Humidity-responsive multistate resistive switching device for non-contact sensory neuro-electronic applications

Integrated sensory-based synaptic systems offer a promising pathway for developing future neuro-electronic technologies that emulate the human brain. In this study, we present a humidity-sensitive multistate memristive device based on porous nickel pyrophosphate (Ni 2 P 2 O 7 ), designed for touch-free sensory neuro-electronic applications. The device exhibits distinct I – V characteristics under varying relative humidity (RH) conditions, with both the half-period time ( ) and hysteresis area showing significant modulation as a function of RH. These parameters serve as key indicators for evaluating humidity-responsive neuromorphic devices. Furthermore, the device demonstrates effective synaptic modulation when stimulated by a moisturized finger placed 1 mm away, enabling non-contact operation. Density functional theory (DFT) calculations were employed to analyze the intrinsic electronic properties of Ni 2 P 2 O 7 and to investigate the changes induced upon H 2 O adsorption. These findings suggest that the proposed Au/Ni 2 P 2 O 7 /fluorine-doped tin oxide (FTO)-based humidity-sensitive resistive memory device is a strong candidate for future non-contact sensory neuro-electronic systems designed to mimic brain-like functionality. • Porous Ni 2 P 2 O 7 memristor enables humidity-sensitive multistate switching. • Analog resistive switching achieved with tunable states under humidity. • Non-contact synaptic response demonstrated using moist finger proximity. • DFT shows H 2 O adsorption narrows bandgap and improves conductivity. • SVM and MLP classify proximity and humidity states with >97% accuracy.