Sensitive and wafer-scale olfactory sensory neurons.

Accurate and energy-efficient gas sensing remains a key challenge for next-generation artificial olfactory systems, particularly in applications such as unmanned aerial vehicles, wearable electronics, and humanoid robotic actuators. Inspired by the inherent selectivity and low-power information-processing mechanisms of biological olfactory neurons, we report an integrated olfactory sensory neuron (OSN) that simultaneously achieves high sensitivity and selectivity, signal stability, and neuromorphic spiking output. The device combines iodine-passivated colloidal quantum dots (CQDs) as molecular receptor layers with a wafer-level high-electron-mobility transistor (HEMT) transduction platform. The intrinsically low subthreshold swing and high on/off ratio of the HEMT enable efficient amplification of gas-induced charge modulation and allow the direct generation of spike-like signals. The artificial OSN achieves an ultralow detection limit of 0.5 ppb for NO₂ and successfully differentiates NO₂ from NO via principal component analysis (PCA). These results establish a scalable approach for neuromorphic olfactory modules, providing greater degrees of freedom for AI-driven olfaction and enabling compact, high-performance sensing in robotics, environmental monitoring, and healthcare applications.