Two Teams Create First Full Sound Rainbows on Chips — SkimNews
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- Riyi Zheng at South China University of Technology and Yafeng Chen at Tongji University independently created the most complete elastic rainbows to date — Zheng on a silicon chip, Chen in an aluminium device — sorting phonon vibrations by frequency and localising each group at a distinct location.
- Both teams engineered microscopic patterns, such as tiny triangular pillars, that steer phonons by changing their speed and direction, mimicking how electromagnetic fields constrain electrons in thin materials.
- Chen's team imaged their rainbow by firing ultrasonic sound at the device and illuminating it with a laser; Chen said watching waves 'smoothly separate and localise at their exactly predicted locations was an incredible experience.'
- Zheng's team demonstrated the rainbow could route an incoming elastic wave through a single frequency 'patch,' analogous to isolating one colour from light.
- Sebastien Guenneau at Imperial College London said the electron-physics connection could open the door to studying quantum effects and Einstein's special-relativity phenomena in new material settings.
- Henning Schomerus at Lancaster University cautioned that practical devices remain distant, requiring smaller structures and higher trapped-vibration energy; Chen said his team is already pursuing 'ultra-compact on-chip acoustic devices.'
Why it matters: Two research teams have shown that phonons can be sorted and localised on-chip the way electrons are in a magnetic field — a proof of principle that compresses wave-steering physics onto compact devices. If the engineering challenges Schomerus flagged (smaller structures, higher trapped energy) are solved, it could enable vibration filters, ultrasonic routers, mechanical sensors, and energy harvesters built directly into chip-scale hardware.
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