Abstract:
There is disclosed a system of electrodes used for transdermal conduction of electrical signals and a method of use thereof, the system comprising a plurality of electrode parts connected by means of electrical conductors to electric impedance tomography apparatuses, as well as other devices, the parts being secured to an outer side of a flexible and porous blade coated on both sides thereof by layers of electrically conductive and adhesive materials, such electrically conductive and adhesive materials being in mutual contact through the pores of the blade, the inner face of the latter being removably secured, by means of adhesion, to the patient. The invention comprises means for positioning the electrode parts, as well as means for external protection thereof and of their respective conductors.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a divisional of U.S. patent application Ser. No. 13/132,300, filed Aug. 15, 2011, pending, which application is a national phase entry under 35 U.S.C. §371 of International Patent Application PCT/BR2009/000414, filed Dec. 18, 2009, designating the United States of America and published in English as International Patent Publication WO 2010/069023 A2 on Jun. 24, 2010, which claims the benefit under Article 8 of the Patent Cooperation Treaty and under 35 U.S.C. §119(e) to Brazilian Patent Application Serial No. PI0805365-0, filed Dec. 19, 2008, the disclosure of each of which is hereby incorporated herein in its entirety by this reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to the electrodes used to apply transdermal electrical stimuli to patients and/or to detect electrical signals from patients, such as sets of electrodes used in electrical impedance tomography, however, without being limited to the latter. 
       DESCRIPTION OF THE PRIOR ART 
       [0003]    The medical application of electrodes connected to specific equipment intended for electrical stimulation or detection of electrical signals comprehends both the application of currents or voltages through the skin, examples thereof comprising transcutaneous nerve or muscle stimulation and functional electrical stimulation, such as the detection of electrical signals exemplified by the electrocardiogram, the electroencephalogram, and the electromyiogram, as well as techniques whereby is applied an electrical signal through the skin, simultaneously measuring the resulting signals, as occurs with electrical impedance tomography. 
         [0004]    The electrical impedance tomography—generally known by the acronym EIT: Electrical Impedance Tomography—is an already known technique which consists of placing a plurality of electrodes in contact with the skin of the patient on a given region, and performing a series of steps comprising the injection of a current between the electrodes of a pair of electrodes, measuring the electrical potentials of the remaining electrodes, and repeating this step for all the electrodes of the entire set of electrodes. The measured values are sent to data processing equipment and are subjected to a treatment, which results in an image showing the electrical impedance within the region of interest. 
         [0005]    Contrary to other techniques used to follow up the conditions of the patient, the EIT is suitable for continuously monitoring the condition of the patient, due to being non-invasive and due to not involving risks that might limit the number and frequency of monitoring actions, such as occurs, for example, with X-rays. 
         [0006]    Since the distance between the points on the skin whereto the electrodes are attached may vary, either due to the effects of the patient&#39;s breathing (in the case of thoracic or abdominal monitoring) or even due to movements from the part of the patient, it is necessary that the electrode supporting element, normally configured as a strap, be capable of following these movements, in order to warrant permanent contact between the electrodes and the skin. Patent Application No. BR PI0704408, of the same filing applicant of the instant application, illustrated in  FIGS. 1 and 2  of the instant application, shows an electrode strap formed of a strip of fabric, both flexible and non-conductive, folded over itself in the longitudinal direction, resulting in a first section turned towards the patient and a second section oriented in the opposite direction, that is, externally to the patient. At spaced locations along the first section there is deposited a flexible conductive material, selectively in order to form a plurality of first circular or oblong regions or zones  34 , intended to contact the skin of the patient. Each of these zones  34  has an extension  24  which extends towards the fold, surrounding the same and extending over the second section whereon it broadens forming a second zone  27 , approximately coincident with the first zone. This second zone  27  serves to provide the electrical and mechanical connection to the points of contact  12  of a flexible, insulating and longitudinally non-deformable supporting strip  10 , each point of contact  12  being connected, by means of a flexible conductive track  39  embedded in the supporting strip  10 , to a connector  42  that is provided with means of contact with the cabling that connects the strap to the monitoring apparatus. 
