Advanced Microfluidic Photonic Sensor Based on Precision Integrated Fiber Probe

In microfluidic systems, slight changes can lead to vital performance differences, accurate microfluidic monitoring is essential to ensure that the microfluidic device is working properly and achieving its intended function. A reflective long-period fiber grating (LPFG) probe for microflow monitoring is designed and demonstrated, by periodically embedding a multi-mode fiber (MMF) into a single-mode fiber (SMF) and integrating a metal mirror at the end. This design not only solves the inherent problem that LPFG can only receive transmitted light, but also reduces the overall structure by half, providing an attractive solution for the design of high precision microflow monitoring probes. The experimental results show that the liquid level and temperature resolution of LPFG probe in microfluidic monitoring are 5.72 μm and 0.29°C. The maximum error of temperature and volume (liquid level) accuracy detection in the randomized experiment is 0.4 μL and 0.06°C, which has an admirable precision and accuracy. It is also significant that miniaturized photonic sensors are more conducive to integration in chips. This innovative work provides an original idea for the function upgrade and integration of LPFG components, which has an attractive application prospect in the integration of photonics technology and microflow system.