Eyewear Care & Ultrasonic Cleaning
What Is an Ultrasonic Cleaner and How Does Cavitation Work?
An ultrasonic cleaner uses high-frequency sound waves (typically 40,000–48,000 Hz) to generate millions of microscopically small bubbles in a liquid. As these bubbles implode, they create a mechanical cleaning effect – with zero friction on the surface. This effect is called cavitation.
The physical principle: cavitation
A transducer at the bottom of the tank generates vibrations in the ultrasonic range – for consumer devices, typically between 40,000 and 48,000 Hz, well above the human hearing limit of around 20,000 Hz. These vibrations alternately create low- and high-pressure zones in the liquid.
Tiny vacuum bubbles form in the low-pressure zones. As soon as they enter a high-pressure zone, they implode instantly. This implosion releases locally enormous, but extremely small-scale, energy – enough to dislodge dirt particles from a surface, but too fine to damage sensitive materials like lens coatings.
Why this works so well specifically for glasses
The bubbles form throughout the entire volume of liquid – including in hinges, nose pads and the finest grooves that a cloth or a finger would never reach. Since nothing rubs against the lens, there's also no mechanical scratch risk, unlike wiping with clothing or paper (see Why you should never put washing-up liquid in an ultrasonic cleaner for a related point).
Where does the technology originally come from?
Ultrasonic cleaning has been used for decades in industry (precision components), dental practices (instrument cleaning) and the jewellery trade. Consumer devices for glasses and jewellery are essentially the same technology, just miniaturised and tuned to lower power for sensitive everyday items.
The timer in action
A visible countdown makes the invisible cavitation process tangible: the built-in timer counts down while, behind the scenes, millions of bubbles implode.
Frequently asked questions
Is ultrasonic cleaning suitable for all materials?+
No. Sensitive, porous or glued materials (e.g. pearls, opals, some gemstone settings) shouldn't go in an ultrasonic cleaner – more on that in our FAQ.
How loud is the process?+
Since the actual sound wave itself is outside the range of human hearing, all you hear is the device's own operating noise – for NURO, under 45 dB, quieter than a fridge.
Author: Moritz Weinert, Gründer NURO Labs · Last updated on 10 September 2026