Viscosity sensor utilizing a piezoelectric thickness shear sandwich resonator

Area of Science:

• Materials Science
• Physical Chemistry
• Sensor Technology

Background:

• Accurate measurement of liquid properties like density-viscosity product is crucial in various scientific and industrial applications.
• Traditional methods often face challenges with sample volume, accuracy, and interference from compressional waves.
• Existing quartz crystal sensor designs can be susceptible to disturbing resonances, affecting measurement reliability.

Purpose of the Study:

• To develop and describe a novel quartz crystal sensor for precise measurement of the density-viscosity product of Newtonian liquids.
• To overcome limitations of single-plate sensor arrangements by suppressing unwanted resonances.
• To enable accurate measurements using a small sample volume.

Main Methods:

• Utilized a sensor element with two piano-convex AT-cut quartz crystals vibrating in a thickness-shear mode.
• Positioned the liquid sample between the two quartz crystals to create a unique measurement environment.
• Monitored the fundamental resonance frequency and resonance Q-value of the quartz crystals, which are affected by the liquid's properties.

Main Results:

• The novel sensor design effectively suppresses disturbing resonances present in single-plate configurations.
• The sensor accurately measures the density-viscosity product of Newtonian liquids.
• Demonstrated successful measurements for liquids with viscosities ranging from near-zero to 200 centipoise (cP).

Conclusions:

• The described dual-crystal quartz sensor offers a reliable and accurate method for determining the density-viscosity product.
• The design effectively mitigates interference from compressional waves, enhancing measurement precision.
• This sensor is suitable for applications requiring precise rheological characterization with minimal sample volumes (130 microliters).