Hong Kong researchers develop ‘sprayable’ sensor technology

Researchers from the Hong Kong Polytechnic University (PolyU) have developed sprayable sensor network technology to assist in real-time structural health monitoring.

The nanocomposites-inspired sensors can be sprayed directly on a flat or curved engineering structural surface such as train tracks and aeroplane components.

The sprayed sensors are then networked to render real-time information on the health status of the structure under monitoring.

The technology encompasses a sensor network with the nanocomposite sensors and an ultrasound actuator, to actively detect the health condition of the structure to which they are fixed, quickly and accuratele show if there is any damage in the structure.

When the ultrasound actuator emits guided ultrasonic waves (GUWs), the sensors will receive and measure the waves. If damage, such as a crack is present in the structure, propagation of GUWs will be interfered by the damage, leading to unique wave scattering phenomena, to be captured by the sensor network.

Based on wave scattering, the damage can be characterised quantitatively and accurately via an all-in-one system that was developed by the team.

According to a PolyU, by fabricating the sensors through spraying, the installation process is much faster and more efficient compared with conventional means. It also enhances the flexibility of the product to adapt to various types of surface.

“This nanocomposite sensor has blazed a trail for implementing in-situ sensing for vibration, or ultrasonic wave-based structural health monitoring, by striking a balance between ‘sensing cost’, i.e. the cost of sensors, and ‘sensing effectiveness’, the quantity of data acquired by the sensors,” said Professor Su Zhongqing who, along with Professor Zhou Limin, led the research team from PolyU’s Department of Mechanical Engineering that developed the nanocomposite sensors.

“Due to its light weight, the novel nanocomposite sensors can be applied to moving structures like trains and aeroplanes. That will help to pave the way for real-time monitoring of these structures in future, enhancing safety of the engineering assets and retrofit the traditional system maintenance philosophy,” she said.

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