Owing to investigation of stability of ultra-fine bubbles against external stimulus, we measured number concentration as a function of particle diameter of ultra-fine bubble after temperature change and phase change. Approximately same experimental results until temperature = 50 °C were obtained within the experimental errors. Moreover, number concentration decreased for magnitude of 1/10 after phase change (ice-state). Thus, high stability of ultra-fine bubble was obtained. Furthermore, strongly stability of ultra-fine bubble by a surfactant additive exhibited. For discussing deeply, additional experiment was conducted. Compared with the case of ultrasound, it was found that stability of ultra-fine bubbles against several types of external stimulus.
USHIDA et al. (Wed,) studied this question.