Researchers at ETH Zurich have unveiled a battery-free sensor that reacts to sound waves, marking a notable advance in passive sensing technology. The work appears in Advanced Functional Materials (AFM), a respected scientific journal known for publishing cutting edge materials research.
According to Johan Robertsson, a co author, the device operates entirely through mechanical means and does not rely on any external power source. It harvests energy from the vibration inherent in sound waves to drive its function.
The sensor is built around a silicon based metamaterial whose behavior arises from a distinctive structural design. By combining computer simulations with optimization algorithms, the team engineered a row of identical resonator plates linked by slender rods. When exposed to sound waves of a certain intensity, these plates behave like tightly wound springs, creating vibrations that translate into electrical signals which then stimulate the device’s electronic circuitry.
The researchers anticipate broad potential uses for this battery free, voice actuated system. It could be deployed to monitor seismic activity and the integrity of buildings, for example by listening for crack related noises in foundations. It could also detect gas line leaks by sensing characteristic hissing sounds and trigger alarms. In medical settings, the technology could support hearing implants and enable continuous measurement of intraocular pressure, among other possibilities.
A development timeline targets the launch of a solid state prototype by 2027. Future iterations are expected to distinguish up to twelve different words, including common commands like on, off, up and down. Compared with the current palm sized model, the team envisions versions that are as small as fingernails or even smaller, broadening potential form factors for integration into various devices.
Earlier work in the field includes efforts to create transparent, flexible implants designed to read brain activity, illustrating a broader trend toward durable, implantable sensing technologies.