This article provides a comprehensive review of recent (2008 and 2009) progress in gas sensors based on semiconducting metal oxide one-dimensional (1D) nanostructures. During last few years, gas sensors based on semiconducting oxide 1D nanostructures have been widely investigated. Additionally, modified or doped oxide nanowires/nanobelts have also been synthesized and used for gas sensor applications. Moreover, novel device structures such as electronic noses and low power consumption self-heated gas sensors have been invented and their gas sensing performance has also been evaluated. Finally, we also point out some challenges for future investigation and practical application.

A novel photo-electronic hybrid-integrated synaptic device based on a 2D MoS₂ phototransistor gated by the electric-double-layer biopolymer electrolyte (sodium alginate) is proposed.

This article reviews the recent progress in the field of electric-double-layer transistors for synaptic devices and neuromorphic systems.