Contactless Arrhythmia Detection and Short-Term HRV Analysis Based on a Fiber Optic Sensor

Accurate detection of premature atrial contractions (PACs) is crucial for identifying life-threatening arrhythmias. Traditional electrocardiogram (ECG) devices, which require electrodes attached to the body, often cause discomfort and are unsuitable for long-term monitoring. This article presents a noncontact ballistocardiogram (BCG) monitoring system utilizing a fiber optic sensor (FOS) for PAC identification and short-term heart rate variability (HRV) analysis. The system employs a Mach–Zehnder interferometer (MZI), which is simple and easy to replicate, consisting of only a 1 × 2 coupler and a 3 × 3 coupler. Tiny body vibrations caused by breathing and heartbeats lead to changes in the intensity of the interference light. By detecting these changes using three photodetectors (PDs), vital sign signals can be captured. To evaluate the robustness of the PAC detection algorithm, the study introduced fixed-speed breathing at two respiratory frequencies, increasing the range of interbeat interval (IBI) variations. The correlation coefficient between BCG-derived IBI and ECG-derived IBI in subjects with PAC was 0.9475. The proposed algorithm achieved an accuracy of 94.84% in PAC detection. Additionally, the time- and frequency-domain results of BCG-derived HRV and ECG-derived HRV showed high correlation at respiratory rates of 6 and 15 beats per minute (bpm), respectively. The FOS-based BCG signal not only accurately identifies PACs but also facilitates the HRV analysis. This proposed system is suitable for long-term, noncontact vital sign monitoring in daily life.