Split resonances for simultaneous detection and control measurements in a single bulk acoustic wave (BAW) sensor

Area of Science:

• Materials Science
• Nanotechnology
• Sensor Technology

Background:

• Resonators are crucial for sensing applications.
• Device-to-device variability in fabrication affects measurement accuracy.
• Existing methods struggle to mitigate fabrication-induced frequency variations.

Purpose of the Study:

• To develop a self-referenced resonator for accurate mass sensing.
• To minimize the impact of device-to-device variability on measurements.
• To introduce a new method for measuring mass attachment using frequency differences.

Main Methods:

• Fabrication of a resonator with two distinct top electrode areas (Mo and Au).
• Utilizing shear (~1 GHz) and longitudinal (~2 GHz) resonant modes.
• Analyzing frequency shifts upon mass attachment to the functional layer.

Main Results:

• Fundamental frequencies for both shear and longitudinal modes are split.
• Mass attachment on the functional layer shifts only one resonance frequency.
• A new approach using the difference between split frequencies for mass measurement is demonstrated.

Conclusions:

• The self-referenced resonator effectively measures mass attachment.
• The method significantly reduces reliance on absolute resonant frequency, mitigating fabrication variability.
• This approach offers enhanced accuracy and reliability in mass sensing applications.