Optical spectral sweep comb liquid flow rate sensor.

Area of Science:

• Photonics and Sensing
• Microfluidics
• Optical Fiber Sensors

Background:

• Accurate flow rate measurement is critical for microfluidic chip applications.
• Existing flowmeters often lack the sensitivity required for low flow rates.

Purpose of the Study:

• To develop a simple and highly sensitive liquid flow rate sensor for microfluidics.
• To utilize a tilted fiber Bragg grating (TFBG) as the core sensing element.

Main Methods:

• A TFBG was employed as the sensing element, with liquid flow occurring along the fiber axis.
• Spectral changes of the TFBG upon water contact were analyzed.
• A spectral sweep comb was generated by comparing time-swept spectra to determine flow rate.

Main Results:

• The sensor demonstrated a high Q-value (>17,000) and a wide detectable range (0.0058 mm/s to 3.2 mm/s).
• Achieved a lower detectable flow rate of 0.03 nL/s, three orders of magnitude better than current fiber flowmeters.
• The sensor exhibits inherent temperature self-compensation.

Conclusions:

• The proposed TFBG sensor provides a simple, sensitive, and accurate method for low flow rate measurements in microfluidics.
• This configuration opens new avenues for TFBG-based sensor development for microfluidic applications.
• The sensor's performance and temperature self-compensation capabilities make it suitable for demanding microfluidic systems.