Lever-enabled milli-Newton mechanical force detection via a microbottle resonator

Area of Science:

• Photonics
• Mechanical Engineering
• Materials Science

Background:

• Whispering gallery mode resonators offer high sensitivity for sensing applications.
• Accurate measurement of small mechanical forces is crucial for biomedical and structural monitoring.

Purpose of the Study:

• To develop a milli-Newton mechanical force sensor with enhanced detection range and sensitivity.
• To investigate the use of a microbottle resonator (MBR) coupled with a tapered fiber for force sensing.

Main Methods:

• A lever model was established by coupling an MBR with a tapered fiber, with adjustable ratio of load arm to effort arm (RLE).
• Mechanical force was applied via capillary displacement, deforming the MBR and shifting its resonance wavelength.
• Theoretical deduction and experimental verification of capillary displacement dependence on mechanical force.

Main Results:

• A maximum sensitivity of -10.48 pm/mN and a resolution of 40 µN were achieved.
• The sensor demonstrated a detection range of 0-4 mN, tunable by RLE.
• The MBR's radius deformation directly correlated with applied mechanical force.

Conclusions:

• The developed MBR-based force sensor offers high sensitivity, resolution, and a flexible detection range.
• Easy fabrication and adaptable structure make it suitable for biomedical and structural health monitoring.
• This technology provides a novel approach for precise mechanical force measurement.