Quantum Dot-Based Optical Fiber Sensor for Flow Velocity Sensing at Low Initial Temperatures

Area of Science:

• Optoelectronics
• Materials Science
• Microfluidics

Background:

• Accurate flow velocity monitoring is vital for microfluidic systems and blood microcirculation.
• Conventional hot wire flowmeters require high initial temperatures, limiting their use with temperature-sensitive fluids like blood.

Purpose of the Study:

• To develop a fiber sensor probe for sensitive flow velocity detection in microfluidics.
• To overcome the limitations of high initial temperatures in existing hot wire flowmeters.

Main Methods:

• Fabrication of a fiber sensor probe with a plano-concave cavity using PbS quantum dots (QDs)-doped photoresist.
• Utilizing a 980 nm excitation laser for thermal energy conversion and C-band interference for detection.
• Implementing an intensity interrogation scheme for the fiber sensor probe.

Main Results:

• Achieved sensitive flow velocity monitoring with only a 3 °C temperature increase.
• Demonstrated a sensitivity of 7.7 pm/(mm/s) within a linear response range of 3.82 mm/s to 16.72 mm/s.
• The proposed sensor is suitable for microfluidics due to its low initial temperature requirement.

Conclusions:

• The developed fiber sensor probe offers a sensitive and low-temperature solution for microfluidic flow velocity measurement.
• This technology shows significant potential for applications in microcirculation monitoring and drug delivery systems.