A Novel Piezoelectric Resonator for Liquid Density and Viscosity Measurement

This paper presents a micromachined piezoelectric resonator based on microcantilever with out-of-plane vibration for liquid density and viscosity determination. The microcantilever mainly contained a T-beam and four piezoresistive beams, which has significantly different vibration modes in liquid compared with fundamental plate microcantilever. The focus was set on 2nd out-of-plane vibrational mode, excited in a novel wave-shaped operation mode in liquid media. Finite element simulations were performed to optimize the operation mode and analyze the resonance characteristics. A high quality factor of 223 was achieved in cyclohexane at 71 kHz, and the sensitivity was calculated by four organic liquids, and 34 Hz/$\left(\mathbf{k g} \cdot \mathbf{m}^{-3}\right)$ was achieved. The results indicated that the proposed novel resonator with wave-shaped mode reached high quality factor as well as high sensitivity in liquids measurements.