Abstract:
The ECG leadwire connector is designed in a way that allows low cost high volume manufacturing of an ECG leadwire assembly using standard continuous web converting processes and materials. The integrated ECG leadwire connector is assembled using the same printing and laminating processes that are used to construct the rest of the leadwire assembly. Patient safety requirements are met by the physical dimensions of the connector electrical contacts and by the thickness of a dielectric isolation feature which prevents inadvertent contact with potentially hazardous potentials, while still allowing the connector pins to make contact with the leadwire conductors. The connector also incorporates and RFID tag that allows multiple leadwire configurations to be accommodated and identified and authenticated during use.

Description:
FIELD 
       [0001]    The present application is directed to the field of ECG leadwire connectors. More specifically, the present application is directed to the field of disposable ECG leadwire applications and connectors. 
       BACKGROUND 
       [0002]    Previous disposable leadwire connectors did not adequately address the patient safety or radio frequency identification (RFID) features incorporated into the design of the present application. Accordingly, current leadwire connectors cannot be made to be disposable and compatible with the manufacturing processes used to construct leadwires on flexible printed substrate materials. 
         [0003]    Section 4.2.1 of the Association for the Advancement of Medical Instrumentation (AAMI) EC53 standard refers to the DIN 42-802 standard for ECG leadwire connector requirements to mitigate the potential hazard of a patient connected leadwire inadvertently making electrical contact with the power mains or other hazardous voltage sources. The DIN 42-802 standard specifies that a standard test probe such as a finger not be able to make electrical contact with the ECG leadwire connector pins (or sockets) when applied with a force of 30 N (6.744 lbs.). Section 8.5.2.3 of the AAMI ES60601-1 2005 C1 2009 has similar requirements except the test probe force is reduced to 10 N (2.248 lbs.). In addition the ES60601-1 standard requires 1.0 mm (0.039 in.) creepage distance, 0.5 mm (0.0196 in.) of air clearance, and a dielectric strength of 1,500 Vac for at least 1 minute, protection from mains voltage. 
         [0004]    Defibrillation patient safety requirements of AAMI EC11:1991/(R)2001 (section 3.2.14.2.2) dictate that the reduction in energy delivered to a patient being defibrillated be less than 10% of the total energy delivered by the defibrillator while an electrocardiograph and its associated leadwires are attached to the patient in order to maintain the efficacy of defibrillation. The defibrillator generates voltages of up to 5000V peak, therefore, in order to prevent “arcing” of defib energy shunting around the patient, the leadwires and the connector must maintain adequate electrical isolation (i.e., withstand 5000V peak). In order to guarantee this level of isolation a 8.0 mm (0.314 in.) creepage distance, 4.0 mm (0.157 in.) of air clearance must be maintained in order to support a dielectric breakdown strength of 5,000 volts between the exposed conductive surfaces of the connector. These dimensional requirements are based upon the assumptions of a pollution degree 2 level, using materials with a comparative tracking index (CTI) greater than 175 for the substrate, at an altitude less than 2000 meters above sea level. The non-exposed conductor areas of the connector/leadwire must also be constructed to support the 5,000 volt withstand level by incorporating appropriate conductor spacing&#39;s based upon the specific dielectric materials inbetween them. 
       SUMMARY 
       [0005]    In one aspect of the present application, an electrocardiograph (ECG) leadwire connector includes a plurality of electrode contacts, a plurality of connector pins corresponding to, and electrically coupled with each of the plurality of electrode contacts, wherein the plurality of connector pins and the plurality of electrode contacts are covered by a flexible dielectric substrate, the flexible dielectric substrate forming the ECG leadwire connecter, a stiffener area formed over the plurality of electrode contacts and affixed to the flexible dielectric material, a plurality of apertures on a first side of the stiffener area and the flexible dielectric substrate wherein the plurality of apertures expose a first side of each of the plurality of electrode contacts, and a plurality of alignment slots configured through the stiffener area and the flexible dielectric material, wherein the plurality of alignments slots define a separation between each of the plurality of electrode contacts. 
