Resistance-type Humidity Sensor Using CNTs Sensing Material with Al2O3 Conformal Coating for Enhanced Sensitivity

摘要

This study presents a resistance-type humidity sensor using carbon nanotubes (CNTs) with Al2O3 coating. CNTs are typical materials for gas sensing and have the property resistance changing when absorbing moisture. Al2O3 is an excellent material for moisture absorption. Thus, this study uses the serpentine CNTs design integrated with Al2O3 conformal coating by Atom Layer Deposition (ALD) process to form a CNTs/Al2O3 composite for enhanced sensitivity of a humidity sensor. Features of this approach: (1) ALD Al2O3 to penetrate CNTs cluster and conformally coat on each CNTs surface; (2) High surface-to-volume ratio sensing structure offered by CNTs; (3) High moisture absorption capability offered by Al2O3 coating. Measurement results show that the sensitivity of the humidity sensors with 300°C annealed CNTs/Al2O3 composite is ~7-folds higher than that of bare-CNTs.