At present, humidity sensors have promising prospects in disease monitoring, family life, environmental protection, and so on. Flexible humidity sensor is more and more popular because of its flexibility and portability. In our work, a flexible humidity sensor based on a tin disulfide (SnS2) nanoflower and a zinc stannate (Zn2SnO4) hollow sphere film was fabricated though layer-by-layer self-assembly technique. The humidity performance showed that the SnS2/Zn2SnO4 hybrid film sensor was ultrasensitive to humidity at room temperature. The test results demonstrated superior response, fast response/recovery behavior, and excellent repeatability. Moreover, compared to the single SnS2 and single Zn2SnO4 nanomaterials, the SnS2/Zn2SnO4 hybrid film sensor exhibited great improvement in humidity sensing. In addition, complex impedance spectroscopy was adopted to further explore the sensing mechanisms of the SnS2/Zn2SnO4 hybrid to various humidities. Human respiration, palm sweat, urine, and water droplets were delicately detected by the SnS2/Zn2SnO4 humidity sensor, indicating its great potential in multifarious application fields.
Keywords: SnS2 nanoflower; Zn2SnO4 hollow sphere; complex impedance plot; flexible humidity sensor; layer-by-layer self-assembly.