Device for determining the electric potential of the brain

Abstract

A device for determining a physiological or psychological state of a mammal is disclosed. The device has at least one earpiece with a main body having a body of revolution with an axis of revolution, and an endpiece configured to be inserted into an ear canal. The endpiece has a cylindrical channel intended to receive a body of revolution for detachably mounting the endpiece on the main body, the endpiece being arranged to be movable in rotation about the axis of revolution in order to allow at least one electrode to be oriented toward a zone of the brain of the mammal, and the endpiece having a plurality of electrodes arranged on an outer surface of the endpiece, each electrode being configured to pick up an electrical signal in the ear canal of the mammal.

1 . A device ( 100 ,  200 ,  400 ) for determining a physiological or psychological state of a mammal, the device ( 100 ,  200 ,  400 ) comprising at least one earpiece ( 402 ) comprising:
 a main body ( 102 ) comprising a body of revolution ( 110 ) having an axis of revolution ( 108 ), and   an endpiece ( 104 ,  220 ,  700 ) configured to be inserted into an ear canal ( 404 ), said endpiece ( 104 ,  220 ) having a cylindrical channel ( 112 ) intended to receive the body of revolution ( 110 ) for detachably mounting the endpiece ( 104 ,  220 ) on the main body ( 102 ), the endpiece ( 104 ,  220 ) being arranged to be movable in rotation about the axis of revolution ( 108 ) in order to allow at least one electrode ( 106 ) to be oriented toward a zone of the brain of the mammal, and said endpiece ( 104 ,  220 ) comprising a plurality of electrodes ( 106 ;  701 - 703 ) arranged on an outer surface of the endpiece ( 104 ,  220 ), each electrode ( 106 ;  701 - 703 ) being configured to pick up an electrical signal in the ear canal of the mammal, and   said device comprising first electrical tracks ( 118 ,  202 ) electrically insulated from each other, arranged in the cylindrical channel ( 112 ) of the endpiece ( 104 ,  220 ) and connected to the electrodes ( 106 ), and second electrical tracks ( 116 ,  204 ) electrically insulated from each other, arranged in the cylindrical part ( 110 ) of the main body ( 102 ) and intended to convey the electrical signal, picked up by the electrodes ( 106 ), to a calculation means ( 115 ),   in which each of the first electrical tracks, or each of the second electrical tracks, has an annular shape having as its axis said axis of revolution and is arranged in electrical contact with one of said first electrical tracks ( 118 ,  202 ), or one of said second electrical tracks, independently of the orientation of the endpiece about said axis of revolution, and said first electrical tracks ( 118 ,  202 ) or second electrical tracks ( 116 ,  204 ) of annular shape being spaced along said axis of revolution ( 108 ).   
     
     
         2 . The device ( 100 ,  200 ,  400 ) as claimed in  claim 1 , in which at least one electrode ( 106 ) has an outer part extending over a longitudinal part, in the direction of the axis of revolution ( 108 ), of the outer surface of the endpiece ( 104 ,  220 ). 
     
     
         3 . The device ( 100 ,  200 ,  400 ) as claimed in  claim 1 , in which at least one electrode ( 106 ) has an inner part extending over a part of the cylindrical channel ( 112 ) in order to form a first electrical track. 
     
     
         4 . The device ( 100 ) as claimed in  claim 1 , in which each of the second electrical tracks ( 116 ) is annular, and each of the first electrical tracks ( 118 ) is configured to come into contact with a respective second annular electrical track ( 116 ). 
     
     
         5 . The device ( 100 ) as claimed in  claim 4 , in which each of the first electrical tracks ( 118 ) extends in an arc of a circle on the inner part of the cylindrical channel ( 112 ) about the axis of revolution ( 108 ). 
     
     
         6 . The device ( 200 ) as claimed in  claim 1 , in which each of the first electrical tracks ( 202 ) is annular, and each of the second electrical tracks ( 204 ) forms a contact pad configured to come into contact with a respective first annular electrical track. 
     
     
         7 . The device ( 400 ) as claimed in  claim 1 , in which the device ( 400 ) comprises two earpieces ( 402 ,  402 ′) configured to be arranged in a first mammalian ear canal ( 404 ) and a second mammalian ear canal ( 404 ′), respectively, and intended to convey respective electrical signals to the calculation means ( 115 ),
 said calculation means ( 115 ) being suitable for determining the physiological or psychological state as a function of a signal picked up by an electrode ( 106 ) of the earpiece ( 402 ) arranged in the first ear canal ( 404 ) and a signal measured by an electrode ( 106 ′) of the earpiece ( 402 ′) arranged in the second ear canal ( 404 ′), in particular as a function of a difference between the two signals. 
 
     
     
         8 . The device ( 100 ,  200 ,  400 ) as claimed in  claim 1 , in which the device comprises a calculation means ( 115 ) configured to determine a physiological or psychological state of a mammal as a function of the electrical signals picked up by the electrodes ( 106 ). 
     
     
         9 . The device ( 100 ,  200 ,  400 ) as claimed in  claim 8 , in which the plurality of electrodes ( 106 ) comprises a reference electrode ( 703 ) and at least one measuring electrode ( 702 ), and in which the calculation means ( 115 ) is configured to determine the physiological or psychological state as a function of at least one difference between the electrical signal picked up by one of the measuring electrodes ( 702 ) and the electrical signal picked up by the reference electrode ( 703 ). 
     
     
         10 . The device ( 100 ,  200 ,  400 ) as claimed in  claim 9 , in which the plurality of electrodes comprises, in addition to the reference electrode ( 703 ) and the at least one measuring electrode ( 702 ), a ground electrode ( 701 ), said ground electrode being oriented toward a specific part of the ear canal, said specific part of the ear canal making it possible to pick up a stable signal. 
     
