Method for measuring of edema
First Claim
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1. A method for measuring tissue edema, comprising:
- placing an open-ended coaxial probe on a skin surface;
transmitting an electromagnetic field through the skin surface;
measuring a capacitance of the probe, wherein the measured capacitance of the probe is proportional to a dielectric constant of skin tissue and subcutaneous fat tissue, which is further proportional to a water content of the skin tissue and the subcutaneous fat tissue, the probe having two concentric electrodes separated by a distance configured such that the electromagnetic field penetrates past the skin tissue to the subcutaneous fat tissue underneath the skin tissue, wherein said distance is 6 mm to 10 mm, wherein said distance is along a radial direction, wherein the two concentric electrodes comprise an inner electrode and outer electrode, and wherein said distance is from an outer edge of the inner electrode to an inner edge of the outer electrode;
scoring the edema by measuring the capacitance of the probe at a frequency of 20-500 MHz.
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Abstract
The invention relates to a method for measuring tissue edema. By a method in accordance with the invention an electromagnetic probe (24) is placed on the skin, and the capacitance of the probe is proportional to the dielectric constant of the skin and subcutaneous fat, which is proportional to the water content of the skin. The edema is scored by measuring the capacitance of the electromagnetic probe, so called open-ended coaxial cable, at a high frequency, approximately 20-500 MHz.
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Citations
20 Claims
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1. A method for measuring tissue edema, comprising:
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placing an open-ended coaxial probe on a skin surface; transmitting an electromagnetic field through the skin surface; measuring a capacitance of the probe, wherein the measured capacitance of the probe is proportional to a dielectric constant of skin tissue and subcutaneous fat tissue, which is further proportional to a water content of the skin tissue and the subcutaneous fat tissue, the probe having two concentric electrodes separated by a distance configured such that the electromagnetic field penetrates past the skin tissue to the subcutaneous fat tissue underneath the skin tissue, wherein said distance is 6 mm to 10 mm, wherein said distance is along a radial direction, wherein the two concentric electrodes comprise an inner electrode and outer electrode, and wherein said distance is from an outer edge of the inner electrode to an inner edge of the outer electrode; scoring the edema by measuring the capacitance of the probe at a frequency of 20-500 MHz. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A device for measuring tissue edema, which device includes
an open-ended coaxial probe configured to be placed on a skin surface during the measurement wherein a capacitance of the probe is proportional to a dielectric constant of the skin tissue and subcutaneous fat tissue, which is further proportional to a water content of the skin tissue and the subcutaneous fat tissue, a plurality of high frequency components configured to measure the capacitance of the probe, wherein the plurality of high frequency components are arranged to measure the capacitance of the probe at a first range of 20-50 MHz, wherein the first range corresponds to a measure of an upper part of a dermis, wherein the plurality of high frequency components are arranged to measure the capacitance of the probe at a second range of 50-500 MHz, and wherein the second range corresponds to a measure of a lower part of the dermis and the subcutaneous fat tissue, a calculating unit configured to calculate the dielectric constant and the tissue edema, and the probe having two concentric electrodes separated by a distance, the distance between the two electrodes of the probe configured such that the electromagnetic field penetrates past the skin tissue and into the subcutaneous fat tissue, wherein said distance is 6 mm to 10 mm, wherein said distance is along a radial direction, wherein the two concentric electrodes comprise an inner electrode and outer electrode, and wherein said distance is from an outer edge of the inner electrode to an inner edge of the outer electrode.
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19. A method for measuring tissue edema comprising:
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placing an open-ended coaxial probe on a skin surface, wherein the probe comprises two electrodes, wherein the two electrodes are concentric, wherein a distance separating the two electrodes of the probe is 6-10 mm, wherein said distance is along a radial direction, wherein the two concentric electrodes comprise an inner electrode and outer electrode, and wherein said distance is from an outer edge of the inner electrode to an inner edge of the outer electrode; generating a first signal from an oscillator, wherein a frequency of the first signal is 20 to 500 MHz; transmitting a first portion of the first signal to the probe and through the skin tissue and subcutaneous fat tissue; receiving a reflected signal from the skin tissue and subcutaneous fat tissue through the probe; leading the reflected signal to a first input of a phase detector; transmitting a second portion of the first signal to a second input of the phase detector, operating the phase detector in a saturated state, wherein signal amplitudes from the reflected signal and the second portion of the first signal form the saturated state; measuring a phase difference between the reflected signal and the second portion of the signal; calculating a dielectric constant from the phase difference; calculating a water content of the skin tissue and the subcutaneous fat tissue based on the dielectric constant; and detecting edema based on, at least partially, the water content. - View Dependent Claims (20)
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Specification