Integrated microfluidic flowmeter based on a micro-FBG inscribed in Co²⁺-doped optical fiber

Area of Science:

• Optoelectronics
• Microfluidics
• Fiber Optics

Background:

• Microfluidic devices require precise flow rate measurement for various applications.
• Traditional flowmeters can be bulky and unsuitable for miniaturized systems.
• Optical fiber sensors offer high sensitivity and small form factors.

Purpose of the Study:

• To develop and demonstrate a novel microfluidic flowmeter.
• To integrate a microfiber Bragg grating (µFBG) as a flow sensing element.
• To achieve high sensitivity flow rate detection in microchannels.

Main Methods:

• Fabrication of a tapered optical fiber with a µFBG inscribed in a Co²⁺-doped fiber.
• Integration of the µFBG within a microfluidic channel formed by stacked capillaries.
• Utilizing a 1480 nm laser to locally heat the µFBG, functioning as a miniature hot-wire anemometer.
• Measuring microfluidic flow rate via the wavelength shift of the µFBG.

Main Results:

• Successful fabrication of a microfluidic flowmeter incorporating a µFBG.
• Demonstrated flow rate sensing capabilities with a minimum detectable change of approximately 16 nL/s.
• The µFBG acts as a sensitive flow sensor when locally heated by a laser.

Conclusions:

• The developed µFBG-based microfluidic flowmeter offers high sensitivity and a compact design.
• This technology shows significant potential for integration into lab-on-a-chip and biochip systems.
• The miniature hot-wire flowmeter principle applied to µFBG is effective for microfluidic applications.