Flexible NO2 gas sensor with IGZO for enhanced mechanical and electrical stability

Flexible gas sensors for wearable electronics are often limited by performance degradation under mechanical deformation. This study presents a flexible nitrogen dioxide (NO 2 ) gas sensor based on a memristor heater (MH) structure using single-walled carbon nanotubes (SWCNTs) as the sensing layer. Hafnium dioxide (HfO 2 ) and indium gallium zinc oxide (IGZO) were compared as the active switching layer to evaluate their effects on sensing reliability under bending. The device operates through conductive filaments (CFs)-mediated resistive switching, enabling localized Joule heating at low voltage. Gas sensing was evaluated at 50 ppm NO 2 after bending to 0°, 30°, 60°, and 90°, and electrical stability was examined over up to 1000 bending cycles. The IGZO-based sensor maintained more stable gas response and electrical characteristics and exhibited much lower crack density after bending to 90°. These results suggest that limiting deformation-induced disruption of CF pathways may improve the operational reliability of flexible MH gas sensors.