A flexible electrostatic nanogenerator and self-powered capacitive sensor based on electrospun polystyrene mats and graphene oxide films.

Electrostatic nanogenerators or capacitive sensors that leverage electrostatic induction for power generation or sensing, has attracted significant interests due to their simple structure, ease of fabrication, and high device stability. However, in order for such devices to work, an additional power source or a post-charging process is necessary to activate the electrostatic effect. In this work, an electrostatic nanogenerator is fabricated using electrospun polystyrene (PS) mats and dip-coated graphene oxide (GO) films as the self-charged components. The electret performances of the PS mats and GO films are characterized via the electrostatic force microscopy phase shift and surface potential measurements. With a multilayer device structure that consists of top electrodes/GO films/spacer/electrospun PS mats/bottom electrodes, the resultant device acts as an electrostatic generator that operates in the noncontact mode. The nanogenerator can output a peak voltage of ca. 6.41 V and a peak current of ca. 6.57 nA at a rate of 1 Hz of mechanical compression, and with no attenuation of electrical outputs even after 50 000 cycles over a 13 h period. Furthermore, this as-prepared device is also capable of serving as a self-powered capacitive sensor for detection of tiny mechanical impacts and measurement of human finger bending. This results of this work provides a new avenue to easily fabricate electrostatic nanogenerators with high durability and self-powered capacitive sensors for the detection of small impacts.