Switch probe for multiple electrode measurement of impedance

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, said measurement device further comprising:

• an impedance measuring circuit;
• a switching circuit for selectively connecting each electrode with said impedance measuring circuit, wherein said impedance measuring circuit is adapted to apply a voltage between two active electrodes and measure a resulting current flowing between said two active electrodes, or to inject a current flowing between said two active electrodes and measure a resulting voltage between said two active electrodes, to determine an impedance signal;
• and 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 said current into or to apply said voltage to the 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
• an inactive state where said electrode is disconnected from said impedance measuring circuit;
• and
• a control device adapted to control said switching circuit to activate electrode pairs, one active electrode in said first active state and the other active electrode in said second active state to form the two active electrodes connected to the impedance measuring circuit, and to deactivate remaining electrodes by switching the remaining electrodes to the inactive state, in accordance with a predetermined activation scheme, said predetermined activation scheme including to activate said electrode pairs and deactivate said remaining 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 electrode pairs are made of adjacent electrodes.

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;
• a switching circuit for selectively connecting each electrode with said impedance measuring circuit, wherein said impedance measuring circuit is adapted to apply a voltage between two active electrodes and measure a resulting current flowing between said two active electrodes, or to inject a current flowing between said two active electrodes and measure a resulting voltage between said two active electrodes, to determine an impedance signal;
• and 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 said current into or to apply said voltage to the 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
• an inactive state where said electrode is disconnected from said impedance measuring circuit;
• a control device adapted to control said switching circuit to activate electrode pairs, one active electrode in said first active state and the other active electrode in said second active state to form the two active electrodes connected to the impedance measuring circuit, and to deactivate remaining electrodes by switching the remaining electrodes to the inactive state, in accordance with a predetermined activation scheme, said predetermined activation scheme including to activate said electrode pairs and deactivate said remaining 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 electrode pairs are made of adjacent electrodes;
• 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 sequence of impedance signals and reference values.

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;
• a switching circuit for selectively connecting each electrode with said impedance measuring circuit, wherein said impedance measuring circuit is adapted to apply a voltage between two active electrodes and measure a resulting current flowing between said two active electrodes, or to inject a current flowing between said two active electrodes and measure a resulting voltage between said two active electrodes, to determine an impedance signal;
• and 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 said current into or to apply said voltage to the 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
• an inactive state where said electrode is disconnected from said impedance measuring circuit, said inactive state comprising a third floating state wherein said electrode is disconnected and a fourth state wherein said electrode is connected to ground,
• a control device adapted to control said switching circuit to activate electrode pairs, one active electrode in said first active state and the other active electrode in said second active state to form the two active electrodes connected to the impedance measuring circuit, and to deactivate remaining electrodes by switching the remaining electrodes to the inactive state, in accordance with a predetermined activation scheme, said predetermined activation scheme including to activate said electrode pairs and deactivate said remaining electrodes in a successive manner to gradually scan tissue of said subject at a selected tissue depth so as to obtain a sequence of impedance signals from said selected tissue depth,
• wherein said electrode pairs are made of adjacent electrodes or two electrodes having at least one intermediate electrode arranged in between, wherein said selected tissue depth is determined by selecting a number of intermediate electrodes;
• 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 sequence of impedance signals and reference values.

A method for diagnosing a diseased condition of the skin of a subject utilizing a probe for measuring electrical impedance of tissue of the subject, said probe being provided with a plurality of electrodes adapted to be placed in direct contact with the skin of the subject, and wherein each electrode is adapted to function 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 to said tissue;
• a second active state where said electrode is connected to said impedance measuring circuit to measure a resulting current or a resulting voltage from the tissue;
• and an inactive state where said electrode is disconnected from said impedance measuring circuit;
• said method comprising:
• placing the electrodes on the skin of the subject;
• selectively activating electrode pairs with one active electrode in said first active state and the other active electrode in said second active state to form two active electrodes connected to the impedance measuring circuit and deactivating remaining electrodes by switching the remaining electrodes to the inactive state, in accordance with a predetermined activation scheme;
• using said impedance measuring circuit to apply a voltage between said two active electrodes and measure said resulting current flowing between said two active electrodes, or to inject a current to flow between said two active electrodes and measure a resulting voltage between said two active electrodes, to determine an impedance signal;
• gradually scanning said 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 said 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 sequence of impedance signals and reference values.