         [0007]    As may be observed in  FIGS. 1 and 2 , the structure in question is complex, which manufacture involves the performance of cutting/opening of windows  33  and intermediary spaces  37  between the first zones  34 , as well as between the second zones  27  in the fabric material, in addition to the selective placement of the conductive material, the installation of the supporting strip  10 , etc. 
         [0008]    Moreover, the absence of shielding means of the flexible tracks  39  might entail the detection of interfering signals, thereby compromising the accuracy of the results. One other disadvantage of the object of the cited application resides in the act of there being required the manual application of a conductive gel material on the zones  34  in order to improve the electrical contact with the skin of the patient. 
         [0009]    There are presently known in the art several alternatives for the preparation of electrodes that dispense the manual application of such gels. In this regard, in U.S. Pat. No. 5,785,040, entitled Medical Electrode System, there is disclosed a system comprising a flexible, non-conductive backing material, having juxtaposed to the face turned towards the patient a plurality of patches made of a conductive material which face a flexible non-conductive blade. The latter is provided with openings or windows in the positions corresponding to the pads, with dimensions slightly lesser than the same. Through such windows, each of these conductive patches contacts the upper side of a conductive gel plate, which lower face adheres to the skin of the patient. The conduction of electrical signals is provided by flexible cables whose ends are permanently secured to the faces of the conductive pads turned towards the flexible backing material. Due to this last characteristic, the assembly cannot be washed, which fact compromises the reuse thereof. It is an expensive solution in light of its complex structure, and its application is limited. 
         [0010]    In U.S. Pat. No. 6,788,979, entitled Electrical Stimulation Compress Kit there is disclosed a system whereby a flexible insulating strap, equipped with a VELCRO®-type closure means, is applied by tightening around a part of the body of a patient, exerting a compressive force thereon. At certain points, this strap is crossed through by metallic terminals of a fastener type which outer pin provides a point for attachment for the terminal of the cable that conducts the electrical signals. The inner face of each terminal establishes an electrical contact with a conductive hook-loop fastener, which is removably attached to the strap by the adhesion of a first conductive gel layer. A second layer of conductive gel is in contact with the skin of the patient, the second layer being separated by a conductive web that may be made of metal or any other low resistivity material. This conductive web becomes necessary due to the small size of the area of the terminal turned towards the patient, which might result in a concentration of the transcutaneous current. The conductive web provides a uniform distribution of the current throughout the entire surface of the pad, reducing the contact resistance with the skin and avoiding the occurrence of current concentration points. In addition to the disadvantage represented by the need to use the pads, the described system has the disadvantage that the strap, in contact with the skin, is liable to become contaminated by sweat and other secretions; the washing or sterilization of the strap poses problems due to the presence of the metallic terminals and the VELCRO®-type adhesive means. The alternative, consisting in the mere disposal of the strap, constitutes a liability for the users of this system. 
       OBJECTS OF THE INVENTION 
       [0011]    In view of what has been set forth above, one object of the present invention consists in the provision of a system of electrodes combining low cost and easy applicability to the patient. 
         [0012]    One other object consists in the provision of a system of electrodes comprising low-cost elements, which disposal might not constitute an excessive burden to hinder the use thereof. 
         [0013]    One further objective consists in the provision of a system that might dispense the use of conductive pads for uniform distribution of the current at the area of contact with the skin of the patient. 
       BRIEF SUMMARY 
       [0014]    The objects set forth above, as well as others, are achieved by the invention by means of the provision of a system of electrodes formed of an assembly of electrode parts mechanically and electrically associated to the distal ends of the cables that conduct electrical signals to an equipment provided for the application of electrical stimuli or for the detection of electrical signals, such component parts being provided with an electrically conductive portion, and a low-cost portion comprising a support in the form of a flexible and porous blade, having applied to both faces thereof conductive portions formed by layers of electrically conductive materials, such layers being provided in electrical contact with one another, a first conductive portion, applied to the first side of the flexible and porous blade placed in contact with the electrode parts and a second conductive portion, applied to the second side of the blade placed in contact with the skin of the patient, the removable attachment of the electrode parts to the low-cost portion being provided by a first layer of adhesive material juxtaposed to the first side of the blade, and the removable attachment of the low-cost portion to the skin of the patient being provided by a second layer of adhesive material juxtaposed to the second face of the blade. 
