Research on fiber Bragg grating heart sound sensing and wavelength demodulation method

Abstract

Heart sound includes a lot of physiological and pathological information of heart and blood vessel. Heart sound detecting is an important method to gain the heart status, and has important significance to early diagnoses of cardiopathy. In order to improve sensitivity and reduce noise, a heart sound measurement method based on fiber Bragg grating was researched. By the vibration principle of plane round diaphragm, a heart sound sensor structure of fiber Bragg grating was designed and a heart sound sensing mathematical model was established. A formula of heart sound sensitivity was deduced and the theoretical sensitivity of the designed sensor is 957.11pm/KPa. Based on matched grating method, the experiment system was built, by which the excursion of reflected wavelength of the sensing grating was detected and the information of heart sound was obtained. Experiments show that the designed sensor can detect the heart sound and the reflected wavelength variety range is about 70pm. When the sampling frequency is 1 KHz, the extracted heart sound waveform by using the db4 wavelet has the same characteristics with a standard heart sound sensor.

Wireless, Portable Fiber Bragg Grating Interrogation System Employing Optical Edge Filter

“…Further, FBG sensors are much thinner than conventional electrical sensors, with almost the same diameter as a hair, and can be woven into textiles [15,16]. Considering these advantages, several studies have investigated the use of FBG sensors in vital sign monitoring [17,18,19,20,21,22]. For example, ballistocardiograph (BCG), seismocardiograph (SCG) and respiration are measured using Magnetic Resonance Imaging (MRI) [23,24,25], in which the sensors are exposed to strong electromagnetic fields.…”