Ultrasonic coagulation monitor and method
First Claim
1. A ultrasonic coagulation monitor, comprising:
- a housing,at least one piezoelectric crystal mounted in said housing,means for driving said crystal at a fixed frequency,a timer, andmeans for measuring resonant voltage in a circuit defined by said crystal and said driving means and for turning off said timer upon said voltage dropping to a predetermined level.
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Accused Products
Abstract
An ultrasonic coagulation monitor for measurement of prothrombin times and related coagulation times includes at least one piezoelectric crystal operated at a fixed frequency near its resonant frequency. A sample of material to be analyzed is placed in acoustic communication with the crystal. The voltage across the crystal is monitored in order to detect a voltage change, preferably a drop, that occurs upon coagulation of the sample. A timer is included that is turned off at a predetermined voltage drop corresponding to a particular stage of coagulation desired to be timed. In an alternative embodiment of the invention a second crystal is included and is mounted a predetermined distance from the first crystal to define a cavity therebetween. One crystal is driven by the frequency oscillator circuit and the material the coagulation of which is to be measured is placed in the cavity. A voltage sensing device senses the voltage across the second crystal and controls a timer as in the first embodiment.
65 Citations
29 Claims
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1. A ultrasonic coagulation monitor, comprising:
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a housing, at least one piezoelectric crystal mounted in said housing, means for driving said crystal at a fixed frequency, a timer, and means for measuring resonant voltage in a circuit defined by said crystal and said driving means and for turning off said timer upon said voltage dropping to a predetermined level. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A device for measuring coagulation times, comprising:
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at least one piezoelectric crystal, means for supporting each said crystal to allow each said crystal to oscillate in the plane of each said crystal, means for defining with said crystal a fixed frequency oscillator circuit, a timer, and means for measuring a change in resonance voltage in said oscillator circuit and for turning off said timer upon said resonance voltage changing to a predetermined value. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22)
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23. An ultrasonic coagulation monitor, comprising:
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a pair of piezoelectric crystals; means for mounting said crystals a predetermined distance apart to define a cavity therebetween; means for energizing at least one of said crystals with a fixed frequency oscillator circuit; a timer; and means for sensing a voltage at the other of said piezoelectric crystals and turning off said timer upon said voltage reaching a predetermined amplitude. - View Dependent Claims (24, 25, 26)
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27. A method of monitoring coagulation times of material comprising the steps of:
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placing material, the coagulation time of which is to be measured, in sound absorbing relationship with at least one piezoelectric crystal; driving said at least one crystal at a fixed frequency using a fixed frequency oscillator circuit; detecting a predetermined voltage change in said oscillator circuit; and determining the time required for the voltage change to occur. - View Dependent Claims (28, 29)
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Specification