Method and Device for Determining a Parameter of Living Tissue

• US 20080057526A1
• Filed: 06/07/2004
• Published: 03/06/2008
• Est. Priority Date: 06/07/2004
• Status: Active Grant

• Current Assignee: Biosigns Pte Limited, Pendragon Medical AG
• Original Assignee: Biovotion AG (Biofourmis AG)
• Inventors: Ryabov, Yaroslav, Caduff, Andreas, Truffer, Pascal
• Granted Patent: US 8,200,307 B2
• Time in Patent Office: Days
• US Class Current: 435/14
• CPC Class Codes: A61B 5/0531 Measuring skin impedance
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement

Abstract

A device for measuring a glucose level or some other parameter of living tissue that affects the dielectric properties of the tissue is disclosed. The device comprises an electrode arrangement (5) having a plurality of electrodes (5-i). The signal from a signal source (31) can be applied to the electrode arrangement via a switching assembly (39). The switching assembly (39) is designed to selectively connect a first and a second pattern of the electrodes (5-i) to the signal source, thereby generating a first and a second electrical field with different spatial distribution in the tissue. By using a differential method which relies on measuring the impedance of the electrode arrangement (5) for each field and on suitable subtraction of the measured results, surface effects can be reduced and the focus of the measurement can be offset to a point deeper inside the tissue.

Claims

1. A device for measuring a parameter of living tissue, in particular a glucose level, which parameter affects a response of said tissue to an electric field, comprising

an electrode arrangement (5),

a signal source (31) generating an electrical signal to be applied to said electrode arrangement (5) for generating an electrical field in said tissue, and

a detector (37, 38) for measuring a response from said tissue to said electrical field and for determining at least one parameter therefrom,

wherein said device is adapted to generate at least two spatially different electrical fields (E₁, E₂) in said tissue, and wherein said detector is adapted to determine said parameter from a difference of the responses of said tissue to said spatially different electrical fields.

2. The device of claim 1, wherein said electrode arrangement (5) comprises at least three electrodes (5-i), wherein said device is adapted to generate said at least two spatially different electrical fields (E₁, E₂) by first applying a first voltage pattern to said electrodes (5-i) and by then applying a second voltage pattern to said electrodes (5-i), wherein said first and said second voltage patterns are different.

3. The device of claim 2, further comprising a switching assembly (39) arranged between said signal source (31 ) and said electrodes (5-i) for selectively connecting at least a first and a second pattern of said electrodes (5-i) to said signal source (31).

4. The device of claim 1, wherein said electrode arrangement (5) comprises a plurality of electrodes (5-i) arranged side by side.

5. The device of claim 4, wherein said electrode arrangement (5) comprises at least four, in particular at least eight, electrodes (5-i) arranged side by side.

6. The device of claim 4, wherein said device is adapted to selectively apply

in a first mode of operation, a first voltage pattern to said electrodes (5-i) , wherein in said first voltage pattern the electrodes of each pair of neighboring electrodes carry different voltages, and

in a second mode of operation, a second voltage pattern to said electrodes (5-i) , wherein in said second voltage pattern a the electrodes of a first part of the pairs of neighboring electrodes carry equal voltages and the electrodes of a second part of the pairs of neighboring electrodes carry different voltages.

7. The device of claim 1, wherein detector (37, 38) is adapted

to measure a first measured value s₁ indicative of the response of said tissue to a first electrical field and a second measured value S₂ indicative of the response of said tissue to a second electrical field, wherein said first and said second electrical field are spatially different, and

to calculate a weighted difference k1·

s1−

k2·

s2 with weights k1 and k2, wherein the weights are chosen such that a non-constant contribution of the dielectric response of an epidermis of the tissue to the weighted difference is minimized.

8. The device of claim 1, wherein said electrode arrangement (5) comprises a plurality of electrodes (5-i) and wherein said detector (37, 38) is adapted for measuring values depending on a capacitance (C), and/or resistance (R) and/or impedance (Z) of at least two different combinations of the electrodes.

9. The device of claim 1, wherein said parameter is a glucose level in the tissue.

10. A method for measuring a parameter of living tissue, in particular a glucose level, which parameter affects a response of said tissue to an electric field, comprising the steps of

applying an electrode arrangement (5) to said tissue,

applying a first electrical signal to said electrode arrangement (5) for generating a first electrical field in said tissue and detecting a first response of said tissue to said first electrical field,

applying a second electrical signal to said electrode arrangement (5) for generating a second electrical field in said tissue and detecting a second response of said tissue to said second electrical field, wherein said first and said second electrical fields are spatially different,

determining said parameter from a difference of the first and the second response of said tissue.