         [0015]    According to another characteristic of the invention, at least one of the layers of adhesive material forms portions that surround the conductive portions. 
         [0016]    According to another characteristic of the invention, the electrically conductive material of at least one of the layers is simultaneously an adhesive material and a conductive material. 
         [0017]    According to another characteristic of the invention, the blade is provided with means for positioning the electrode parts. 
         [0018]    According to another characteristic of the invention, the positioning means are provided with visual indicators. 
         [0019]    According to another characteristic of the invention, the positioning means are provided by mechanical means. 
         [0020]    According to another characteristic of the invention, the positioning means are applied to the first side of the blade. 
         [0021]    According to another characteristic of the invention, the low-cost portion comprises a support that consists of a strap or strip of flexible fabric (textile) material, having affixed onto at least one of the faces thereof a flexible strip, which the latter comprises a flexible and porous supporting blade coated on both faces thereof with layers of conductive and adhesive materials. 
         [0022]    According to another characteristic of the invention, the flexible strip, comprising the layers of conductive and adhesive materials, is juxtaposed by means of adhesion of the first layer of adhesive material to the inner face of a strap of electrically insulating fabric/textile material. 
         [0023]    According to another characteristic of the invention, the means for positioning the electrode parts are comprised by cutouts or openings in the strap of fabric/textile material through which the electrode parts are removably attached to the first layer of adhesive material of the strip. 
         [0024]    According to another characteristic of the invention, the dimensions of the cutouts are slightly larger than those of the conductive parts of the electrode parts. 
         [0025]    According to another characteristic of the invention, the means used for positioning the electrode parts comprise protuberant elements provided in correspondence with the outer side of the strap. 
         [0026]    According to another characteristic of the invention, the means used for positioning the electrode parts comprise a template. 
         [0027]    According to another characteristic of the invention, the simultaneously adhesive and conductive portions are constituted by at least one layer of solid gel. 
         [0028]    According to another characteristic of the invention, the flexible strip consists in a continuous strip. 
         [0029]    According to another characteristic of the invention, the flexible strip is interrupted between the cutouts, the dimensions of the pieces of the conductive strip being sufficient to occlude the cutouts in the strap. 
         [0030]    According to another characteristic of the invention, the electrical contact between the upper layers of conductive materials is provided by means of pores provided in the supporting blade of the strip. 
         [0031]    According to another characteristic of the invention, the layers of electrically conductive materials and adhesive materials are applied directly over the fabric/textile material strap. 
         [0032]    According to another characteristic of the invention, the electrical contact between the layers of conductive materials is provided by means of pores provided in the fabric/textile material strap. 
         [0033]    According to another characteristic of the invention, the materials of the layers comprise a solid gel that is simultaneously conductive and adhesive. 
         [0034]    According to another characteristic of the invention, at least one of the solid gel layers is applied in a selective manner. 
         [0035]    According to another characteristic of the invention, the areas of mechanical fastening and electrical contact of the electrode parts are provided by the first solid conductive and adhesive gel layer applied selectively on the outer side of the strap. 
         [0036]    According to another characteristic of the invention, the means for electrical contact and removable mechanical attachment to the skin of the patient are provided by the second layer of solid conductive and adhesive gel applied selectively on the inner side of the strap. 
         [0037]    According to another characteristic of the invention, both layers of solid gel are selectively applied in the form of portions with defined dimensions and spacing distances, each of the portions on the outer side, forming the area of mechanical fastening and electrical contact of the electrode parts, in substantial alignment with the portion applied on the inner side of the strap. 
