A super-substance that shapes, bends and focuses sound waves that pass through it has been discovered by researchers. The creation pushes the boundaries of metamaterials – a novel group of finely-engineered surfaces that perform the nature defying tasks.
Such substances have already revealed remarkable results with light manipulation, enabling researchers to create a real-life version of Harry Potter’s invisibility cloak, for instance. But a scientific group from the Universities of Sussex and Bristol have now revealed that they also work with sound waves, which could transform medical imaging and personal audio.
Finely shaped sound fields are employed in medical imaging and therapy as well as in an extensive assortment of consumer products like ultrasonic haptics and audio spotlights. The study is also introduced in Nature Communications reveal a simple and cost-effective method of creating these shaped sound waves using acoustic metamaterials.The collaborative research group assembled a metamaterial layer out of lots of small bricks that each coil up space. The space coiling bricks act to slow down the sound meaning that incoming sound waves can be altered into any required sound field.The novel metamaterial layers could be employed in numerous applications. Large versions could be used to direct or focus sound to a specific location and form an audio hotspot. Much smaller versions could be employed to direct or focus sound to a specific location and form an audio hotspot. Much smaller versions could be employed to focus high intensity ultrasound to destroy tumours deep within the body. Here, a metamaterial layer could be tailor-made to fit the body of a patient and tuned to focus the ultrasound waves where they are required most.
In both situations the layer could be fitted to existing loudspeaker technology and be prepared cheaply and rapidly. Dr. Gainluca Memoli, from the Interact Lab at the University of Sussex who headed the study, says “Our metamaterial bricks can be 3D printed and then organized together to form any sound field you can imagine. We also revealed how this can be accomplished with only a small number of distinct bricks. You can consider of a box of our metamaterial bricks as a do-it-yourself acoustics kit.
Lecturer Srriram Subramanium, Head of the Interact Lab at the University of Sussex stated, “We want to prepare acoustic devices that manipulate sound with the same ease and flexibility with the LCDs and projectors to do light. Our study opens the door to novel acoustic devices linking diffraction, refraction and scattering, and allows the future development of fully digital spatial sound modulators, which can be regulated in real time with minimal resources.”
Bruce Drinkwater, Lecturer of Ultrasonics at the University of Bristol, explained, “In the future I consider there will be numerous exciting applications of this technology. We are now working on making the metamaterial layers dynamically reconfigurable. This will mean we can make cheap imaging systems, which could be employed either for medical diagnostics or crack detection.”
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