A lateral field excited liquid acoustic wave sensor.

Area of Science:

• Materials Science
• Analytical Chemistry
• Physical Chemistry

Background:

• Standard quartz crystal microbalances (QCM) are widely used for sensing applications.
• Limitations exist in QCM sensitivity, particularly in liquid environments, for detecting subtle changes in mechanical and electrical properties.
• Lateral Field Excited (LFE) sensors offer a potential improvement by modifying electrode placement.

Purpose of the Study:

• To fabricate and evaluate Lateral Field Excited (LFE) AT-cut quartz acoustic wave sensors for liquid environments.
• To investigate the sensitivity of LFE sensors to changes in liquid viscosity, relative permittivity, and conductivity.
• To compare the performance of LFE sensors with standard Quartz Crystal Microbalance (QCM) sensors.

Main Methods:

• Fabrication of 5-MHz LFE AT-cut quartz acoustic wave sensors with varying electrode spacings.
• Testing sensors in liquid environments with controlled variations in viscosity, relative permittivity, and conductivity.
• Analysis of sensor response to determine sensitivity to mechanical and electrical property changes.

Main Results:

• LFE sensors demonstrated significantly increased sensitivity to liquid property changes compared to standard QCM.
• Sensitivity to viscosity was more than double that of standard QCM.
• Sensitivity to relative permittivity and conductivity was approximately 1.5 times that of modified QCM sensors.

Conclusions:

• LFE sensors exhibit superior performance in detecting changes in liquid viscosity, permittivity, and conductivity.
• The design allows the electric field to penetrate the liquid, enhancing sensitivity.
• LFE sensors show promise for diverse liquid-phase sensing applications requiring high sensitivity.