Free-access optomechanical liquid probes using a twin-microbottle resonator.

Area of Science:

• Cavity optomechanics
• Nanoscale sensing technology
• Fluid dynamics

Background:

• Cavity optomechanics offers high-performance sensor technology applicable to liquid samples.
• Existing methods using fluidic channels or droplets lack active sample access due to fixed designs.

Purpose of the Study:

• To develop an alternate probe-based optomechanical sensor architecture for active, free access to liquid samples.
• To enable in situ metrology in arbitrary media for biological and rheological applications.

Main Methods:

• Utilized a probe with a twin-microbottle resonator, immersing one bottle in liquid for detection and keeping the other in air for readout.
• Employed high optical Q (~10^7) for the readout bottle to maintain detection performance.
• Implemented detection of thermomechanical motion and optomechanical drive with frequency tracking via a phase-locked loop.

Main Results:

• Demonstrated a probe-based optomechanical sensor enabling detection in liquid samples.
• Achieved excellent detection performance through the high-Q readout resonator.
• Successfully tracked thermomechanical motion and optomechanical drive with frequency tracking.

Conclusions:

• The developed technique provides active, free access to liquid samples for sensing.
• This approach enables in situ metrology in arbitrary media.
• Potential applications include ultrasensitive biochips and rheometers.