Pulled microcapillary tube resonators with electrical readout for mass sensing applications.

Area of Science:

• Materials Science
• Nanotechnology
• Sensor Technology

Background:

• Microfabrication techniques for hollow resonators are complex and costly.
• Development of accessible and efficient mass sensing platforms is crucial for various applications.

Purpose of the Study:

• To present a microfabrication-free approach for creating hollow channel mass sensors.
• To demonstrate the sensor's capability in measuring liquid density and droplet size distributions.
• To validate the performance of the proposed sensor system.

Main Methods:

• A glass capillary was pulled and suspended on a jig to create a pulled micro capillary tube resonator (PμTR).
• A piezo actuator excited the PμTR, and a quartz tuning fork (QTF) sensed its resonance frequency.
• Electrical and optical measurements validated the resonant spectra. Liquid samples were introduced to measure resonance frequency shifts with density changes.

Main Results:

• The PμTR demonstrated a density responsivity of -3,088 Hz-g⁻¹cm³, comparable to microfabricated hollow resonators.
• The system successfully measured the size distribution of oil droplets in water with a radius resolution of 31 nm.
• The resonant mass sensing system utilized off-the-shelf components with convenient electrical readout.

Conclusions:

• The microfabrication-free approach offers a simple and cost-effective method for fabricating hollow channel mass sensors.
• The developed sensor system is capable of precise liquid density and droplet size measurements.
• This technology provides a convenient and accessible resonant mass sensing solution.