Patent ID: 6449563
Filing Date: 2002-09-10
Classification: G01N

Abstract:
A device for determining the colloid vibration signals in concentrated dispersions with fluid medium, comprising:a piezoelectric device to convert a radio frequency pulse into an acoustic pulse; a delay rod, preferably quartz, receiving said acoustic pulse and introducing said pulse into a buffer rod; a buffer rod, preferably of plastic material that has an acoustic impedance similar to said concentrated dispersion, receiving said pulse from said delay rod and introducing said pulse into said concentrated dispersion; a circular electrode, preferably gold, deposited on the central portion of the end-face of said buffer rod such that it intercepts a significant portion of said acoustic pulse passing into said concentrated dispersion, and being in immediate contact with the colloid eliminates any uncertainty in the amplitude and phase of the CVI signal that would occur if the electrode was located any finite distance from the end of the buffer rod; an insulated spacer, preferably of some rugged plastic or a machineable ceramic, in which said piezoelectric device, said delay rod, said buffer rod, and said circular electrode are positioned such that only the circular electrode and the end-face of said insulated housing are in contact with said dispersion; a shell, preferably of stainless steel, in which said insulated spacer is positioned such that the annular end-face of said shell intercepts very little of the acoustic pulse and thus serves essentially as a reference electrode without creating any resonant behavior in the sensor that would occur if this reference electrode was located inside the sound field at some distance into the colloid; a control unit connected to said piezoelectric device which provides said radio frequency pulses, measures the reflected signals from the interface between said delay rod and said buffer rod, and measures the colloid vibration signals generated between said circular electrode and said reference electrode; calculating a normalized CVI signal taking into account any variation in the transducer efficiency with frequency or time, by utilizing the reflected signal from the interface between the delay rod and the buffer rod as a reference level pulse.