- Michihiro Asakawa, from the University of Sussex
- Dr. Gianluca Memoli, from the University of Sussex
- Deepak R. Sahoo, from the University of Sussex
- Professor Sriram Subramanian, from the University of Sussex
- Dr. Mihai Caleap, from the University of Bristol
- Professor Bruce W. Drinkwater, from the University of Bristol
According to the abstract of the research paper, “Controlling acoustic fields is crucial in diverse applications such as loudspeaker design, ultrasound imaging and therapy or acoustic particle manipulation. The current approaches use fixed lenses or expensive phased arrays. Here, using a process of analogue-to-digital conversion and wavelet decomposition, we develop the notion of quantal meta-surfaces. The quanta here are small, pre-manufactured three-dimensional units – which we call metamaterial bricks – each encoding a specific phase delay.”
Using thermoplastics and a ProJet HD 3000 Plus 3D printer from 3D Systems, the collaborative research team manufactured the bricks themselves. Each brick’s shoulder bar filets helped to increase stability during manufacturing. Then, the researchers made a metamaterial layer out of many of the small bricks, each of which coils up space and slow down the sound. This means that any incoming sound waves can be be transformed, into any required sound field.
“Our metamaterial bricks can be 3D printed and then assembled together to form any sound field you can imagine,” said Dr. Memoli, from the Interact Lab at the University of Sussex. “We also showed how this can be achieved with only a small number of different bricks. You can think of a box of our metamaterial bricks as a do-it-yourself acoustics kit.”
The Interact Lab is part of the Creative Technology research group, and is a center for research excellence in human-computer interaction. The Lab focuses on creating novel interactive devices, and has specifically pioneered the design of systems which support mid-air displays and mid-air haptic feedback.
The metamaterial brick layers created by the research team have many potential applications, such as forming an audio hotspot by directing sound to a specific location. Small versions could potentially destroy tumors deep in a person’s body, by creating a patient-specific metamaterial layer and tuned to focus high intensity ultrasound waves where the tumor is located. With both of these examples, the brick layers of metamaterials can be made cheaply and quickly, and fitted to existing loudspeaker technology.“We want to create acoustic devices that manipulate sound with the same ease and flexibility with which LCDs and projectors do to light,” explained Professor Subramanian, Head of the Interact Lab. “Our research opens the door to new acoustic devices combining diffraction, scattering and refraction, and enables the future development of fully digital spatial sound modulators, which can be controlled in real time with minimal resources.”
“In the future I think there will be many exciting applications of this technology. We are now working on making the metamaterial layers dynamically reconfigurable,” explained Professor Drinkwater. “This will mean we can make cheap imaging systems which could be used either for medical diagnostics or crack detection.”
To learn more about this experiment and the acoustic metamaterial brick layers, check out this Interact Lab video:
Discuss in the Sound-Shaping Material forum at 3DPB.com.
[Source: University of Sussex]