Ultrasonication

Ultrasonication is the application of high-frequency mechanical vibrations, typically from 20 kHz to a few hundred kilohertz, to a sample. In liquids, the vibrations induce cavitation: the formation, growth, and collapse of microbubbles that generate localized heat, pressure, and shear. These effects can enhance chemical reactions, modify materials, and improve transport processes, making ultrasonication useful in laboratory and industrial settings.

Mechanistically, cavitation bubbles act as tiny reactors, producing shock waves and microjets at collapse. Frequency and power govern cavitation intensity: low-frequency, high-power ultrasound yields strong cavitation for cleaning and disruption; higher frequencies provide gentler effects for dispersion and delicate processing. Equipment ranges from ultrasonic baths to probe transducers, with cooling to control heat.

Applications include cleaning of instruments, emulsification and homogenization, dispersion of nanoparticles, extraction of natural products, degassing, and milling. In polymer and materials science, sonication aids degradation, crosslinking, and grafting, and enables synthesis of nanoparticles and composites. It also supports cell lysis in biology. Key parameters are frequency, power, duty cycle, solvent, temperature, and vessel geometry.

Safety considerations include heat buildup, potential damage to sensitive materials, and containment to limit exposure to reactive species. Reproducibility depends on reactor design and proper cooling. Users optimize parameters for the target material and ensure appropriate shielding and ventilation in industrial use.