We collaborate to integrate fundamental concepts from wave propagation, material science, signal processing, & electronics to build acoustic systems that solve global challenges in ecology, health, & the industry
About Our Work
The Metasonics lab specializes in acoustic materials, transducers, and systems for emerging domains such as the Internet of Things and Industry 4.0. We use sound and ultrasound for sensing, communication, and power transfer in challenging environments such as deep in the ocean, in the human body, and in nuclear waste containers. Our group designs and builds the circuits, acoustic devices, and signal processing software to generate acoustic and ultrasonic waves, control their propagation, and convert them back to useful electrical signals. We use 3D printing to design metamaterials that control acoustic wave propagation. Then use these metamaterials to build acoustic devices such as lenses, matching layers, and collimators. We also combine 3D printing and metamaterials to design novel piezoelectric (ultrasonic) transducers for novel applications.
A Metamaterial Lens for Focusing Sound Underwater
We designed and built the first 3D-printed acoustic lens for focusing acoustic waves underwater. Our solution used a desktop 3D printer to build the metamaterial lens using common polymers such as PLA or ABS. Since our lens can focus acoustic waves and make them more directional, we could use it to design underwater wireless chargers. Our lens improved the output power of an acoustic wireless charging system by a hundred times. In addition to underwater power transfer, our lenses can be designed to focus ultrasound for in-body imaging and treatment.
Battery-less Underwater Communications for Ocean IoT
Most of the ocean remains unexplored to date because it is hard to deploy sensors underwater and read their data efficiently. Wireless communications such as WiFi and 5G do not work underwater, and traditional acoustic communications that work underwater is power hungry. Acoustic backscatter is a communication technology that consumes 1 million time less power than existing solutions, but its communication range has been previously limited to a few meters. We developed the first theoretical model for acoustic backscatter communications and showed that it can work for kilometers of range. We have also shown that the range of acoustic backscatter can be increased by orders of magnitude using special arraying techniques
Ultrasonic Power Transfer Through-Metals
Ultrasonic waves are the only practical solution to transmit power and data through metallic enclosures. Using ultrasonic waves, we can wirelessly power-up sensors in nuclear waste containers or outside submarines and retrieve their measurements. We use piezoelectric transducers to convert electrical energy to ultrasonic waves that can efficiently travel through metals then convert it back to an electrical signal on the other side. In our work, we developed a detachable ultrasonic charger and showed that it can transmit more than 15 W of power. We also developed and experimentally verified the first complete model for ultrasonic power transmission through metals and showed that it can be done with 70% efficiency. Our technology will soon enable ruggedized mobile devices that do not need any physical ports for charging and communication.
Ultrasonic Transducers for the Internet-of-Things
Ultrasonic transducers can provide wireless charging and communication to IoT devices in extreme environments. For example, they can power up sensors and biomedical devices implanted in the human body. Avoiding the need for battery replacement and allowing for tiny implants. Such devices rely on ultrasonic transducers to both receive power and transmit their data, but modern transducers are commonly optimized for one task. We designed and built piezoelectric transducers that can simultaneously transmit power and data with high efficiency. To achieve this, we developed a novel frequency multiplexing technique for sending both data and power using a single transducer. Our work has shown that ultrasonic transducers can be designed to be both efficient and wideband for IoT applications.
Sound Energy Harvesting using Acoustic Metalenses
Modern IoT sensors and devices need very little power to operate but replacing their batteries is inconvenient and in many situations impossible if they are in hard to reach places. IoT devices can be charged using sound, however, the available power in everyday noises needs to be focused in a small area to be harvested efficiently. We developed a sound energy harvesting system consisting of a 3D-printed acoustic lens and a piezoelectric energy harvester. The lens focuses the sound energy at the harvester enabling a thousand times more power to be harvested compared to existing solutions. Our system could generate micro-Watts of power compared to nanoWatts in existing harvesters.
Detecting Defects in 3D-Printed Metals using Ultrasonic Waves
3D printing is developing at a rapid pace and manufacturers are increasingly relying on the technology to produce functional components. However, components made using 3D printing are prone to internal defects that can lead to premature failure. We are developing ultrasonic inspection solutions that can operate with emerging manufacturing technologies such as 3D printing. Our work has showed that ultrasonic phased arrays and guided waves can detect micro-scale defects in practical aerospace components. Moving forward, we seek to build low-cost automated ultrasonic systems for imaging functional 3D printed parts.
Acoustic Materials with Programmable Density
We designed active metamaterials whose acoustic properties can be electronically controlled from a graphical interface. The material consists of a repeating unit cell with active piezoelectric elements that can change its dynamic behavior. By applying a tailored voltage signal, we could program the material’s density to be fully transparent to sound, completely block it, or anywhere in between. The material can be used to design rooms with reconfigurable walls for immersive sound and virtual reality applications.