Improvement of capacitive humidity sensors using tris(8-hydroxyquinoline) gallium (Gaq3) nanofibers as a dielectric layer

Abstract

In this research work, we improved the sensing response of the organic-based co-planar humidity sensors using tris(8-hydroxyquinoline) gallium (Gaq3) nanofibers as a dielectric material. The humidity sensor was fabricated by a drop-casting solution in the gap between pre-deposited silver (Ag) electrodes to form Ag/Gaq3/Ag-based capacitive-type humidity sensor. The morphology of the Gaq3 films has been investigated by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). At room temperature, the capacitive response of the sensor is evaluated in the range of 0 to 95%RH at 120 Hz & 1 kHz. Notably, at 1 kHz frequency, the sensor shows fast response, good sensitivity, and low hysteresis. The response & recovery times were found to be 6 s each, which are way smaller than those reported in the literature. Such features demonstrate that Gaq3 nanofibers are an up-and-coming candidate for making very sensitive and fast humidity sensors.