         [0006]    In another aspect of the present application, an electrocardiograph (ECG) leadwire system includes a ECG leadwire connector fashioned from a flexible dielectric substrate having a plurality of electrode contacts and a plurality of connector pins corresponding to, and electrically coupled with each of the plurality of electrode contacts, wherein the plurality of connector pins and the plurality of electrode contacts are covered by the flexible dielectric substrate, a stiffener area affixed to the flexible dielectric material wherein a first side of each of the plurality of electrode contacts are exposed, and a plurality of alignment slots configured to define a separation between each of the plurality of electrode contacts, and a mating connector configured to engage the ECG leadwire connector, wherein the mating connector includes a plurality of alignment tabs and a plurality of mating connector pins, wherein the plurality of alignment tabs engages the plurality of alignment slots of the ECG leadwire connector such that the plurality of electrode contacts maintain an electrical connection with the plurality of mating connector pins. 
         [0007]    In another aspect of the present application, an electrocardiograph (ECG) leadwire connector, comprising a plurality of electrode contacts, a plurality of connector pins corresponding to, and electrically coupled with each of the plurality of electrode contacts, a flexible dielectric substrate covering the plurality of connector pins and the plurality of electrode contacts, the flexible dielectric substrate forming the ECG leadwire connecter, a stiffener area formed over the plurality of electrode contacts and affixed to the flexible dielectric material, wherein the stiffener material has a minimum thickness of 0.040 inches, and a plurality of apertures on a first side of the stiffener area and the flexible dielectric substrate wherein the plurality of apertures expose a first side of each of the plurality of electrode contacts, wherein the plurality of aperture have a maximum width of 0.084 inches. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0008]      FIG. 1   a - 1   e  are graphical representations illustrating test probe calculations in accordance with an embodiment of the present application. 
           [0009]      FIG. 2  is a graphical representation illustrating an embodiment of the present application. 
           [0010]      FIG. 3  is a graphical representation illustrating an embodiment of the present application. 
           [0011]      FIG. 4  is a graphical representation illustrating an embodiment of the present application. 
           [0012]      FIG. 5  is a graphical representation illustrating an embodiment of a mating connector of the present application. 
           [0013]      FIG. 6   a  is a graphical representation illustrating an embodiment of a mating connector of the present application. 
           [0014]      FIG. 6   b  is a graphical representation illustrating an embodiment of a mating connector of the present application. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    In the present description, certain terms have been used for brevity, clearness and understanding. No unnecessary limitations are to be applied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes only and are intended to be broadly construed. The different systems and methods described herein may be used alone or in combination with other systems and methods. Various equivalents, alternatives and modifications are possible within the scope of the appended claims. Each limitation in the appended claims is intended to invoke interpretation under 35 U.S.C. §112, sixth paragraph, only if the terms “means for” or “step for” are explicitly recited in the respective limitation. 
         [0016]    Referring first to  FIG. 2 , an embodiment includes an ECG leadwire connector  10  design targeted for low cost disposable ECG leadwire applications. This connector  10  implements all of the required patient safety features in a construction that is compatible with the printing and laminating processes used to manufacture disposable ECG leadwires. In addition the connector  10  accommodates multiple leadwire configurations, which are identified by the electrocardiograph (not shown) reading the RFID tag  26  incorporated into the leadwire connector. For example, the RFID tag  26  will be able to identify for the ECG monitor whether the leadwire includes a single lead, a standard 12-lead, or perhaps a 5-lead ECG, or any other ECG leadwire set known in the art. The RFID tag  26  feature is also used to record leadwire usage information and to authenticate the leadwire types being used with the electrocardiograph device. In one embodiment, the RFID tag  26  is fashioned from the flexible printed substrate used to fashion the connector  10  and the ECG leadwires. An RFID chip may then be affixed to the substrate in one embodiment, or readymade RFID tags  26  may be affixed to the leadwire system in the connector  10 . Such an RFID tag  26  may be rewritable so that a user knows how long and how many times the particular connector  10  and/or leadwire set has been used. RFID tags are also compatible with the manufacturing process. 
