[Back]

T. Manzaneque, V Ruiz-Díez, J. Hernando-Garcia, E Wistrela, M. Kucera, U. Schmid, J.L. Sànchez-Rojas:
"Density-viscosity Sensor Based on Piezoelectric MEMS Resonator and Oscillator Circuit";
Talk: IEEE Sensors 2014, Valencia, Spanien; 11-02-2014 - 11-05-2014; in: "IEEE Sensors 2014", IEEE, (2014), ISBN: 978-1-4799-0162-3; 241 - 244.

There are many examples of physical sensing in
liquid employing resonators, especially involving TSM quartz
crystals. Nevertheless, to determine density and viscosity
independently, out-of-plane vibration modes are required, what
typically results in low quality factors. Non-fundamental out-of-
plane vibration modes have not been deeply studied for this
application. Here we demonstrate the benefit of the 2nd-order
mode of a microplate. In addition, the device needs to be
electronically interfaced in order to measure its resonant
characteristics that are ultimately translated into density and
viscosity. For this, we have implemented an oscillator circuit with
discrete components, which supposes a novelty regarding
piezoelectric microstructures immersed in liquid. As a result, we
present for the first time a complete density-viscosity sensor
system based on a MEMS resonator embedded in low-cost
circuitry. The sensitivities involved are evaluated, along with the
resolutions for density and viscosity, below 4.09·10-6 g/ml and
2.07·10-3 mPa·s respectively.

There are many examples of physical sensing in
liquid employing resonators, especially involving TSM quartz
crystals. Nevertheless, to determine density and viscosity
independently, out-of-plane vibration modes are required, what
typically results in low quality factors. Non-fundamental out-of-
plane vibration modes have not been deeply studied for this
application. Here we demonstrate the benefit of the 2nd-order
mode of a microplate. In addition, the device needs to be
electronically interfaced in order to measure its resonant
characteristics that are ultimately translated into density and
viscosity. For this, we have implemented an oscillator circuit with
discrete components, which supposes a novelty regarding
piezoelectric microstructures immersed in liquid. As a result, we
present for the first time a complete density-viscosity sensor
system based on a MEMS resonator embedded in low-cost
circuitry. The sensitivities involved are evaluated, along with the
resolutions for density and viscosity, below 4.09·10-6 g/ml and
2.07·10-3 mPa·s respectively.

MEMS; piezoelectric; oscillator; liquid; density; viscosity

http://dx.doi.org/10.1109/ICSENS.2014.6984978

Project Head Ulrich Schmid:
Mikrosystemtechnik Projektkonto Schmid