An Ultrasonic Aroma Diffuser is one that works on soft and silent ultrasonic waves to separate the essential oil and water into simpler molecules. After this, the diffuser sends the aroma into the air like a cool mist. The Ultrasonic Aroma Diffuser does not use any heat or fans or pump. The oil just rapidly evaporated through the air by tiny vibrations. You just have to dilute the essential oil with water.