Magneto-Plethysmographic Sensor for Peripheral Blood Flow Velocity

In order to detect blood volume changes, we proposed the new magnetic plethysmographic sensor using time-varying magnetic fields, and thereby, measuring the change of impedance of exciting coil. The change of coil impedance was proportional to the change of blood volume passing through a volume-of-interests, which inductively coupled with exciting coil. In order to verify the feasibility of the proposed method, photo-plethysmographic and magneto-plethysmographic (MPG) signals were recorded from the index and middle finger of the left hand simultaneously. Comparison of the proposed sensor signals with ultrasound Doppler blood flow velocity recordings shows the excellent correlation (r = 0.9355, p <; 0.01) and the RR intervals derived from electrocardiograph and MPG signals showed a very high degree of correlation (r = 0.9823, p <; 0.01).