Scientists have found that tiny vibrating devices known as nanomechanical resonators can lose energy even when they never physically touch anything else. This unexpected discovery could help engineers improve sensors, communication tools, and emerging quantum technologies. The study was conducted by researchers at the Swiss Federal Institute of Technology Lausanne (EPFL) and published in Nature Physics.
These nanomechanical resonators are incredibly small structures built onto computer chips. Despite their tiny size, they vibrate at astonishing speeds—ranging from thousands to billions of vibrations per second. Their high sensitivity makes them capable of detecting minuscule changes in mass, force, pressure, and temperature. They are commonly used in radio-frequency filters, timing devices, and advanced quantum physics experiments.
In many applications, these resonators need to be placed very close to other materials to measure their movements or interface with electronic or optical systems. While it was known that physical contact could impair their performance, this new research reveals that just being in close proximity can also cause issues. The team discovered that when a resonator vibrates near certain insulating materials, it can gradually lose energy without any contact. This energy loss reduces what scientists call the “quality factor,” a measure of how long the device can keep vibrating before slowing down.
The root of this hidden energy drain lies in tiny static electric charges embedded inside the resonator. As it vibrates, it creates a fluctuating electric field around it. If a nearby insulating material like silicon dioxide or silicon nitride has even minimal electrical losses, it absorbs some of this energy. Essentially, energy silently leaks from the resonator into the surrounding material, despite the two never touching. This phenomenon is related to noncontact friction, which has been observed in certain scientific instruments before.
To understand this effect better, the researchers developed a mathematical model predicting that slower vibrations would lose more energy than faster ones. They tested this by fabricating small silicon nitride resonators suspended roughly 500 nanometers (that’s half a micrometer) above an insulator. Their measurements confirmed the predictions: vibrations with lower frequencies experienced greater energy loss.
Further experiments involved more sophisticated resonators placed between tiny optical structures separated by gaps just a few hundred nanometers wide. As the gaps narrowed, device performance deteriorated significantly, with some quality factors dropping by up to tenfold.
This breakthrough offers valuable insight for designing future nanoscale devices. It highlights a practical limit to how closely components can be positioned without degrading performance. Interestingly, the researchers suggest that this effect could also serve as a new tool. By analyzing the hidden energy loss, scientists might be able to study electrical properties of extremely thin materials or develop novel ways to connect mechanical devices with electronic systems.
As nanotechnology advances, understanding these invisible energy losses becomes crucial. It will be fundamental for creating smaller, more sensitive, and more dependable devices for scientific research, medical applications, and the development of quantum technologies.
