate-controlled semiconductor channels to resistive sensing elements. We first compare electrospinning (including aligned electrospinning), blow-spinning, and nanofiber-assisted methods, emphasizing how precursor chemistry, alignment, network uniformity, and thermal processing influence material properties and device performance. The template-assisted approaches illustrate how preformed polymer fibers can serve as masks or scaffolds for oxide patterning and deposition. We then examine how composition, fiber continuity, and interfacial coupling govern transistor performance with particular attention to electrolyte-gated operation and low-voltage logic circuits. The discussion extends to neuromorphic devices in which defect-mediated conductance modulation and interfacial effects support synaptic plasticity, artificial-neural-network inference, and reservoir computing. Electrical and optical stimulation provide complementary means of programming these responses. We highlight how persistent conductance states enable weight storage, whereas transient relaxation supports the processing of time-dependent signals. Finally, we trace the progression from room-temperature NO2 sensing to wireless respiratory monitoring, multimodal wearable platforms, and autonomous gas-source localization. These demonstrations show how responses to chemical, optical, thermal, and mechanical stimuli can be coupled with readout circuits, wireless communication, and robotic control to realize application-specific systems. Although MO NF transistors still face challenges in high-density integration, their porous and accessible networks offer distinctive opportunities for transistor-based and resistive gas sensors. We conclude by discussing reproducible fabrication, operational reliability, sensing selectivity, and low-power integration as priorities for the further development of practical MO NF technologies.