posted on 2020-12-15, 19:40authored byYonggang Jiang, Qipei He, Jun Cai, Dawei Shen, Xiaohe Hu, Deyuan Zhang
Carbon-based piezoresistive nanomaterials
are widely used for the fabrication of flexible sensors. Although
our previous work demonstrated that an electrical breakdown (EBD)
process can endow a graphene/polyimide (G/PI) composite with piezoresistivity,
the formation of EBD-induced electrical traces with high consistency
in bulk nanocomposites remains a technical challenge. With the aim
of developing highly sensitive flexible strain sensors using a batch
fabrication process, we introduce herein a microscale EBD (μEBD)
method to form localized piezoresistors with diverse shapes in a G/PI
thin film. The results of scanning electron microscopy, Raman spectroscopy,
and electromechanical tests indicate that high piezoresistivity is
derived from the high porosity of the carbonized conductive traces
generated by the μEBD process. The gauge factor of the μEBD-treated
G/PI strain sensor is over 20 times greater than that of the as-prepared
G/PI film, and the sensitivities of the strain sensors can be tuned
by varying the applied current in the μEBD process. We also
demonstrate the potential applications of μEBD-treated G/PI
strain sensors in the fields of finger gesture detection, sound pressure
measurement, and airflow sensing.