Liquid-level sensing by trapped-energy mode of backward-wave-type thickness vibration

Abstract

The authors have presented a new technique that employs a piezoelectric thickness vibrator operating in a trappedenergy mode for detecting a small-scale variation in liquid level. In this study, the feasibility of applying backward-wave-type energy trapping to liquid level sensing is investigated. It has been found that backward-wave-type energy trapping shows a sensing property slightly different from those obtained using conventional trapped-energy modes. Gradual variations in resonance characteristics with liquid level have been observed for backward-wave-type energy trapping when the liquid surface is in the surrounding electroded region