01 · Ultra-small size
Invisible, under 1 µm
UFB are less than 1 µm (1000 nm) in diameter — about 1/1000 the width of a human hair. They scatter almost no light, so the water stays clear even when they are dispersed in it.
Ultra-fine bubbles (UFB) are extremely small bubbles less than 1 µm (micrometer) in diameter. They have physical properties completely different from ordinary bubbles, and these properties underpin a wide range of effects — cleaning, water quality improvement, higher dissolved gas, and more. Below are the six representative UFB properties commonly described in academic literature.
UFB are less than 1 µm (1000 nm) in diameter — about 1/1000 the width of a human hair. They scatter almost no light, so the water stays clear even when they are dispersed in it.
Ordinary bubbles rise quickly and burst, but UFB have almost no buoyancy, so they stay dispersed and stable in water for weeks to months.
Splitting the same amount of gas into tiny bubbles increases the gas–liquid contact area by hundreds to thousands of times. Gases like oxygen dissolve into water far more readily, raising dissolved-gas efficiency.
UFB surfaces carry a negative charge (zeta potential of about −40 mV). The bubbles repel one another so they stay stable without coalescing, while attracting positively charged contaminants and particles to aid separation and adsorption.
Thanks to their ultra-small size and negative charge, UFB penetrate and adsorb onto contaminants in fine gaps and textures that ordinary water struggles to reach, lifting them away. This enables physical cleaning with less detergent.
When a bubble shrinks and collapses, a locally high energy is released, which can generate reactive oxygen species such as ·OH. This is the principle behind their oxidizing, decomposing, and sterilizing action.
※ The properties and values above (e.g., zeta potential ≈ −40 mV, diameter < 1 µm) are explanations based on general academic literature on ultra-fine bubbles. Actual effects and measured values may vary with application conditions such as gas type, water quality, and generation method.
A general-technology overview of bubble classification, generation methods, measurement, and application principles.
Milli-bubble
Ordinary visible bubbles. Their large buoyancy makes them rise quickly to the surface and burst.
Micro-bubble
Rise slowly while shrinking and dissolving. They appear milky white and are used for cleaning and dissolved-oxygen enhancement.
Ultra-fine bubble (UFB)
Almost no buoyancy, so they stay suspended in water for a long time. They scatter little light (appearing clear) and repel one another via their negative charge, remaining stable.
Raises dissolved oxygen in irrigation water, supporting root respiration and nutrient uptake to improve the growth environment.
Replenishes dissolved oxygen in drinking and rearing water and helps manage water quality and odor.
Penetrates fine gaps to physically lift contaminants away, enabling cleaning with less detergent.
Supports water-quality improvement in reservoirs and purification processes through flotation separation and oxygen supply.
※ This summarizes general technical and academic literature on ultra-fine bubbles. Actual effects and values may vary with gas type, water quality, generation method, and application conditions.
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