Electrode and a Method for Determining Electrical Biopotentials

Abstract

A set of electrodes suitable for being attached to the skin of an animal or human being at locations normally used for attaching single-lead electrodes with a single sensor point. The electrodes of the set of electrodes have at least three sensors arranged to define two linearly independent directions, which allows sensing corresponding electrical potential differences in the two directions. Signals representing sensed potential differences can be transmitted wirelessly or via conductors to a processing apparatus for being transformed into electrical potentials that approximate traditional potentials obtained with wired single-sensor electrodes. A method is also presented.

1 . A set comprising at least two disposable electrodes, said electrodes being of the type for sensing electrical potentials on the skin of an animal or human being and where each of said at least two disposable electrodes comprises
 a carrier,   at least three sensors carried by the carrier and arranged so that lines through centres of respective pairs of sensors define at least two linearly independent directions,   means for detachably attaching the electrode to the skin of an animal or human being with the sensors in electrical contact with the skin, and   connections to external equipment for transmitting respective sensed electrical potentials from the sensors to the external equipment.   
     
     
         2 . A set of electrodes according to  claim 1 , characterized in that the sensors of each of said at least two electrodes are all within an area that can be covered by an electrode with a single sensor normally used for sensing the electrical potentials on animals and human beings. 
     
     
         3 . A set of electrodes according to  claim 1 , characterized in that each of said at least two electrodes has a size that allows a plurality of the electrodes to be attached to the skin of a patient at respective locations normally used for sensing the electrical potentials, without any of the electrodes overlapping each other. 
     
     
         3 . A set of electrodes according to  claim 1 , characterized in that the sensors of each of said at least two electrodes are all located within the periphery of a circle with a diameter of 70 mm or less. 
     
     
         4 . A set of electrodes according to any one of  claims 1 - 3  wherein the at least two linearly independent directions of each of said at least two electrodes are perpendicular to each other. 
     
     
         5 . A set of electrodes according to any one of  claims 1 - 4  characterized in that each of said at least two electrodes has a visual indication of a predetermined orientation of the electrode. 
     
     
         6 . A set of electrodes according to  claim 5  characterized in that said visual indication on each of said at least two electrodes references an anatomical feature of the body. 
     
     
         7 . An electrode suitable for a set of electrodes according to  claims 5  or  6 . 
     
     
         8 . A system for sensing electrical potentials at predetermined locations on the skin of an animal or human being, the system comprising a set of electrodes according to anyone of  claims 1 - 6  and a number of wireless transmitters equal to the number of electrodes, where each transmitter is adapted to receive sensed electrical potentials from the sensors and to transmit signals corresponding to the sensed electrical potentials. 
     
     
         9 . A method for sensing electrical potentials at predetermined locations on the skin of an animal or human being, the method comprising
 arranging, in each of the predetermined locations, an electrode from the electrode set according to any one of  claims 1 - 6 ,   connecting to each of the electrodes a wireless transmitter adapted to receive sensed electrical potentials from the sensors and to transmit signals representing the sensed electrical potentials, and   receiving from each transmitter the signals transmitted therefrom.   
     
     
         10 . A method of determining the electrical potential of a first location (A) on the skin of an animal or human being relative to a reference location (R) on the skin of an animal or human being, the method comprising the steps of:
 attaching, to each of the first location (A) and the reference location (R) an electrode, each electrode having at least three sensors arranged so that lines through centres of respective pairs of sensors define two linearly independent directions,   sensing, with each of the sensors on each electrode, an electrical potential on the skin,   transmitting signals representing at least two differences between pairs of potentials sensed with corresponding pairs of sensors on each electrode,   receiving the transmitted signals, and   determining the electrical potential at the first location (A) relative to the reference location (R) based on the received signals.   
     
     
         11 . A method according to  claim 10  further comprising determining parameters representing the instantaneous amplitude of a bioelectrical field in the animal or human being. 
     
     
         12 . A method according to  claim 10  further comprising determining parameters representing the instantaneous polarity of a bioelectrical field in the animal or human being. 
     
