The next step was the fabrication of the sensor using GO
as the humidity sensing material, in which drop-casting was
adopted. In brief, a drop of GO dispersion (50 ml, 1.08 mg/ml,
dissolved in ethanol) was dropped onto the interdigitated
electrodes through a pipette, followed by drying under a
temperature 45 °C for 1 h. To more comprehensively examine
the sensing performance of the sensor, we characterized the
interdigital electrodes by scanning electron microscopy (SEM)
after being covered with GO films. As shown in Fig. 6,
the interdigitated electrode exhibits abundant wrinkles,
demonstrating complete coverage with the GO films.