Máy rửa siêu âm mini: nguyên lý, cách dùng và đồ không nên rửa

Glasses, rings, watch bands and dentures are full of tiny crevices that cloths and brushes struggle to reach. A mini ultrasonic cleaner gets into these spots using countless microscopic bubbles formed in water. This guide explains how it works, what the kHz figure means, what you should and shouldn't put in it, how to use it, and what to know about UVC lamps.

How does a mini ultrasonic cleaner work?

• A transducer under the tank vibrates at ultrasonic frequencies, above the range of human hearing (about 20 kHz).
• The sound waves create rapidly alternating zones of high and low pressure in the water. In the low-pressure phase, tiny bubbles form and grow; when compressed, they collapse violently. This is called cavitation.
• According to a review by Yusof et al. (2016, Ultrasonics Sonochemistry), the oscillation and collapse of these bubbles generate shear forces, microjets, microstreaming and shockwaves. These forces lift dirt and grease off surfaces and out of crevices. PubMed
• The method dates from the mid-20th century and is now widely used for surface cleaning (Mason, 2016).

What does the kHz frequency change?

• Brotchie et al. (2009, Physical Review Letters) measured bubble sizes at different powers and frequencies: mean bubble size increased with power and decreased as frequency rose. PubMed
• The Yusof review notes that strong physical forces are produced at low ultrasonic frequencies, such as 20 kHz.

In simple terms: lower frequencies give larger bubbles and stronger forces, suited to stubborn dirt on robust items. Higher frequencies give smaller bubbles and gentler action, which suits small, delicate household items. Results also depend on power, cleaning time, water temperature and solution, not just the kHz number.

What can a mini ultrasonic cleaner clean?

• Glasses: frames and lenses with intact, unscratched coatings.
• Gold, silver and platinum jewelry: pieces without stones, or with durable stones in secure settings.
• Metal watch bands: remove the band from the watch head first, unless the manufacturer says the whole watch can be immersed.
• Dentures, clear aligners and retainers: a trial of 80 denture wearers found that, on top of brushing, an ultrasonic device reduced biofilm about as well as effervescent cleaning tablets (Cruz et al., 2011). See also our guide on how to clean dentures.
• Small personal items: electric toothbrush heads, water flosser tips, razor blades.

What should not go in an ultrasonic cleaner?

The Gemological Institute of America (GIA) lists these cases to avoid:

• Pearls and organic materials: coral, tortoise shell, ivory, shell cameos, jet and amber. GIA's pearl care page is explicit: “Pearls should never be cleaned in an ultrasonic or steam cleaner.”
• Stones impregnated or coated with oil, plastic or wax: such as emerald, lapis lazuli, malachite and opal. GIA notes estimates that 90% or more of emeralds are fracture-filled, and vibration can weaken already fractured stones. GIA
• Fracture-filled stones, including diamonds, and dyed stones (GIA).
• Heat-treated stones, star rubies and star sapphires.
• Stones sensitive to heat or temperature change, treated or not: turquoise, opal, moonstone, tanzanite, topaz, zircon, kunzite, fluorite.
• Stones in loose settings, as vibration can shake them out.

If you're not sure what you have, GIA advises skipping the ultrasonic and using warm, soapy water. As a precaution, also keep out items with glued parts, non-water-resistant watches and electronics; for lenses with scratched or peeling coatings, or expensive lenses, ask your optician first.

How to use a mini ultrasonic cleaner correctly

1. Fill with clean, lukewarm water up to the mark in the instructions and add a few drops of mild dish soap.
2. Never run the machine with an empty tank.
3. Make sure items are fully submerged and not piled on top of each other.
4. Choose a cycle: start with 3 minutes for light dirt, 5–10 minutes for heavier dirt.
5. Rinse items in clean water and dry them with a soft cloth.
6. Empty the dirty water and wipe the tank dry after each use.

UVC lamps in ultrasonic cleaners: what to expect

• According to the CDC, UV radiation has its maximum bactericidal effect at 240–280 nm. Its effectiveness is influenced by organic matter, wavelength, temperature, type of microorganism and UV intensity, which drops with distance.
• A UVC lamp in a household device is a supplementary surface disinfection step, not medical sterilisation.
• Safety: the FDA warns that high-output UVC devices can injure skin and eyes after just a few seconds. Don't open the lid to look at the lamp while it is on, and don't let children run the machine on their own.

Mini ultrasonic cleaners from Inmax

• U27 ultrasonic cleaner: 48 kHz with a 270–280 nm UVC lamp, 200 ml capacity, countdown display on top, 22 W. Modes: 3, 5 and 10 minutes of ultrasonic + UV, and 5 minutes of UV only.
• U13 ultrasonic cleaner: the same 48 kHz in a 108 mm cylindrical body with a silver-plated lid and front indicator lights for 3/5/10 minutes and UV; smaller and lighter than the U27 (298 g), 20 W.

The U27's UVC wavelength falls within the CDC range above, but it remains a supporting step after washing. Browse all ultrasonic cleaners or compare models. Optical shops and jewelers interested in stocking them can check our dealer policy (discounts from 10 units) or contact Inmax.

Frequently asked questions

Can an ultrasonic cleaner damage jewelry?

The risks GIA highlights mainly involve treated gemstones, organic materials and loosely set stones. Check the settings and the list above before cleaning.

What liquid should I use in a mini ultrasonic cleaner?

Clean, lukewarm water with a few drops of mild dish soap. Do not use flammable solvents such as petrol or concentrated alcohol.

Can the UVC lamp replace washing?

No. The CDC notes that organic matter reduces UV effectiveness, so clean items first.

This article is for general information. For valuable jewelry or gemstones whose treatment history you don't know, ask a jeweler before using an ultrasonic cleaner.