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New Nanocomposite Sensors Can Form Sensor Networks
[China Instrument Network Instrument Development] Recently, the Hong Kong Polytechnic University's research team has developed a new nanocomposite sensor that can be directly applied to flat or curved engineering structures such as train rails and aircraft structures.
The sprayed out sensor can further form a sensor network, providing real-time and rich structural health information for the monitored structure.
It is reported that nanocomposite sensors are researched and developed by Professor Su Zhongqing, Prof. Zhou Limin, and the team headed by them in the Department of Mechanical Engineering of PolyU. They are made using innovative spraying technology, making the sensor installation process faster and more efficient than traditional methods. This new technology also makes this sensor suitable for a variety of engineering structure surfaces, increasing its flexibility.
Professor Su said that the new nanocomposite sensor can take into account both the cost of the sensor and the amount of data captured by the sensor network, opening up new ideas for in situ vibration sensing and ultrasound-based structural health monitoring technology. .
New technology reduces costs and increases sensitivity
The nanocomposite sensor is made of a mixture of carbon black, two-dimensional graphene, conductive nano-particles and polyvinylidene fluoride, and can be easily and flexibly made into different sizes according to the needs of various engineering applications.
The new nanocomposite sensor can sensitively detect structural changes due to optimization of the nanostructure of the mixture, and it can recognize the feedback of different nanocomposites on different piezoresistance.
In this new technology, each sensor is connected to the network through wires printed on the structure. Through the analysis and comparison of electrical signals converted from resistivity, defects in the structure can be found, and the signals are converted into three-dimensional images. .
Light weight and low cost
It is understood that this type of sensor is extremely light-weight and inexpensive to manufacture, and it can be used in large numbers to detect problems hidden inside the structure, helping to create a new era of ultrasound-based structural health monitoring.
It consists of a sensor network consisting of multiple nanocomposite sensors and an ultrasonic transducer that proactively detects the health of the structure in which the sensor network is installed, and quickly and accurately shows whether the structure is damaged.
The sensor will receive and measure the ultrasonic guided waves emitted by the ultrasonic transducer. If the structure is damaged, for example, cracks occur, the propagation of the ultrasonic guided wave will be disturbed by the damaged place, so that the special wave scattering phenomenon occurs and the sensor network is recording. The integrated system developed by the team can accurately detect and quantify structural damage based on the scattering of ultrasonic guided waves.
It is reported that the traditional ultrasonic sensor is made of piezoelectric materials, the cost is more than ten dollars, weighs several grams; and this new generation of nano-composite sensors costs only 0.5 US dollars, weighing 0.04 grams.
Therefore, a structure can use more sensors at the same time to get richer information for analysis without giving significant weight to the structure.
Better flexibility, suitable for curved surface
In addition, this nanocomposite sensor has excellent flexibility and is suitable for curved structural surfaces. It can be widely applied to various engineering structures. Even on the surface of moving structures, it can also be installed by spraying, and the structure can be transferred in real time. Health information.
Su Zhongqing said that he has contacted the research institutes in the Mainland and will use new technologies for aviation structures in the future. News chart
More responsive
This nanocomposite sensor can measure ultra-small amplitude ultrasonic signals from rest to 900 kHz. This technology collects scattered waves in an ultrasound system to detect microscopic one to two millimeter cracks in most engineering materials at a frequency 400 times higher than the response frequency of existing nanocomposite sensors (according to current reports in international journals). Multiple times.
Although the ultrasonic range that can be measured by conventional ultrasonic sensors is wider than the response frequency of this nanocomposite sensor, the traditional sensors have high weight and cost and are difficult to use in large quantities to form a large sensor network. Therefore, they can only bring limited data. data. In practical applications of many projects, especially for aerospace structures, there are great restrictions on their use.
(Original title: Hong Kong Polytechnic University creates a low-cost, high-sensitivity paintable sensor)