A Simple Capillary Blood Cell Flow Monitoring System using Magnetic Micro-Sensor: A Simulation Study

Since blood flow is a physiologically important parameter in determining the state of the tissue (e.g., viability and activity), various blood flow measurement techniques have been developed. However, existing blood flow measurement methods require complex equipment to generate external energy sources to be applied onto the tissue. This paper describes a magnetic method for the simple and external source-free measurement of blood flowing throughout the capillary. A microcoil located near to the capillary captures the intrinsic magnetic field produced by flowing negatively charged blood cells (e.g., red blood cells and white blood cells) to induce the electromotive force (EMF). The velocity of blood cells is estimated using the time interval between adjacent peaks and the slope of the induced EMF. The direction of blood flow can also be determined based on the frequency shift of the induced EMF. When moving the microcoil in the same direction of the blood flow, the frequency of induced EMF decreases, whereas an increased frequency is observed when moving the microcoil in the opposite direction to the blood flow. Moreover, this method could detect and distinguish streams of red blood cells and white blood cells. These results support the feasibility of a non-invasive magnetic blood flow monitoring system that does not require any external power source applied to the blood stream and thereby alleviates the complexity of conventional blood flow monitoring systems.