Optimal Design to Ensure Maximum Coupling between Magnetic Flux and Arterial Blood in a Magneto Plethysmo Gram Sensor Head

Magneto plethysmo gram (MPG), like the Photo plethysmo gram (PPG) is a signal that carries information on blood volume flow and is obtained noninvasively. Unlike PPG, MPG is obtained from a peripheral artery, such as radial, carotid or brachial. The magnetic flux required for obtaining an MPG is generated by a permanent magnet placed on the wrist surface such that the generated flux couples with the blood flow in the artery. In this work it is shown that maximum coupling of flux with the blood flow in radial artery occurs when the distance between the open end of the U shaped probe is 12 mm. In order to attain this result, first the probe is simulated using the finite element method. The distance between the pole faces is varied in steps of 1 mm. Simulation results clearly indicate that the optimal distance is 12mm. Next experiments were conducted with prototype probes of varying distances between the pole faces on 20 volunteers of different age and gender. The experimental results validate the result obtained by the simulation study.