Viscosity Measurement Method Using Central-mode Piezoelectric Resonator Embedded in Bottom of Plastic Vessel

Abstract

In this paper, a viscometor suitable for food-processing process is proposed. This viscometer can measure a small amount of liquid, be easy to care, and embed in pipe. This viscometer has disk-shaped piezoelectric resonator embedded in bottom or wall of vessel and pipe. Viscosity is obtained by estimating equivalent circuit parameters of piezoelectric resonator at resonance. To measure viscosity in the case of gluing the circumference of the resonator to the vessel, center of the piezoelectric resonator is vibrated by proposed electrode arrangement. To verify effectiveness of proposed viscometer, the viscometer was made and relationship between resistance R_s obtained by equivalent circuit of piezoelectric resonator and viscosity η of standard liquid of calibrating viscometor was confi rmed. In this confi rming, standard liquid of calibrating viscometor as measurement sample was 10 mL. As a result, radial-mode vibration did not give one-to-one correspondence η and R_s. However, central-mode vibration gave one-to-one correspondence η and R_s, and η was proportional to R_s² in the range of 9.1 - 478 (mPa・s). Therefore, proposed viscometor can be embedded bottom of vessel, and measure a small amount of sample. Thus, it was shown that proposed viscometor is suitable for food-processing process.