New material enables accurate, mass production of air coupled ultrasonic sensors

A breakthrough in ultrasonic technology by CeramTec is enabling the consistent volume production of air-coupled ultrasonic transducers for level sensing, proximity detection, and flow monitoring of air and gas.

CeramTec's new air coupled matching layer uses a proprietary material, that is specifically developed to optimise loss-less transmission of ultrasonic signals through air.

This means that greater precision and complexity can be built into sensors, for accurate ultrasonic measurement across longer distances and a wider temperature range, minimising insertion loss in ultrasonic applications.

Crucially, CeramTec's manufacturing process achieves consistent matching of components. In ultrasonic flow measurement applications this usually removes the need to individually pair sensors to minimise undesirable acoustic interference, thereby opening up the technology for mass manufacture, as well as lowering the average zero flow offset between pairs of transducers and increasing the accuracy of these ultrasonic sensors.

The accuracy and sensitivity of the transducers also makes them suitable for applications requiring pinpoint precision of sensing, including the possibility of using three or more transducers in a triangulated configuration for three-dimensional ultrasonic mapping.

Potential applications include ultrasonic medical sensors, ultrasonic gas flow measurent and the ultrasonic automotive sensors, where the transducers' greater precision over bending mode transducers and unimorph configurations will improve performance cost-effectively.

"Air and other gasses are a challenging medium for the transmission of ultrasonics. There's always a great deal of acoustic turbulence that can subtly alter the soundwave, affecting the accuracy of data ," explains Charles Dowling of CeramTec.

"Historically, sensors have been paired manually to optimise performance, but that has limited the potential of the technology to smaller-scale applications because of the costs involved. We knew that if we could create ultrasonic sensors that would deliver improved performance, and can be manufactured consistently and cost-effectively, we could massively expand the possibilities of ultrasonic sensing for customers.

"Our new material technology opens up more advanced level sensing applications, especially within the industrial process and control sectors - as well as novel applications for proximity detection. For example, we see huge potential in new areas such as ultrasonic gesture recognition."

The matching layer has been developed specifically to minimise signal loss as the sound travels into the air. The ultrasonic matching layer is lightweight but extremely robust, being pressure-resistant, temperature stable and unaffected by harsh chemicals including toluene present in some gas based applications.

Combined with CeramTec's expertise in piezo ceramic components, the new range of sensors will exhibit sensitivites in excess of-40dB, these will be available in 400kHz and 200kHz as standard but also available to be customised.

The ultrasonic matchin layer is suitable to be used in a wide range of environments, and has been tested over a temperature range of -35C to 80C, with the option to customise to work at higher temperatures, if necessary.

With a small footprint of under 25mm in diameter and 30mm in depth, allied to a short ring down time, the new ultrasonic air-coupled transducers are versatile enough to measure distances to millimeter accuracy.

"This a substantial development in air-coupled ultrasonic sensors and we're very excited to bring this technology to customers. Until now, achieving this level of accuracy required the high costs associated with hand-made sensors, but we can mass produce sensors to give customers a competitive edge in their sensing capabilities."

For further information, please visit: https://www.ceramtec.co.uk/ceramic-materials/piezo-ceramics/

For more information, please contact :-

Simon Kinnear, Wyatt International
Tel +44 121 454 8181

Paul Turnbull, CeramTec UK
Tel +44 (0)1978 814101

December 2017

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