     
         13 . A method according to  claim 10  further comprising determining parameters representing the instantaneous direction of propagation of a bioelectrical field in the animal or human being. 
     
     
         14 . A method of determining the electrical potential at a first location (A) relative to a reference location (R) on the skin of an animal or human being, the method comprising
 attaching to each of the first (A) and reference (R) locations an electrode from a set of electrodes according to any one of  claims 1 - 6     at the first location (A):
 sensing an electrical potential (VA r ) in a first reference position, 
 sensing an electrical potential (VA dirX ) in a position in a first direction from the first reference position, 
 determining a first electrical potential difference (VA dirX )−(VA r ) between the electrical potential (VA dirX ) in the position in the first direction from the first reference position and the electrical potential (VA r ) in the first reference position, 
 sensing an electrical potential (VA dirY ) in a position in a second direction from the first reference position, 
 determining a second electrical potential difference (VA dirY )−(VA r ) between the electrical potential (VA dirY ) in the second direction from the first reference position and the electrical potential (VA r ) in the first reference position, 
 transmitting signals representing the first and second electrical potential difference; 
   at the reference location (R):
 sensing an electrical potential (VR r ) in a second reference position, 
 sensing an electrical potential (VR dirX ) in a position in a third direction from the second reference position, 
 determining a third electrical potential difference (VR dirX )−(VR r ) between the electrical potential (VR dirX ) in the third direction from the second reference position and the electrical potential (VR r ) in the second reference position, 
 sensing an electrical potential (VR dirY ) in a position in a fourth direction from the second reference position, 
 determining a fourth electrical potential difference (VR dirY )−(VR r ) between the electrical potential (VR dirY ) in the fourth direction from the second reference position and the electrical potential (VR r ) in the second reference position, and 
 transmitting signals representing the third and fourth electrical potential difference, 
   receiving the transmitted signals, and   determining the electrical potential of the first location (A) relative to the reference location (R) based on the first, second, third and fourth potential differences.   
     
     
         15 . A method according to  claim 14  wherein the electrical potential of the first location (A) relative to the reference location (R) is based on the difference between the size of a first vector defined by the instantaneous first and second electrical potential differences and the size of a reference vector defined by the instantaneous third and fourth electrical potential differences. 
     
     
         16 . A method according to  claim 14  wherein the electrical potential of the first location (A) relative to the reference location (R) is based on the difference between the size of a first vector defined by the integrated first and second electrical potential differences and the size of a reference vector defined by the integrated third and fourth electrical potential differences. 
     
     
         17 . A method according to  claim 14  wherein the electrical potential of the first location (A) relative to the reference location (R) is based on the difference between the time integrated magnitude of a first vector defined by the instantaneous first and second electrical potential differences and the time integrated magnitude of a reference vector defined by the instantaneous third and fourth electrical potential differences. 
     
     
         18 . A method according to  claim 14 , characterized in that the electrode arranged at the first location and the electrode arranged at the reference location are oriented such that the two linearly independent directions (X, Y) defined by the electrode at the first location (A) are substantially the same as the two linearly independent directions (X, Y) of the electrode at the reference location (R). 
     
     
         19 . A method according to  claim 18 , characterized in that the electrical potential of the first location (A) relative to the reference location (R) is determined as the sum of
 a first difference between the first electrical potential difference and the third electrical potential difference and   a second difference between the second electrical potential difference and the fourth electrical potential difference.   
     
     
         20 . A method according to  claim 18 , characterized in that the electrical potential of the first location (A) relative to the reference location (R) is determined as the sum of
 a first difference between the integration of the first electrical potential difference and the integration of the third electrical potential difference and   a second difference between the integration of the second electrical potential difference and the integration of the fourth electrical potential difference.   
     
     
         21 . A method according to  claim 18 , characterized in that the electrical potential of the first location (A) relative to the reference location (R) is determined as the sum of
 a first difference between a moving average of the first electrical potential difference and a moving average of the third electrical potential difference and   a second difference between a moving average of the second electrical potential difference and a moving average of the fourth electrical potential difference.   
     
     
         22 . A system comprising a microprocessor which performs the receiving and the calculations steps of the method according to any one of  claims 9  to  21 .