Optical Fiber Sensor for Jugular Venous Pulse Waveforms Measurement

This article deals with the physical principle of operation of the optical fiber sensor, a description of its construction, use, and an analysis of the interference signal that the sensor provides when measuring the pulse pressure wave in the jugular vein. The interference signal is created in the reflected light due to the reflection from the low-finesse Fabry-Perot cavity composed of the front end of the optical fiber and a flexible membrane. The flexible membrane of the sensor is applied to the pulse area of the jugular vein, where the operational range is maintained by limiting skin compression to approximately 1 mm to preserve signal visibility. By phase demodulation of the interference signal using an extrema-detection algorithm, a measurement resolution of λ/4 (approximately 388 nm) is achieved. The obtained jugular venous pulse waveform carries information about the state of the right side of the heart, specifically revealing characteristic a, c, v peaks and x, y descents. The operation of the sensor, which is specifically optimized for high-sensitivity detection of low-pressure venous signals, was verified on five healthy human subjects by simultaneously measuring the interference signal and a synchronized electrocardiogram. A comparison of the obtained jugular venous pulse waveforms with electrocardiogram signals showed that the waveforms contain all significant physiological features. The results demonstrate that the described sensor allows obtaining jugular venous pulse waveforms in a simple, accurate way for use in the diagnosis of heart diseases.