Planar Metastructure-based Gas Sensors for High Stretchability and Stable NO2 Sensing

The paper presents a flexible and stretchable carbon nanotube (CNT) based gas sensor fabricated on a planar metastructure, kirigami substrate with anatase TiO
2
functionalization for improved NO
2
sensing performances with high stretchability. The developed kirigami-based sensor possesses a network of notches with high softness and stretchability, ensuring a stable sensor operation of up to 80% strain. Such a high strain range overcomes the current limitation of gas sensors, which generally utilize rather brittle and rigid sensing materials. The innovative claims include (1) the utilization of kirigami architecture to mitigate the uniaxial strain effect and (2) the enhancement of sensor performance regarding the sensitivity and recovery time owing to TiO
2
functionalization. Mechanical properties of the kirigami structure can be analyzed via stress-strain relation, and the sensing material properties are characterized using Fourier-transform infrared spectroscopy (FT-IR) and Raman spectroscopy. The suggested kirigami-based gas sensors could be applied to wearable and stretchable gas sensing applications.