METHOD UTILIZING TWO WIRE ELECTRODE OSCILLATOR SYSTEM FOR DETERMINING BODY IMPEDANCE

• US 20110015540A1
• Filed: 09/24/2010
• Published: 01/20/2011
• Est. Priority Date: 11/24/2004
• Status: Active Grant

• Current Assignee: Measurement Ltd (Measurement Ltd., Inc.)
• Original Assignee: Measurement Ltd (Measurement Ltd., Inc.)
• Inventors: Petrucelli, Steven
• Granted Patent: US 8,233,975 B2
• Time in Patent Office: Days
• US Class Current: 600/547
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body

Abstract

A method for measuring an impedance of a body includes the steps of electrically coupling first and second electrodes to the body and electrically biasing a variable frequency relaxation oscillator. The oscillator has both a positive resistive feedback network and a negative feedback network which includes the electrodes. The method further includes a step of measuring the period of oscillation of the variable frequency oscillator. The measured period of oscillation is indicative of the impedance of the body.

Claims

1. A method for calibrating an apparatus for determining body impedance having first and second electrodes being suitable for being electrically coupled to the body, comprising:

determining a first period of oscillation for the apparatus associated with an open circuit condition between the electrodes; and

determining a second period of oscillation for the apparatus associated with a short-circuit condition between the electrodes;

wherein, the first period of oscillation is indicative of a first calibration value, and the second period of oscillation in combination with a slope coefficient is indicative of a second calibration value.

2. The method of claim 1, wherein the slope coefficient is indicative of a calibration.

3. The method of claim 1, further comprising storing data indicative of the first period of oscillation.

4. A method for measuring an impedance of a body, comprising:

electrically coupling first and second electrodes to the body;

electrically biasing a variable frequency relaxation oscillator having both a negative feedback network comprising said electrodes, and a positive resistive feedback network; and

measuring the period of oscillation of said variable frequency oscillator, wherein the measured period of oscillation is indicative of the impedance of the body.

5. The method of claim 4, wherein the measured period of oscillation is proportional to the impedance of the body.

6. The method of claim 4, wherein the oscillator comprises at least one operational amplifier.

7. The method of claim 6, wherein the first of said electrodes is resistively coupled to an output terminal of said operational amplifier.

8. The method of claim 7, wherein the second of said electrodes is coupled to common through at least one capacitor and shorted to an inverting input terminal of said operational amplifier.

9. The method of claim 8, wherein said at least one capacitor charges and discharges exponentially through said electrodes with respect to said operational amplifier non-inverting input terminal.

10. The method of claim 4, further comprising the step of determining, by a microprocessor, the lean body mass of the body as a function of the weight of the body and the measured impedance of the body.

11. The method of claim 4, further comprising the step of determining, by a microprocessor, the lean body mass of the body as a function of the weight of the body, the measured impedance of the body and one or more of the height, a fitness factor, the sex and the age of the body.

12. The method of claim 11, wherein one or more coefficients for determining said lean body mass are stored in a memory accessible to the microprocessor and correspond to one or more of the height, the weight, the fitness factor, the measured impedance, the sex and the age of the body.

13. The method of claim 10, further comprising the step of determining, by the microprocessor, the percentage of body fat of the body, as a function of the lean body mass and the weight of the body.

14. The method of claim 10, further comprising the step of determining, by the microprocessor, the percentage of body fat of the body as a function of the lean body mass, the weight of the body and one or more of a fitness factor, the age and the sex of the body.

15. The method of claim 14, further comprising a step of determining the fitness factor, by the microprocessor, as a function of the measured impedance of the body and one or more values received by the microprocessor and pertaining to one or more body characteristics of the body.

16. The method of claim 15, wherein said one or more values pertaining to said one or more body characteristics of the body comprise values associated with the height, the sex, the age, the weight, an exercise frequency, an exercise type and an exercise intensity of the body.

17. The method of claim 14, wherein the fitness factor is a user input to the microprocessor.