SWITCH PROBE FOR MULTIPLE ELECTRODE MEASUREMENT OF IMPEDANCE

• US 20110282180A1
• Filed: 01/27/2009
• Published: 11/17/2011
• Est. Priority Date: 01/27/2009
• Status: Active Grant

• Current Assignee: Scibase AB (SciBase Holding AB)
• Original Assignee: Scibase AB (SciBase Holding AB)
• Inventors: Birgersson, Ulrik, Gunnarsson, Marcus, Goldkuhl, Fredrik
• Granted Patent: US 8,948,838 B2
• Time in Patent Office: Days
• US Class Current: 600/393
• CPC Class Codes: A61B 2562/043 in a linear array
• CPC Class Codes: A61B 5/0531 Measuring skin impedance
• CPC Class Codes: A61B 5/444 Evaluating skin marks, e.g. mole, nevi, tumour, scar
• CPC Class Codes: A61B 5/685 Microneedles

Abstract

The present invention provides impedance data having an improved spatial resolution, both with regard to depth and lateral extension, which enables a detection of diseased skin conditions, such a malignant melanoma, at an early stage. Specifically, the present invention is implemented in a probe, medical devices and medical systems including such a probe, and methods using such a probe for measuring electrical impedance of tissue of a subject. A switching circuit is arranged for selectively activate electrode pairs of the probe in accordance with a predetermined activation scheme, the predetermined activation scheme including to activate adjacent electrodes in a successive manner, to gradually scan tissue of the subject at a first tissue depth so as to obtain a sequence of impedance signals from the tissue depth.

Claims

1-32. -32. (canceled)

33. A probe for measuring electrical impedance of tissue of a subject comprising a plurality of electrodes, said probe being adapted to be placed in direct contact with the skin of the subject, and being connectable to an impedance measuring circuit adapted to apply a voltage and to measure a resulting current or to inject a current and to measure the resulting voltage to determine an impedance signal, further comprising:

a switching circuit for selectively activate electrode pairs by connecting at least two of electrodes with said impedance measuring circuit and disconnecting the remaining electrodes from said impedance circuit, wherein said voltage is applied at said two electrodes and said resulting current is measured between said at least two electrodes; and

wherein

said switching circuit is adapted to receive control signals instructing said switching circuit to activate electrode pairs in accordance with a predetermined activation scheme, said predetermined activation scheme including to activate adjacent electrodes in a successive manner to gradually scan tissue of said subject at least at a first tissue depth so as to obtain a sequence of impedance signals from said at least first tissue depth.

34. The probe according to claim 33, wherein said switching circuit is adapted to connect each electrode such that said electrode functions in one of at least three states including a first active state where said electrode is connected to the impedance measuring circuit to inject a current into or to apply a voltage at tissue of said subject, a second active state where said electrode is connected to said impedance measuring circuit to measure the resulting current or the resulting voltage from the tissue, and a floating state where said electrode is disconnected from said impedance measuring circuit.

35. The probe according to claim 34, wherein said switching circuit is adapted to activate electrodes in accordance with the predetermined activation scheme, said predetermined activation scheme including to activate two electrodes in said first state and in said second state and to place the remaining electrodes in said floating state in a successive manner to gradually scan a tissue of said subject at different tissue depths.

36. The probe according to claim 33, wherein said electrodes have an elongated rectangular shape and are arranged at said probe in parallel rows.

37. The probe according to claim 33, wherein said predetermined activation schedule includes to activate two electrodes in said first and second state, said electrodes having at least one electrode arranged in between, and to successively activate electrode pairs having at least one electrode arranged in between to gradually scan a tissue of said subject at a selected tissue depth, wherein said tissue depth can be adjusted by selecting a number of intermediate electrodes between said activated pair of electrodes.

38. The probe according to claim 33, wherein said switching circuit is adapted to connect each electrode such that said electrode may function in a fourth state, wherein said electrode is connected to ground.

39. The probe according to claim 38, wherein said switching circuit is adapted to disconnect at least one of the non-activated electrodes to place said electrodes in said floating state or to connect said electrodes to ground in said fourth state.

