How Does an Ultrasonic Humidifier Work?

In one of our previous articles, we talked about the ultrasonic humidifier, what is it, and why you should or should not get it, considering its strong and weak sides.

In this article, we are diving into the topic a bit deeper, as we are going to answer the question “how does an ultrasonic humidifier work?

To give you a brief introduction, humidifiers are used to increase the air humidity levels in your home and eliminate the dry air that is usually considered unhealthy, as it makes you more prone to colds and flu. A humidifier should help relieve a stuffy nose and get rid of any mucous you may have.

During wintertime, if the humidity levels are slightly enhanced, to some 40-50%, it feels warmer inside, which is an additional reason why some people like to use a humidifier. In the long run, it can help you save money on your utility bills.

There are several types of humidifiers including ultrasonic, warm-mist, vaporizer, impeller, and evaporative, each working slightly differently than the other, and each having its own advantages and disadvantages.

Now, we focus on the ultrasonic humidifier and the way it works to help you create an optimal atmosphere in your indoor space.

What Does an Ultrasonic Humidifier Do?

An ultrasonic humidifier produces a mist that ends up in the indoor air that you breathe. The molecules of water released into the air are less than one micron in diameter, making them exceptionally small and the air absorbs them almost immediately.

Ultrasonic humidifiers operate very quietly and don’t need a filter, which means less work for you when it comes to maintaining the unit.

Unlike some humidifiers that actually boil water, the water in the ultrasonic unit may contain some impurities that are usually present in hard water. For example, tap water may result in some white dust settling around your home, however, you can solve this by using distilled water.

Another option is to choose the humidifier demineralization filter and prevent the creation of white dust, while still pouring tap water into the humidifier.

The tank of the ultrasonic humidifier needs to be clean in order to achieve desired results. If you don’t clean it, you risk growing certain types of pathogens inside that will later be expelled into the air. This means that although you don’t have to bother about a filter, you still need to clean the tank of your humidifier.

How Does an Ultrasonic Humidifier Work?

The main mechanism of how the ultrasonic humidifier works (compared to its counterparts) is that it releases droplets into the air. Thanks to a metal diaphragm that sends high-frequency vibrations that propel the moisture into the air, the tiny microscopic water droplets are being released (and quickly absorbed) into the air.

The vibrations of an ultrasonic humidifier are usually outside of the range of 20-20,000 Hz, which is the range of human hearing, meaning that these humidifiers produce almost no sound at all, and you can comfortably use them during the night, without fearing that they will keep you awake with their unpleasant noises. Other types of humidifiers can produce loud noise for example as the water is boiling inside them.

Another reason why this humidifier is so silent is that it doesn’t use any kind of fan. The high-frequency vibrations themselves are enough to spread the water droplets into the air.

Every ultrasonic humidifier has a piezoelectric ceramic disc. This disc has two nickel electrodes to deliver power. The piezoelectric disc then oscillates at an ultrasonic frequency, thus the name, and thus the silence. The oscillation frequency then rises and the water follows this frequency as it oscillates with the plate, but it fails to match that frequency due to its weight and inertia, which then causes water hammers.

This process further makes room for the process of cavitation to happen, as due to the low pressure created between the water wave and the disc, the cavity begins to form. The cavity is either in the form of a void or is filled with air as the air dissolves in water, and as the low pressure is being formed, it moves into the cavity.

The cavity then implodes and this creates some energy. The disc that is vibrating is also making capillary waves on the water surface. The wave oscillations will keep on going up and down thanks to the tension of the surface and the gravity. When the cavity implodes, there is a new crossed capillary wave that appears on the surface at the crest of the wave, as a result of this process. The water droplets that are fuelled with energy are then able to break off the tension on the surface. Once the droplets reach the surface and spread into the air they are being spread into the air and absorbed by the air. They leave the humidifying unit in the form of a mist. The higher the frequency of the disc oscillation, the smaller the aerosols.

Why Are Ultrasonic Humidifiers a Good Option for Your Home?

Primarily, ultrasonic humidifiers are very effective in creating water mist. The level of their effectiveness is so high, that you may be under a risk of over humidifying the space if you’re not careful. Look for a unit that has a humidistat to help you control the humidity levels in your room.

Then, as mentioned above, the ultrasonic units are usually very quiet in their performance, as they use fast vibrations instead of a fan. The ultrasonic humidifiers are also safe for kids, therefore, you can use them in a children’s room or even in a nursery.

The energy expenditures of this unit are very low compared to other types of humidifiers, especially those that boil water.

Potentials Issues with the Ultrasonic Humidifiers

Potential drawbacks of this type of unit are that they may produce some dust if you use tap water and if you don’t clean them often. Furthermore, damp areas are possible if you are using the unit in a cold or an already moist room, as some droplets won’t get a chance to evaporate and will form puddles. Finally, despite the fact that we can’t hear this unit when it’s working, dogs can. If you have a dog, you may notice some signs of discomfort in them once you set the unit into action.

Silver Clean Technology

Certain ultrasonic humidifiers use a special type of technology called Silver Clean Technology that helps prevent the creation of mold on the water tank surface. The brands known to use this technology are Guardian Technologies, Pure Guardian, and probably many others.

This technology is important as they help you prevent the formation of pathogens inside the unit’s reservoir, that would otherwise be expelled into the air.


If you’re looking for a unit that will add a few degrees of temperature on cold days to your indoor space as well as improve the humidity status of your home, perhaps the ultrasonic humidifier is the right choice for you. These units have very efficient operating mechanisms, they are quiet, and energy-saving.

Make sure to purchase a unit that has a humidistat to prevent potential over humidification.