Fabrication of graphene/polyimide nanocomposite-based hair-like airflow sensor via direct inkjet printing and electrical breakdown

Herein we describe the fabrication and characterization of a novel flexible airflow sensor, consisting of a hair-like polyimide (PI) cantilever beam, a graphene/polyimide nanocomposite-based piezoresistor on the cantilever, and a double-deck PI film substrate. The airflow caused the deflection of the cantilever beam, and changed the resistance of the graphene/polyimide nanocomposite. The graphene/polyimide nanocomposite was fabricated by a direct inkjet printing process, while an electrical breakdown process was employed to endow the nanocomposite with excellent piezoresistivity, such that a gauge factor of 95 was achieved. The hair-like cantilever beam was created by a self-bending process driven by the embedded in-plane gradient stress of the bimorph materials, which consisted of pDADMAC/PI. The results of experiments indicated that the flow sensor had high resolution (∼0.5 m s −1 ), large detection range (0–20 m s −1 ), and good repeatability.