An inkjet-printed, nanocomposites-inspired sensor network for acousto-ultrasonics-based structural health monitoring

In recognition of the bottlenecks of today’s ultrasonic sensors for health monitoring of aerospace structures, a flexible, lightweight, yet low-cost membrane-type sensor, made of carbon black (CB) and polyvinyl pyrrolidone (PVP), was developed. The sensor can be directly printed, coated or deposited onto a structure using inkjet printing facilities, to form a dense sensor network. Light and without using cable and wires, the printed sensor network significantly reduces the weight and volume penalty imposed to space structures even when the network is deployed in a large scale. It also minimizes the chance of exfoliation of sensors from the host structure under cyclic loads. The printed sensors show good performance in perceiving acousto-ultrasonic signals from static to up to 500 kHz, with a high signal-to-noise ratio, sensitivity and fidelity. The sensing mechanism of the developed sensor is the quantum tunneling effect in the CB nanoparticle-formed conductive network. This technique does not entail special printing facilities and the CB/PVP hybrid can be easily loaded in an inkjet cartridge for printing using Microsoft^® Office software. This fast sensor network prototyping method has vast potential to strike a balance between the sensing cost and sensing effectiveness in acousto-ultrasonic-based structural health monitoring.