Strain Sensors: Enhancing the Humidity Sensitivity of Ga₂O₃/SnO₂ Core/Shell Microribbon by Applying Mechanical Strain and Its Application as a Flexible Strain Sensor (Small 23/2012)

Single β-Ga2O3/amorphous SnO2 core/shell microribbon-based sensors are fabricated on page 3599 on a flexible substrate. In future life and health science fields, this sensor array can be used to detect the relative humidity of air at room temperature. Sensitivity increases linearly with strain, and can therefore be enhanced by the application of tensile strain (by bending the substrate). This strain-induced enhancement originates from the increase in the effective surface area where water molecules are adsorbed. This strain dependence of humidity sensitivity can be used to monitor the external strain. The strain sensing of the microribbon device under various amounts of mechanical loading show excellent reliability and reproducibility with a gauge factor of -41. These findings pave the way for new flexible strain and multifunctional sensors.