40. A measurement device for measuring electrical impedance of tissue of a subject comprising a probe having a plurality of electrodes, said electrodes being adapted to be placed in direct contact with the skin of the subject, and an impedance measuring circuit adapted to apply a voltage or to inject a current at two of said electrodes and to measure a resulting current or to measure a resulting voltage to determine an impedance signal, said measurement device further comprising:

a switching circuit for selectively activate electrode pairs by connecting at least two of electrodes with said impedance measuring circuit and disconnecting the remaining electrodes from said impedance circuit, wherein said voltage is applied at said two electrodes and said resulting current is measured between said at least two electrodes; and

a control device adapted to control said switching circuit to activate electrodes in accordance with a predetermined activation scheme, said predetermined activation scheme including to activate adjacent electrodes in a successive manner to gradually scan tissue of said subject at least at a first tissue depth so as to obtain a sequence of impedance signals from said at least first tissue depth.

41. The measurement device according to claim 40, wherein said control circuit is adapted to control said switching circuit to connect each electrode such that said electrode functions in one of at least three states including a first active state where said electrode is connected to the impedance measuring circuit to inject a measuring current into or to apply a voltage at tissue of said subject, a second active state where said electrode is connected to said impedance measuring circuit to measure the resulting current or the resulting voltage from the tissue, and a floating state where said electrode is disconnected from said impedance measuring circuit.

42. The measurement device according to claim 41, wherein said control device is adapted to activate electrodes in accordance with the predetermined activation scheme, said predetermined activation scheme including to activate two electrodes in said first state and in said second state and to place the remaining electrodes in said floating state in a successive manner to gradually scan a tissue of said subject at different tissue depths.

43. The measurement device according to claim 40, wherein said predetermined activation schedule includes to activate two electrodes in said first and second state, said electrodes having at least one electrode arranged in between, and to successively activate electrode pairs having at least one electrode arranged in between to gradually scan a tissue of said subject substantially corresponding to a probe surface at a selected tissue depth, wherein said tissue depth can be adjusted by selecting a number of intermediate electrodes between said activated pair of electrodes.

44. The measurement device according to claim 40, wherein said control circuit is adapted to control said switching circuit to connect each electrode such that said electrode may function in a fourth state, wherein said electrode is connected to ground.

45. The measurement device according to claim 44, wherein said control circuit is adapted to control said switching circuit to disconnect at least one of the non-activated electrodes to place said electrodes in said floating state or to connect said electrodes to ground in said fourth state.

46. A medical system for diagnosing a diseased condition of the skin of a subject comprising a probe for measuring electrical impedance of tissue of a subject, said probe being provided with a plurality of electrodes adapted to be placed in direct contact with the skin of the subject, comprising:

an impedance measuring circuit adapted to apply a voltage or to inject a current at two of said electrodes and to measure a resulting current or a resulting voltage to determine an impedance signal;

a switching circuit for selectively activate electrode pairs by connecting at least two of electrodes with said impedance measuring circuit and disconnecting the remaining electrodes from said impedance circuit, wherein said voltage is applied at said two electrodes and said resulting current is measured between said at least two electrodes;

a control device adapted to control said switching circuit to activate electrodes in accordance with a predetermined activation scheme, said predetermined activation scheme including to activate adjacent electrodes in a successive manner to gradually scan tissue of said subject at least at a first tissue depth so as to obtain a sequence of impedance signals from said at least first tissue depth; and

a diagnosing unit being adapted to obtain said sequence of impedance signals and to deliver a diagnosis of a diseased condition of the tissue based on the measured impedance signals and reference values.