         [0038]    According to another characteristic of the invention, the electrode parts are secured, in a semi-permanent manner, to the first layer by means of juxtaposition and slight pressure. 
         [0039]    According to another characteristic of the invention, the electrode parts comprise, individually, a conductive portion in the form of a conductive blade and a physical and electrical connection thereof with an electrical signal conduction cable, the conductive portion having a shape and size compatible with the openings through which there is provided the contact of the conductive portion with the first conductive layer. 
         [0040]    According to another characteristic of the invention, the strap is provided with means for positioning the electrode parts. 
         [0041]    According to another characteristic of the invention, the positioning means comprise the openings provided in the strap. 
         [0042]    According to another characteristic of the invention, the positioning means are provided by a slab of low density flexible insulating material, such as rubber foam or synthetic resin, applied on the outer side of the strap, provided with openings that are coincident with the areas intended for mechanical fastening and electrical contact of the electrode parts. According to another characteristic of the invention, the slab is substantially continuous. 
         [0043]    According to another characteristic of the invention, the slab is segmented, being comprised of segments distanced from one another in the longitudinal and transversal directions of the strap 
         [0044]    According to another characteristic of the invention, the strap is provided, along the longitudinal borders thereof, of flaps that are superimposed by folding on the region of the strap wherein are provided the electrodes, providing a measure of protection thereto as well as to the cables associated therewith. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0045]    Further characteristics and advantages of the present invention will be better understood by means of the description of exemplary and non-limitative embodiments thereof, and of the figures to which such embodiments refer, wherein: 
           [0046]      FIGS. 1 and 2  depict an electrode strap (belt) structured in accordance with the prior art, as described in Patent Application No. BR PI 0704408, filed by the same applicant of the instant application. 
           [0047]      FIG. 3  shows a first embodiment of the inventive concept, using a flexible supporting strip, having applied on both sides thereof portions of conductive and adhesive materials. 
           [0048]      FIG. 4  shows a second embodiment of the inventive concept, wherein the adhesive material is applied in the form of a continuous layer. 
           [0049]      FIG. 5  shows, by means of a perspective view of an inner side, which remains in contact with a patient, a strap structured in accordance with the principles of the present invention. 
           [0050]      FIG. 6  shows, by means of a perspective view, a strip coated on both sides with materials that are simultaneously conductive and adhesive, which may be used together with the strap of the exemplary embodiment of  FIG. 5 . 
           [0051]      FIG. 7  shows a perspective view of the outer face of the strap shown in  FIG. 5 , structured in accordance with the principles of the present invention. 
           [0052]      FIG. 8  shows, by means of a perspective view, an electrode part used in connection with the present invention. 
           [0053]      FIGS. 9 - a  through  9 - d  show by means of cross-sectional schematic views, the various stages of the sequence of application of the strap to the patient. 
           [0054]      FIG. 10  depicts the folding of the outer flaps of protection of the electrode parts and respective cables. 
           [0055]      FIGS. 11 - a  and  11 - b  depict an additional embodiment of the invention. 
           [0056]      FIGS. 12 - a  and  12 - b  show a variation of the additional embodiment depicted in the preceding figures. 
           [0057]      FIG. 13  shows an implementation of the mechanical positioning means of the electrode parts on the strap according to the present invention. 
           [0058]      FIG. 14  illustrates an additional form of implementation of the means for positioning the electrode parts on the strap according to the present invention. 
