Optical Fiber Fabry-Pérot Microfluidic Sensor Based on Capillary Fiber and Side Illumination Method

Area of Science:

• Optoelectronics
• Microfluidics
• Optical Fiber Sensing

Background:

• Microfluidic sensors are crucial for analyzing small sample volumes.
• Simultaneous measurement of refractive index and temperature is challenging but vital for accurate concentration analysis.

Purpose of the Study:

• To design and demonstrate a hybrid Fabry-Pérot (HFP) microfluidic sensor.
• To achieve simultaneous measurement of microfluidic refractive index (RI) and temperature.
• To validate the sensor's performance for in situ monitoring in biomedical and biochemical fields.

Main Methods:

• Fabrication of an HFP sensor using capillary fiber (CF) and side-illumination.
• Utilizing the CF as a microfluidic channel and the inner air hole/silica wall as the FP cavity.
• Employing a cross-sensitivity matrix method for simultaneous RI and temperature measurement.
• Analyzing interference spectra using Fast Fourier Transform (FFT) with bandpass filtering.

Main Results:

• The HFP sensor demonstrated simultaneous RI and temperature sensing capabilities.
• The sensor exhibited excellent temperature compensation.
• Three sensors with varying inner air hole diameters were fabricated and characterized.
• The sensor is low-cost, easy to build, and suitable for high-precision sensing.

Conclusions:

• The proposed optical fiber microfluidic sensor enables accurate, simultaneous measurement of RI and temperature.
• This technology is well-suited for in situ monitoring of drug concentration and optical constants in micro-specimens.
• The sensor offers a cost-effective and high-performance solution for biomedical and biochemical applications.