     
         11 . The device ( 100 ,  200 ,  400 ) as claimed in  claim 10 , in which the endpiece ( 104 ,  220 ,  700 ) is constructed so as to be able to be in contact with the specific part of the ear canal when inserted into the ear canal, and in which the ground electrode ( 701 ) is located on a part of the endpiece ( 104 ,  220 ,  700 ) in contact with the specific part of the ear canal, in order to pick up an electrical signal on said specific part of the ear canal. 
     
     
         12 . The device ( 100 ,  200 ,  400 ) as claimed in  claim 10 , in which the specific part of the ear canal is a mammalian tragus. 
     
     
         13 . The device ( 100 ,  200 ,  400 ) as claimed in  claim 10 , in which processing means ( 114 ,  620 ) use the signal picked up by the ground electrode ( 701 ) to effect a noise reduction in the signals measured by the reference electrode ( 703 ) and the at least one measuring electrode ( 702 ). 
     
     
         14 . The device ( 100 ,  200 ,  400 ) as claimed in  claim 13 , in which the noise reduction is achieved by means of a common-mode rejection circuit ( 621 ). 
     
     
         15 . The device ( 100 ,  200 ,  400 ) as claimed in  claim 13 , in which the processing means comprise two voltage generators ( 606 ,  607 ), and the ground electrode ( 701 ) is connected to a potential corresponding to half the sum of the voltages delivered by the two voltage generators ( 606 ,  607 ). 
     
     
         16 . The device ( 100 ,  200 ,  400 ) as claimed in  claim 15 , in which the processing means comprise a first resistor ( 605 ) connected to a first voltage generator ( 607 ) and arranged in such a way as to receive the electrical signal picked up by the reference electrode, and a second resistor ( 604 ) connected to a second voltage generator ( 606 ) and arranged in such a way as to receive the electrical signal picked up by the at least one measuring electrode, the second voltage generator delivering a voltage greater than that delivered by the first voltage generator. 
     
     
         17 . The device ( 100 ,  200 ,  400 ) as claimed in  claim 9 , in which the electrodes ( 106 ,  702 ,  703 ) are spaced apart from each other in a circumferential direction about the axis of revolution ( 108 ). 
     
     
         18 . The device ( 100 ,  200 ,  400 ) as claimed in  claim 9 , additionally comprising processing means ( 114 ,  620 ) including two voltage generators ( 606 ,  607 ), and in which the reference electrode ( 703 ) is connected to a potential corresponding to half the sum of the voltages delivered by the two voltage generators ( 606 ,  607 ). 
     
     
         19 . The device ( 100 ,  200 ,  400 ) as claimed in  claim 18 , in which the reference electrode is intended to be oriented toward a mastoid of the mammal upon insertion of the endpiece into the ear canal of the mammal. 
     
     
         20 . The device ( 100 ,  200 ,  400 ) as claimed in  claim 18 , in which the endpiece ( 104 ,  220 ) has a marking configured for visually recognizing the reference electrode. 
     
     
         21 . The device ( 100 ,  200 ,  400 ) as claimed in  claim 1 , comprising a selector configured to receive the electrical signals from the electrodes, said selector being configured to detect a reference electrode, among the electrodes ( 106 ), said reference electrode being selected as the electrode emitting the electrical signal having the most stable electrical potential among the electrical signals picked up by the electrodes ( 106 ). 
     
     
         22 . The device ( 100 ,  200 ,  400 ) as claimed in  claim 1 , in which the endpiece ( 104 ,  220 ) comprises a polymer material, and at least one electrode ( 106 ) comprises a conductive fabric embedded or recessed in the polymer material of the endpiece. 
     
     
         23 . The device ( 100 ,  200 ,  400 ) as claimed in  claim 1 , in which the endpiece ( 104 ,  220 ) comprises a polymer material, and at least one electrode ( 106 ) comprises a conductive material selected from conductive polymers and silicone doped with nanoparticles, embedded or recessed in the polymer material of the endpiece. 
     
     
         24 . The device ( 100 ,  200 ,  400 ) as claimed in  claim 1 , in which the main body ( 102 ) comprises wired or wireless data transmission means ( 308 ) configured to communicate with the calculation means ( 115 ). 
     
     
         25 . The device ( 100 ,  200 ,  400 ) as claimed in  claim 1 , in which the device comprises a means for filtering the electrical signals, said means being configured to attenuate parasitic signals detected by one or more of said electrodes. 
     
     
         26 . The device ( 100 ,  200 ,  400 ) as claimed in  claim 25 , in which the filtering means comprises a band-pass filter ( 306 ) having a pass band between 0.3 Hz and 50 Hz, in particular between 1 Hz and 40 Hz. 
     
     
         27 . The device ( 100 ,  200 ,  400 ) as claimed in  claim 1 , in which the calculation means is configured to:
 determine an electroencephalogram signal of the mammal as a function of the electrical signals measured,   determine an amplitude of at least one brain wave in a predefined frequency range as a function of said electroencephalogram signal, and   determine a psychological state as a function of said amplitude of at least one brain wave by comparing said amplitude with a predetermined threshold.   
     
     
         28 . The device ( 100 ,  200 ,  400 ) as claimed in  claim 1 , in which the physiological or psychological state relates to an electrical activity of an organ of the mammal, selected from the group consisting of a brain, a heart, a nerve, a muscle and an eye. 
     
     
         29 . The device ( 100 ,  200 ,  400 ) as claimed in  claim 1 , in which the physiological or psychological state is mammalian fatigue, a mammalian attention level or a mammalian epileptic seizure.