           [0059]      FIG. 15  illustrates another form of an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0060]      FIG. 3  shows a first embodiment  30  of the invention, comprising a flexible strip  15 , preferably made of fabric/textile material, coated with conductive parts with defined size and spacing on portions  19  and  19 ′, respectively applied on the first side  15   a  and on the second side  15   b  thereof, the electrical contact between the conductive portions being provided by means of the material of the flexible strip  15 , either by means of the porous texture thereof, or by means of pores opened by known means, such as by mechanical perforation (not illustrated in the figure). According to the principles of the invention the conductive materials of portions  19  and  19 ′ comprise solid gels. As shown in the figure, the portions  19  and  19 ′ are substantially aligned with one another, that is, they occupy substantially coincident positions on the opposite sides of the flexible strip  15 . Surrounding the portions  19  and  19 ′, there are provided regions  18  and  18 ′ of adhesive material, respectively applied on the first and second sides  15   a,    15   b  of the flexible strip  15 . This material, which may consist in a solid gel, provides the retention of the electrode parts  17  on the surface of the flexible strip  15  and the contact of those parts with the conductive material of portion  19 , enabling the transmission to the latter of the electrical signals that travel along the connecting cables  17 ′. Due to the fact that the portions  19  and  19 ′ are in mutual electrical contact, and the latter is in contact with the skin of the patient, the arrangement shown in  FIG. 3  effectively provides the transmission of electrical signals between the skin of the patient (not illustrated) and the connecting cable  17 ′. According to what is shown in  FIG. 3 , the dimensions of contact area  16 , formed by the conductive portions  19 ,  19 ′ and adhesive regions  18 ,  18 ′, correspond substantially to the dimensions of the lower part (not visible in the figure) of the electrode part  17 , the lower part comprising an electrically conductive area. 
         [0061]      FIG. 4  illustrates a variation  40  of the arrangement shown in  FIG. 3 , differing therefrom in that an adhesive gel layer  20  is applied in a continuous manner, this gel providing the means for removable retention of the electrode parts (not shown) and physical contact thereof with conductive gel portions  21 . The accurate positioning of the electrode parts may be aided by the provisions of positioning means, which in  FIG. 4  are indicative signs  22  that are preferably printed on the surface of the flexible strip  15 . 
         [0062]    Notwithstanding that  FIGS. 3 and 4  exemplify strips, wherein are employed conductive materials distinct from the adhesive materials, there may be used, in the invention, materials that simultaneously exhibit adhesive properties and conductive properties, such materials being known and available in the form of solid gel. Furthermore, the composition of the gel that is applied to the first side of the flexible strip  15  may be the same or different from that which is applied to the second side, since the latter is supposed to establish the contact with the skin of the patient, while the other is intended to contact the electrode parts. 
         [0063]      FIG. 5  illustrates a non-restrictive exemplary embodiment  50  of the invention, whereto were added elements that complement the functionalities provided by the exemplary embodiments of  FIGS. 3 and 4 . The embodiment  50  comprises a strap of flexible non-conductive material  51 , which inner surface  51   a  is intended to be placed in contact with the skin when applied to the patient, with the opposite side  51   b  being provided facing outwards to allow the installation of the electrode parts. As illustrated in  FIG. 5 , the flexible strap  51  is provided with a plurality of cutouts with the shape of oblong openings spaced along a region that extends substantially along the center thereof. 
         [0064]    According to the principles of the invention and as illustrated in  FIG. 5 , a flexible strip  54  structured in accordance with the principles exemplified in the embodiments of  FIGS. 3 and 4  is glued on the region occupied by the openings, a width  55  thereof being sufficient to obstruct entirely the openings. In practice, the width  55  is slightly larger than dimension  56  of the openings in the transversal direction of the flexible strap  51 , in order to ensure the full occlusion thereof. The flexible strip  54  is permanently bound to the inner side  51   a  of the flexible strap  51 , and it should be noted that the raising of one of the ends  54 ′ thereof as illustrated in  FIG. 5  constitutes a mere graphical resource intended to enhance openings  52  and render the same more visible to the viewer hereof. 
