Insulators Boost Energy Loss in Nanoresonators
EPFL researchers found that placing insulating materials near nanomechanical resonators can reduce their quality factor by as much as tenfold.
Updated on Nov. 3, 2026 in Physics
Researchers at EPFL reported on July 7, 2026, in Nature Physics that insulating materials placed a few hundred nanometers from nanomechanical resonators increase their energy loss. The mechanical quality factor can drop by as much as tenfold.
Why it matters
Nanomechanical resonators operate across frequencies from a few kilohertz to several gigahertz, so unexpected energy loss can limit their performance. Understanding the mechanism helps explain losses that were previously difficult to attribute.
The experiments used silicon nitride strings suspended about 500 nanometers above a dielectric layer, with the quality factor falling sharply as gaps narrowed to a few hundred nanometers near photonic crystal cavities. The extraction does not specify the full range of device geometries tested beyond these configurations.
The players
École Polytechnique Fédérale de Lausanne (EPFL)
A leading Swiss public research university where the discovery was made.
Tobias J. Kippenberg
The EPFL physicist whose research group carried out the study.
The details
Static electric charges trapped inside a mechanical resonator move with the structure as it vibrates, producing a changing electric field. That fluctuating field interacts with nearby insulating material such as silicon dioxide or silicon nitride, dissipating energy through its small electrical losses.
Timeline
July 7, 2026: Nature Physics publishes the study on non-contact friction in nanomechanical resonators.
The Big Picture
The effect is related to the noncontact friction earlier seen in atomic force microscopy, extending that phenomenon into nanomechanical resonators. The findings show that trapped charges can dominate energy loss in such devices, reshaping how researchers account for dissipation.
The results may enable characterization of electrical losses in thin films. Understanding these effects could help engineers preserve mechanical coherence in increasingly sensitive resonators.
The takeaway
Trapped charges near insulators can measurably drain energy from tiny vibrating devices, so designers of sensitive resonators should account for nearby dielectrics. The effect is strongest at lower frequencies, which is worth considering when specifying device operation.
Further reading
For related background, explore Physics coverage on Wisevoter.
Source note: This article includes information reported by SciTechDaily.
