High sensitivity all-fiber Michelson interferometer respiratory sensor based on PVA-coated down-taper

Area of Science:

• Fiber Optic Sensors
• Biomedical Engineering
• Wearable Technology

Background:

• Accurate and non-invasive respiratory monitoring is crucial for diagnosing and managing various medical conditions.
• Existing wearable sensors often face challenges with sensitivity, comfort, and long-term durability.
• Advancements in fiber optic sensing offer potential for developing next-generation physiological monitoring devices.

Purpose of the Study:

• To propose and characterize a novel wearable breathing sensor based on a single-mode fiber (SMF)-down-taper-Panda polarization-maintaining fiber (PMF) structure.
• To evaluate the sensor's performance in terms of sensitivity, repeatability, and correlation with commercial devices.
• To assess the sensor's suitability for real-time healthcare monitoring applications.

Main Methods:

• Fabrication of a fiber optic sensor incorporating an SMF-down-taper-PMF structure with a PVA-coated taper and a fiber sphere.
• Characterization of the sensor's sensitivity to curvature, temperature, and humidity.
• In-vivo testing on human volunteers to measure respiratory rates and assess performance metrics.
• Comparison of sensor data with readings from commercial respiratory monitoring devices.

Main Results:

• The sensor achieved high sensitivity with specific values for curvature (34.8508 dB/m^-1), temperature (0.0034 dB/°C), and humidity (0.5742 nm/%RH).
• Reliable detection of respiratory rates (0.21-0.41 Hz) was demonstrated with <8% repeatability error.
• A high Pearson correlation coefficient (>0.9) was observed when compared to commercial sensors.
• The sensor exhibited a fast response time with 1.06 s rise and 1.19 s recovery times.

Conclusions:

• The developed wearable breathing sensor demonstrates high sensitivity, excellent repeatability, and fast response, making it a promising tool for healthcare monitoring.
• The unique fiber optic structure and PVA coating enhance coupling efficiency and sensor durability.
• The sensor's comfort and reliable performance in detecting respiratory rates support its potential for widespread clinical adoption.