Rapid development of artificial intelligence techniques ignites the emerging demand on accurate perception and understanding of optical signals from external environments via brain-like visual systems. Here, enabled by quasi–two-dimensional electron gases (quasi-2DEGs) in InGaO₃(ZnO)₃ superlattice nanowires (NWs), an artificial visual system was built to mimic the human ones. This system is based on an unreported device concept combining coexistence of oxygen adsorption-desorption kinetics on NW surface and strong carrier quantum-confinement effects in superlattice core, to resemble the biological Ca²⁺ ion flux and neurotransmitter release dynamics. Given outstanding mobility and sensitivity of superlattice NWs, an ultralow energy consumption down to subfemtojoule per synaptic event is realized in quasi-2DEG synapses, which rivals that of biological synapses and now available synapse-inspired electronics. A flexible quasi-2DEG artificial visual system is demonstrated to simultaneously perform high-performance light detection, brain-like information processing, nonvolatile charge retention, in situ multibit-level memory, orientation selectivity, and image memorizing.

During the past two decades, one–dimensional (1D) metal–oxide nanowire (NW)-based molecular sensors have been witnessed as promising candidates to electrically detect volatile organic compounds (VOCs) due to their high surface to volume ratio, single crystallinity, and well-defined crystal orientations. Furthermore, these unique physical/chemical features allow the integrated sensor electronics to work with a long-term stability, ultra-low power consumption, and miniature device size, which promote the fast development of “trillion sensor electronics” for Internet of things (IoT) applications. This review gives a comprehensive overview of the recent studies and achievements in 1D metal–oxide nanowire synthesis, sensor device fabrication, sensing material functionalization, and sensing mechanisms. In addition, some critical issues that impede the practical application of the 1D metal–oxide nanowire-based sensor electronics, including selectivity, long-term stability, and low power consumption, will be highlighted. Finally, we give a prospective account of the remaining issues toward the laboratory-to-market transformation of the 1D nanostructure-based sensor electronics.

Catalysis-based electrical sensing of volatile organic compounds on metal oxide surfaces is a powerful method for molecular discrimination. However, catalyst deactivation caused by the poisoning of catalytic sites by analytes and/or catalyzed products remains a challenge. This study highlights the underestimated role of van der Waals interactions between hydrophobic aliphatic alkyl chains and hydrophilic ZnO surfaces in mitigating catalyst deactivation during aliphatic aldehyde sensing. By immobilizing octadecylphosphonic acid (ODPA) on ZnO nanowire sensors, recovery times for nonanal detection are significantly reduced without compromising sensitivity. Temperature-programmed measurements demonstrate a reduction in desorption temperature of carboxylates on ODPA-modified ZnO to below 150 °C, whereas carboxylates on bare ZnO remain above 300 °C, indicating a significant decrease in catalyst deactivation. Density functional theory calculations reveal that accumulated van der Waals interactions between alkyl chains and ZnO surfaces significantly contributed to adsorption molecular kinetics. IR spectroscopy using deuterated self-assembled monolayers (SAMs) reveals conformational changes of alkyl chains within the SAMs caused by aldehyde adsorption, supporting the suggested adsorption kinetics. A model is proposed based on the dynamic surface-covering by alkyl chains destabilizes catalytically oxidized carboxylic acids.