47. The medical system in accordance with claim 46, wherein said system includes:

(1) a probe for measuring electrical impedance of tissue of a subject comprising a plurality of electrodes, said probe being adapted to be placed in direct contact with the skin of the subject, and being connectable to an impedance measuring circuit adapted to apply a voltage and to measure a resulting current or to inject a current and to measure the resulting voltage to determine an impedance signal, further comprising;

a switching circuit for selectively activate electrode pairs by connecting at least two of electrodes with said impedance measuring circuit and disconnecting the remaining electrodes from said impedance circuit, wherein said voltage is applied at said two electrodes and said resulting current is measured between said at least two electrodes; and

wherein

said switching circuit is adapted to receive control signals instructing said switching circuit to activate electrode pairs in accordance with a predetermined activation scheme, said predetermined activation scheme including to activate adjacent electrodes in a successive manner to gradually scan tissue of said subject at least at a first tissue depth so as to obtain a sequence of impedance signals from said at least first tissue depth wherein said switching circuit is adapted to connect each electrode such that said electrode functions in one of at least three states including a first active state where said electrode is connected to the impedance measuring circuit to inject a current into or to apply a voltage at tissue of said subject, a second active state where said electrode is connected to said impedance measuring circuit to measure the resulting current or the resulting voltage from the tissue, and a floating state where said electrode is disconnected from said impedance measuring circuit, or

(2) a measurement device for measuring electrical impedance of tissue of a subject comprising a probe having a plurality of electrodes, said electrodes being adapted to be placed in direct contact with the skin of the subject, and an impedance measuring circuit adapted to apply a voltage or to inject a current at two of said electrodes and to measure a resulting current or to measure a resulting voltage to determine an impedance signal, said measurement device further comprising;

a switching circuit for selectively activate electrode pairs by connecting at least two of electrodes with said impedance measuring circuit and disconnecting the remaining electrodes from said impedance circuit, wherein said voltage is applied at said two electrodes and said resulting current is measured between said at least two electrodes; and

a control device adapted to control said switching circuit to activate electrodes in accordance with a predetermined activation scheme, said predetermined activation scheme including to activate adjacent electrodes in a successive manner to gradually scan tissue of said subject at least at a first tissue depth so as to obtain a sequence of impedance signals from said at least first tissue depth.

48. A method of for diagnosing a diseased condition of the skin of a subject utilizing a probe for measuring electrical impedance of tissue of a subject, said probe being provided with a plurality of electrodes adapted to be placed in direct contact with the skin of the subject, comprising:

applying a voltage or injecting a current at two of said electrodes;

measuring a resulting current or a resulting voltage to determine an impedance signal;

selectively activating electrode pairs by connecting at least two of electrodes with said impedance measuring circuit and disconnecting the remaining electrodes from said impedance circuit, wherein said voltage is applied at said two electrodes and said resulting current is measured between said at least two electrodes;

gradually scanning tissue of said subject at least at a first tissue depth so as to obtain a sequence of impedance signals from said at least first tissue depth by controlling activation of electrodes in accordance with a predetermined activation scheme, said predetermined activation scheme including activating adjacent electrodes in a successive manner; and

delivering a diagnosis of a diseased condition of the tissue based on the measured impedance signals and reference values.

49. The method according to claim 48, further comprising connecting each electrode such that said electrode functions in one of at least three states including a first active state where said electrode is connected to an impedance measuring circuit to inject a current into or to apply a voltage at tissue of said subject, a second active state where said electrode is connected to said impedance measuring circuit to measure the resulting current or to measure the resulting voltage from the tissue, and a floating state where said electrode is disconnected from said impedance measuring circuit.

50. The method according to claim 48, further comprising activating electrodes in accordance with the predetermined activation scheme, said predetermined activation scheme including to activate two electrodes in said first state and in said second state and to place the remaining electrodes in said floating state in a successive manner to gradually scan a tissue of said subject at different tissue depths.

51. The method according to claim 48, wherein said predetermined activation schedule includes activating two electrodes in said first and second state, said electrodes having at least one electrode arranged in between, and to successively activating electrode pairs having at least one electrode arranged in between to gradually scan a tissue of said subject substantially corresponding to a probe surface at a selected tissue depth, wherein said tissue depth can be adjusted by selecting a number of intermediate electrodes between said activated pair of electrodes.

52. The method according to claim 50, further comprising connecting each electrode such that said electrode may function in a fourth state, wherein said electrode is connected to ground.

53. The method according to claim 52, further comprising disconnecting at least one of the non-activated electrodes to place said electrodes in said floating state or to connect said electrodes to ground in said fourth state.