Sound-powered sensors could make waves, reduce battery waste

A team at ETH Zurich, a public research university in Zurich, Switzerland, has developed a prototype mechanical sensor that leverages sound wave vibrations into energy, and does not require batteries.

Battery-powered sensors, like anything else that runs on batteries, require frequent replacement or recharging of the batteries, which can translate to downtime, added costs, and waste. In fact, a study from the European Union suggested in 2025 alone about 78 million batteries will end up in the trash. The issues of battery replacement and waste have been viewed as among the challenges limiting the potential growth of sensor-powered IoT networks. Power charging that leverages wireless signals has been observed as a possible alternative to battery-powered sensors in those cases.

But there may be other alternatives appropriate for certain use cases. ETH Zurich said a research team led by Marc Serra-​Garcia and ETH geophysics professor Johan Robertsson and working at Robertsson’s lab at the Switzerland Innovation Park Zurich in Dübendorf, was able to create a sensor that turns sound waves from certain spoken words or noises into electrical pulses that activate the sensor. 

The initial palm-sized, silicone-based device was built from “dozens of similarly structured plates that are connected to each other via tiny bars,” according to an ETH Zurich press release. “These connecting bars act like springs. The researchers used computer modeling and algorithms to develop the special design of these microstructured plates and work out how to attach them to each other. It is the springs that determine whether or not a particular sound source sets the sensor in motion.”

The researchers believe such sensors could have industrial applications, such as the monitoring transportation infrastructure, buildings, or decommissioned oil wells, where sound waves from earthquakes or other events could awaken the sensor and provide data. They also potentially could be used in medical devices like cochlear implants that currently work on external batteries that frequently need replacement.

Serra-​Garcia no longer works at ETH but at AMOLF, a public research institute in the Netherlands, where he and his team are refining their mechanical, sound-powered sensors. Their aim is to launch a solid prototype by 2027. “If we haven’t managed to attract anyone’s interest by then, we might found our own start-​up,” he stated.