Patent ID: 7680524
Filing Date: 2010-03-16
Classification: A61B,G01R

Abstract:
1. A magnetic fluid detection method comprising: a step in which a magnetic fluid possessing magnetism is injected from the outside into a substance in which the fluid can flow; an excitation step in which a direct-current or alternating-current magnetic field for exciting said magnetic fluid is applied; a measurement step in which the variation in the magnetic field strength caused by the applied magnetic field is measured in two or more places that are close to each other, the measurement of the variation of the magnetic field strength is of a component of the magnetic field strength that is perpendicular to the applied magnetic field, a distance between the magnetic field strength measurement places is set approximately equal to the substantial size of the areas where the magnetic fluid accumulates; a calculation step in which the absolute value or amplitude value of signals measured in said measurement step is calculated; and a search step in which a search is made for a portion of the substance where said calculation step shows a maximum value by interlockingly varying a position of the magnetic field application in the excitation step and the magnetic field strength measurement in the measurement step; wherein said portion of said substance in which the largest amount of the magnetic fluid has accumulated are identified by measuring the distortion of the local magnetic field distribution that results from the fact that the specific magnetic permeability of said magnetic fluid is higher than that of the surrounding substance.