         [0065]      FIG. 6  illustrates the flexible strip  54 , by means of a view in perspective wherein the vertical dimension—the thickness—is considerably enlarged in order to evidence the elements that compose the same. As may be observed, the flexible strip  54  comprises a central element or supporting blade  54   c  intercalated between a first layer of adhesive and conductive gel  54   a  and a second layer of adhesive and conductive gel  54   b.  The central element  54   c  may be constituted by a screen which mesh size is substantially open, in order to allow, through the openings therethrough, the contact and mutual adhesion between the first and second adhesive and conductive gel layers  54   a,    54   b,  that are electrically conductive, wherein there may be used a non-woven screen in a preferred embodiment of the invention. The characteristics of the adhesive and conductive gel layers  54   a,    54   b  may be the same or may be mutually distinct, in light of their different functions. The adhesive and conductive gel layer  54   a,  which stays adhered to the flexible strap  51  ( FIG. 5 ), should further allow the adhesion and removal of the electrode parts, as will be seen in the following. On the other hand, the adhesive and conductive gel layer  54   b  ( FIG. 5 ) should allow the attachment and removal of the flexible strap  51  to/from the skin of the patient, and should thereby exhibit characteristics compatible therewith, without causing irritation or allergic reactions. 
         [0066]      FIG. 7  shows the same flexible strap  51 , observed on its outer side, which side will stay exposed upon the application thereof to the patient. As may be seen in the  FIG. 7 , in this position the openings  52  allow selective access to the contact areas  57  of the conductive and adhesive and conductive gel layer  54   a  of the flexible strip  54  ( FIGS. 5 and 6 ), such cutouts  52  serving as means for positioning and spacing the electrode parts  58 . For the assembly of the latter it will suffice to remove the protective film  49  and juxtapose, applying thereby a slight pressure, the electrode parts  58  against the contact areas  57 . 
         [0067]    Still in accordance with  FIG. 7 , in a preferred embodiment of the invention, there are provided, parallel to a longitudinal axis  41  of the flexible strap  51 , flaps  69 ,  71 ,  73  and  75  intended to protect, by folding, the electrode parts  58  and respective cable assemblies  68  upon the assembly thereof on the flexible strap  51 . The flaps  69 ,  71 ,  73 ,  75  may be provided with retention means upon the folding, such as adhesive bands along the outer borders thereof or VELCRO®-type or equivalent closure means. However, these flaps  69 ,  71 ,  73 ,  75  may not be present in other embodiments. 
         [0068]    According to the detail shown in  FIG. 8 , each electrode part comprises on the lower side thereof a conductive portion  59 , which may comprise a metal plate—for example, made of copper, stainless steel, or an equivalent metal—or made of a conductive plastic material. Internally to the body of the part, preferably made of an insulating plastic, there is provided the union, preferably by welding  63 , of an end of a cable  62  for carrying electrical signals between the patient and the monitoring equipment, for example, an EIT apparatus. As illustrated in the figure, the dimensions of the opening  52  are provided to accommodate, with a minimal spacing gap, the conductive portions  59  of the electrode parts  58 . 
         [0069]      FIGS. 9 - a  through  9 - d  illustrate a preferred method of application of the flexible strap  51  to the patient, by means of a sequence of simplified sectional views corresponding to a cross-sectional plane  41  indicated in  FIG. 7 . The initial condition of the embodiment  50  is shown in  FIG. 9 - a,  wherein there may be observed that the conductive and adhesive gel sides  54   a,    54   b  of the flexible strip  54  are protected by disposable films: the protective film  64  protects the conductive and adhesive gel side  54   b  oriented towards the patient and the protective film  49  protects the conductive and adhesive gel side  54   a  oriented towards the flexible strap  51  and accessible from the outside through the openings  52  (not referenced in this figure). 
         [0070]    The first step of the application method, illustrated in  FIG. 9 - b,  consists in the removal of the protective film  49 , represented by the arrow  67 , thereby exposing the conductive and adhesive gel side  54   a  that forms the areas of contact with the electrode parts  58  (these areas of contact are referred with the numeral  57  in  FIG. 7 ), in addition to becoming adhered to the inner side  51   a  of the flexible strap  51 . To each of these exposed contact areas there is juxtaposed an electrode part  58 , which adhesion is provided by the simple compression of the conductive side  59  against the surface of the conductive and adhesive gel  54   a,    54   b.    
