PZT-based Multi-Mode Cantilever for Viscosity Sensing

We report a thin film Lead Zirconate Titanate (PZT) on Silicon-on-Insulator (SOI) based microcantilever for fluid dynamic viscosity (η
fluid
) sensing using optical and electrical characterization schemes. The viscosity of the medium is modulated by adding glycerol to deionized (DI) water. The measurements are carried over a viscosity range of 0.98-24.24 cP, which covers the operational range for biomedical applications. The fundamental cantilever mode yields a quality factor (Q) of 630 and 15 in air and DI water, respectively, whilst the second mode exhibits a Q of 840 and 30 in air and DI water, respectively. Sensor characterization using Laser Doppler Vibrometer (LDV) shows a power law relation between Q and η
fluid
$\left( {Q = a\eta _{fluid}^b} \right)$. A high relative responsivity of 0.38 and 0.41 with respect to η
fluid
is observed for the first and second flexural modes of the microcantilever, respectively. These results indicate the development of a good platform for on-chip viscosity measurements for biomedical and industrial applications.