Noninvasive electromagnetic fluid level sensor
AssigneeZevex, Inc.
InventorDavid Blaine
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Abstract
A disposable sensor is disclosed for non-invasively detecting and characterizing a container's contents. By generating microwave frequency signals, electromagnetic fields are produced by a sensor and penetrate a container. The EM fields are analyzed in regards to how they are perturbed by the container contents. Analysis of the perturbed EM fields enables determination of content level, content purity, content density, content temperature, container pressure, and content conductivity.
Claims53
A sensor system for use in characterizing contents of a container, wherein said sensor system analyzes microwave frequency electromagnetic signals generated therefrom to thereby determine characteristics of the container contents, said system comprising:
- an electromagnetic sensor which is disposable on a container, and which is capable of transmitting the microwave frequency electromagnetic signals, wherein the electromagnetic sensor is a microwave frequency multi-port coupler which includes an input port and at least two output ports, wherein a high common mode rejection ratio is used to thereby reduce electromagnetic sensor activity by having a first output port and a second output port;
- a detector circuit which is electrically coupled to the electromagnetic sensor to thereby detect the perturbations in the microwave frequency electromagnetic signals, and which processes each signal from the first and the second output ports by rectifying, integrating, and then comparing the rectified and integrated signals using a differential amplifier circuit;
- a processing device which is electrically coupled to the electromagnetic sensor, wherein the processing device develops the microwave frequency electromagnetic signals to be transmitted, analyzes the transmitted microwave frequency electromagnetic signals to thereby detect perturbations therein, and provide a human perceptible alarm when the detected perturbations indicate that an alarm condition is met;
- wherein the processing device includes an oscillator which is electrically coupled to the electromagnetic sensor, and which develops the microwave frequency electromagnetic signals for transmission therefrom;
- a controller for activating the oscillator and the detector circuit when the electromagnetic sensor is in a sensing mode, and for deactivating the oscillator and the detector circuit when the sensor system is in a sleep mode, and wherein a duration of the sensing and the sleep modes is programmable;
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- a power supply for supplying electrical current to the sensor system.
A method for characterizing contents of a container using a sensor system, wherein said method includes analyzing microwave frequency electromagnetic signals which are generated by an electromagnetic sensor to thereby determine characteristics of the container contents, said method comprising the steps of:
- (1) disposing the electromagnetic sensor, which is capable of transmitting the microwave frequency electromagnetic signals, on a container;
- (2) developing the microwave frequency electromagnetic signals in a processing device which is electrically coupled to the electromagnetic sensor, and transmitting said signals from the electromagnetic sensor, wherein the microwave frequency electromagnetic signals are generated utilizing an oscillator which is electrically coupled to the electromagnetic sensor;
- (3) utilizing a detector circuit which is electrically coupled to the electromagnetic sensor to thereby detect the perturbations in the microwave frequency electromagnetic signals;
- (4) activating the oscillator and the detector circuit when the electromagnetic sensor is in a sensing mode;
- (5) analyzing the transmitted microwave frequency electromagnetic signals to thereby detect perturbations therein;
- (6) utilizing at least a 3-port coupler as the microwave frequency electromagnetic sensor, wherein the 3-port coupler has a first output port and a second output port, and wherein the detector circuit processes each signal from the first and the second output ports of the 3-port coupler by rectifying, integrating, and then comparing the rectified and integrated signals from the first and the second output ports using a differential amplifier circuit which amplifies any difference between each signal, wherein the sensor system has a high common mode rejection ratio to thereby reduce sensor system sensitivity, and wherein the detector circuit will minimize an influence of external factors so that the detector circuit can determine whether an alarm condition exists;
- (7) providing a human perceptible alarm when the detected perturbations indicate that an alarm condition is met;
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- (8) deactivating the oscillator and the detector circuit when the sensor system is in a sleep mode.
Dependencies are inferred from the claim text.