Simultaneous Measurement of Heart Sound, Pulse Wave and Respiration with Single Fiber Bragg Grating Sensor

Heart sound, pulse wave and respiration are simultaneously measured with single fiber Bragg grating(FBG) sensor. The FBG sensor is inscribed in optical fiber so that it is quite thinner than conventional electrical sensor, even enough to be weaved in clothes. In this study, single FBG sensor is taped near the Tricuspid area and on the carotid artery with the surgical tape. Measured data is denoised through digital Butterworth filter with low pass filter (0.2 Hz), medium frequency band pass filter (0.5 Hz - 5.0 Hz) and higher frequency bandpass filter (35.0 Hz - 55.0 Hz) to extract the information of respiration, pulse wave and heart sound, respectively. The lower frequency signal follows the reference respiration sensor. The medium and higher frequency signal contains the features of typical pulse wave and heart sound waveform. The pulse wave measured on precordium contains the feature of apex cardiogram. The result also indicate that the timing of the heart sound is slightly delayed on the carotid artery. These results indicate the possibility of wearable, continuous vital sigh measurement system.