Measurement of Ultrasonic Phase Fluctuations Caused by a Plant Cell Using IDT System

Ultrasonic characteristics of a living plant cell are reported. A highprecision phase detection has been realized by a differential phase measurement system using focussed ultrasonic beams emitted from arched IDTs on a piezoelectric substrate. In the present system , a phase fluctuation of up to 0.1 deg. and the veloicity change larger than 2 mm/sec. can be detected. That plant cell, called Nitella, is well known to exhibit the electrical excitation and plasma streaming phenomena, and is often used for electrophysiological investigations. The phase measurements were made both at the steady states and the electrically excited state in Nitella, and the phase was found to be fluctuated. The fluctuation spectrum was examined by Fourier analysis.