         [0071]    Subsequently, the electrode parts  58  and their respective cables are protected by folding over the same side flaps of the strap, if such flaps are present, as illustrated in  FIG. 10 .  FIG. 10  illustrates the strap upon the first flap  69  ( FIG. 5 ) having been folded to the position  69 ′, becoming superimposed over the electrode parts  58 , there being noted that cable assemblies  68 , each of the same corresponding to a set of four electrode parts  58 , extend to the outside through the cutouts  72 ′. After this first folding, the flap  71  is folded in the direction indicated by the arrow  71   a,  becoming superimposed over the already folded flap  69 ′. Subsequently, the cable assemblies  68  are deviated as indicated by arrows  68   a,  in order to be juxtaposed to the border  69   b  of the folded flap  69 ′, and are brought together forming a set of cable assemblies  68 , which protuberates through the cutout present between the flaps  73  and  74 . Finally, these last flaps  73 ,  74  are folded, as indicated by the arrows  69   a  and  74   a.    
         [0072]    Subsequently, an assembly formed by a strap carrying electrodes is applied to a patient. To that end, the protective film  64  of the conductive and adhesive and conductive gel layer  54   b  is removed, as indicated by the arrow  66  in  FIG. 9 - c.  The assembly is then pressed against the skin of a patient  65 , as illustrated in  FIG. 9 - d,  whereby the retention thereof is provided by the adhesive and conductive gel layer  54   b,  which also intermediates the carrying of the electrical signals. In  FIG. 9 - d  the protective flap  69 ′ is superimposed over the electrode part  58 . For better clarity of the figure, the remaining protective flaps have been omitted in the drawing. 
         [0073]    As illustrated in  FIG. 5 , the flexible strip  54  is provided in the form of a single piece, without interruptions between the adjacent openings  52 . Notwithstanding the fact that the continuity of the flexible strip  54  provides a resistive path between the adjacent electrode parts in contact with the skin of the patient, the effect of such continuity is negligible, and does not substantially influence the electrical behavior of the assembly. Thus, for example, considering the typical values of 4 cm 2  of a contact area  57  ( FIG. 7 ) for each electrode, a distance of 1.5 cm between the borders of adjacent electrodes, a thickness of 0.3 mm for the conductive gel layer and a gel resistivity p=1000 ohm-cm, there are obtained as a result the approximate values of from 10 to 20 kΩ between adjacent electrodes, while the resistance between the electrode part and the skin of the patient is of the order of only 5 to 10Ω. 
         [0074]    However, the inventive concept disclosed herein also includes an assembly in which the flexible strip  54  is segmented, that is, having interruptions between adjacent electrodes, with the segments having dimensions that are slightly larger, both in length and in width, than the openings  52 , in order to fully occlude the latter. 
         [0075]    In an additional embodiment  50 ′ of the disclosed concept, the flexible strip  54  is not used, and the adhesive and conductive gel layers  54   a  and  54   b  are deposited directly on the opposite sides of the flexible strap  51 . A first variant of that embodiment is shown in  FIGS. 11 - a  and  11 - b,  of which the first shows a part of a strap  51 ′ seen in its inner side  51 ′ a,  that is, which will be in contact with the patient, and the second is a cross-sectional view with the vertical dimension having been enlarged. As illustrated, in this embodiment there have been omitted the cutouts or openings  52  of the preceding embodiment  50 . In the areas  74  corresponding to the positions of the electrodes there are practiced a plurality of small through-openings or pores that provide communication between the outer side  51 ′ b  and the inner side  51 ′ a  of the strap  51 ′. Such openings  52  may be obtained by mechanical means or by any other known means of perforation, and this communication may further be provided by the web, itself, of the strap  51 ′, provided that the same is sufficiently porous. 
         [0076]    Upon the provision of the porous areas  74 , there are applied on opposite sides the conductive gel layers, to wit, the internal layer, which is continuous, of the gel  54 ′ b  on the inner side  51 ′ a  of the strap  51 ′ and the outer layer of the gel  54 ′ a,  which is segmented, on the outer side  51 ′ b  of the strap  51 ′, such gels being equivalent to the adhesive and conductive gel layers  54   b  and  54   a,  respectively, of the embodiment illustrated in  FIGS. 5 and 6 . This application may be provided using any known process, such as by spraying, silk-screen printing, offset printing, etc., provided that there is maintained the alignment between the areas coated with adhesive and conductive gel and the porous areas  74 , whose pores enable the physical and electrical contact between the inner and outer layers. 
