A coatable, lightweight nanocomposite sensor for in-situ acquisition of ultrasonic waves and its application to embeddable structural health monitoring

Lightweight and resilient, a nano-engineered sensor was developed, coatable to engineering structures via a screen printing approach, for in-situ acquisition of ultrasonic waves for implementing guided ultrasonic wave (GUW)-based structural health monitoring (SHM). Carbon black (CB)/polyvinylidene fluoride (PVDF)-based hybrid with various degrees of percolation were prepared, to fabricate the sensor. In an ultrasonic regime, GUW modulates the infrastructure of formed conductivity network of CB nanofillers with introduction of tunneling effect, and consequently changes the piezoresistivity manifested by the sensor. Morphological characterization, and static/dynamic electro-mechanical response tests were conducted to ascertain an optimal percolation threshold of the conductivity network. At the optimal threshold (∼ 6.5 wt%), the sensor exhibits high-fidelity, fast-response, and highsensitivity to GUWs up to 400 kHz. Addressing an innovative sensing philosophy of "quasidispersed sensing", the sensor presents a potential to strike a compromise between "sensing cost" and "sensing effectiveness", well accommodating the needs from GUW-based SHM.