Novel fiber-tip micro flowmeter based on optofluidic microcavity filled with silver nanoparticles solutions

Area of Science:

• Optofluidics
• Nanotechnology
• Optical Sensing

Background:

• Accurate measurement of microfluidic flow is crucial in various scientific and industrial fields.
• Existing micro flowmeters often face limitations in sensitivity, robustness, or applicability in confined spaces.
• Optofluidic systems offer unique advantages for developing miniaturized sensing devices.

Purpose of the Study:

• To propose and demonstrate a novel fiber-tip micro flowmeter.
• To utilize the opto-thermal effect of silver nanoparticle solutions (SNS) for flow sensing.
• To achieve high sensitivity and robustness in micro-scale flow rate measurements.

Main Methods:

• Fabrication of a fiber-tip microcavity filled with SNS.
• Heating the SNS using a continuous wave (CW) fiber laser to induce an opto-thermal effect.
• Monitoring the shift in Fabry-Perot interference spectrum dips caused by temperature-induced refractive index changes in SNS.
• Correlating spectral shifts with microfluidic flow velocity.

Main Results:

• The developed sensor exhibits a maximum flow rate sensitivity of 1.5 nm/(μL/s) over a range of 0-5 μL/s.
• A low detection limit (DL) of 0.08 μL/s was achieved.
• The fiber-tip micro flowmeter demonstrated strong robustness and suitability for measurements in confined spaces.
• The silver nanoparticle solution showed excellent biological compatibility.

Conclusions:

• The proposed optofluidic micro flowmeter offers a sensitive, robust, and miniaturized solution for microfluidic flow rate measurement.
• The device leverages the opto-thermal properties of silver nanoparticles for precise sensing.
• Potential applications include haematology, oil prospecting, ocean dynamics, and drug research due to its performance and biocompatibility.