         [0077]    In  FIGS. 12 - a  and  12 - b  there is illustrated a constructive variation of the preceding embodiment  50 ″, which differs from this latter only in regard of the inner layer of adhesive and conductive gel, which is deposited in segments  54 ″ b,  using the already cited application processes. It should be noted that, in this case, there should exist an alignment between the internal gel portions  54 ′ b,  the external gel portions  54 ′ a  and the areas  74 , that is, these elements should be provided substantially coincident with one another. In a preferred embodiment of the invention, the dimensions of the segments  54 ″ b  and portions  54 ′ a  are substantially coincident with those of the conductive portions  59  of the electrode parts  58 . 
         [0078]    As mentioned in connection with  FIGS. 5 and 7 , the means for positioning the electrode parts  58  may be provided by the openings  52 , as indicated in those figures. However, there may be used other positioning means, such as printed insignia, elements in relief glued on the outer surface of the strap  51 ′, or equivalent elements. In  FIG. 13  there is illustrated the use of a slab of soft elastic material  75 , such as rubber foam, a plastic material or an equivalent material, extending along the region occupied by the electrode parts  58 . This slab  75  is provided with openings or windows forming holes or frames  76  having dimensions compatible with those of the contact areas  57  that remain exposed at the bottom of the holes  76 , over which are applied the electrode parts  58 . 
         [0079]    In order to provide an enhanced flexibility to the assembly, the positioning slab  75  described in connection with  FIG. 13  may be segmented, as indicated in  FIG. 14 . In this figure, positioning elements  77  are mutually distanced both in the lengthwise direction and across the width of strap  80 . This transversal distancing allows the use of a protective film  78 , which covers the exposed contact areas  57  during the storage of the strap  80 , and is removed at the time of use thereof. 
         [0080]    Although the invention has been described with reference to specific exemplary embodiments, it should be understood that there may be introduced modifications therein by technicians skilled in the art, without deviation from the scope of the basic inventive concept thereof. 
         [0081]    In an additional form of an embodiment of the invention, the electrode parts are positioned separately with relation to the strap  51 , by means of use of an auxiliary template, not illustrated in the figures, whereon these electrode parts are mounted. After this mounting, the template carrying the electrode parts is applied to the flexible strap  51 , the parts then remaining attached by adhesion to the strap  51 , which is subsequently applied to the patient. Optionally, the strap  51  will not be used, and the template with the electrode parts  58  may be applied directly on the flexible strip  54  having been previously applied on the skin of the patient, in which case the protection of the electrode parts  58  and their respective cables may be provided by the template itself, or eventually by a protective band (not illustrated) placed externally. In another alternative form of an embodiment of the invention, the template is constituted by the flexible strap  51  per se without the flexible strip  54 . This embodiment is shown in  FIG. 15 , wherein the border of each opening  52  is coated, on the outer side  51   b  of the flexible strap  51 , by adhesive strips  79 . The assembly of the electrode parts  58 ′ shall be provided by superimposing the borders thereof onto the adhesive strips  79 , as indicated in  FIG. 15 , and it should be noted that in this case at least one of dimensions  81  of the electrode part  58 ′ shall correspond to the sum of the dimension of the opening  52  and the width of the adhesive strips  79 . Upon mounting the electrode parts  58 ′, according to the illustration of  FIG. 15 , the flaps are folded as described in connection with  FIG. 10 . At the time of use, the flexible strip  54  is applied to the skin of the patient, thereupon superimposing over this flexible strip  54 , the assembly formed by the strap  51  carrying the electrode parts  58 ′. 
         [0082]    Therefore, the present invention is defined and delimited by the set of claims that follow.