Measurement of a single microcapsule vibration in an acoustic standing wave field

Observation techniques for measuring the vibration of a single microcapsule in an acoustic standing wave field were discussed. First, optical simultaneous observation of a microcapsule vibration by two methods was investigated, using a high-speed video camera, which permits two-dimensional observation of the capsule vibration, and a laser Doppler vibrometer (LDV), which can observe small capsule vibration amplitudes at high-frequency. Capsule of tens of micrometer size was attached to a tape and oscillation behavior was observed at the antinode of an acoustic standing wave generated in an observational cell. Also, the biodegradable microcapsules are trapped at the antinode of the standing wave and the possibility of measuring vibration amplitude of microcapsule in the free field was suggested.