         [0017]    Referring now to  FIGS. 2-6   b , an embodiment includes a disposable ECG leadwire assembly  8  having multiple conductive leadwire traces  19  printed on a flexible dielectric substrate  21 . Each conductive trace  19  is protected and isolated from contacting electrical potentials that could be potentially hazardous to the patient along its entire trace  19  length, except at each end. At one end, the conductive trace  19  is connected to an electrode  15  which is intended to be placed at specific locations on the body of the patient where the physiological ECG signal is to be measured. At the electrode contact  16 , the conductive trace  19  is exposed to allow an electrical connection to be established, by making contact with a mating connector pin  36  that is part of the mating connector  34 . In order to prevent hazardous potentials from inadvertently making contact with the electrode contact  16 , a flexible dielectric substrate  21  of prescribed thickness is permanently attached over the ECG leadwire connector  10  of the leadwire assembly  8 . This dielectric substrate  18 ,  21  has small apertures called alignment slots  12 ,  14  over the areas where the electrode contacts  16  are intended to make contact with the exposed portion of the mating connector pin  36 . In addition to these openings, the dielectric substrate  18  material also has narrow slot openings in between the contact access openings in order to introduce an “air gap” between the exposed portion of the connector pins  20 . The length of the air gap lot allows the spacing between the exposed portion of the connector pins  20  to be reduced to dimensions that are less than the required “creepage” distance between contacts. Creepage distance is the shortest distance between conductors along any surface. The spacing of the connector pins  20  is then only limited by the required “clearance” distance between contacts. Clearance distance is the shortest distance between conductors not restricted to a path on a material surface. By choosing the proper dielectric substrate  18  thickness, aperture, and slot dimensions, all of the required patient safety requirements can be met when the leadwire connector  10  is either connected to an electrocardiograph or in disconnected states. 
         [0018]    These requirements include a specified air “clearance” distance, “creepage” distance, and prevention of contact with the electrode contact  16  when using the “test finger” apparatus specified by the safety regulations on an unmated connector  10 . The leadwire connector  10  incorporates an RFID tag  26 , which does not require a conductive electrical connection to the electrocardiograph in order for information to be read from or written to the leadwire tag  26 . This allows the tag  26  to be embedded into the leadwire connector without impacting the safety or requiring additional leadwire connector pins. The leadwire connector  10  design supports attachment to the electrocardiograph device from several directions, i.e., front or back, and even allows multiple leadwire types to be connected simultaneously in order to perform different types of measurements. However, the connector  10  is configured such that the leadwire assembly  8  may only be connected to an ECG device, and not some other device having a more standard connection point, e.g., network plug, USB. This further reduces the instance of the leadwire assembly  8  being plugged into a dangerous voltage potential that could be hazardous to the patient. It should be further noted that the alignment holes  30 , that may be specifically fashioned for a particular ECG device, in other words, as shown in  FIG. 2  where there is only one alignment hole  30 , are configured such that the connector  10  contacts the correct position in the ECG device such that the alignment slots  12 ,  14  fit into the ECG device properly, and pin inside the receiver of the ECG device (not shown) receive the alignment hole  30 . 
         [0019]    Referring now to  FIG. 2 , an embodiment of the ECG leadwire connector  10  also includes the dielectric coating  18  fashioned around the alignment slots  12 ,  14 , as well as the electrode contact  16  and connector pins  20 . The alignment slots  12 ,  14  provide a contact separation  28  according to the discussion above, and further set forth below. The dielectric coating  18  also provides a trace separation  22  as will further be discussed. The stiffener area  24  allows for an additional material to be fashioned around the dielectric coating  18  such that the connector  10  is rigid enough to be plugged into an ECG device. It should be further noted that there are two different alignment slots  12 ,  14  wherein one type of slot  12  is longer than the shorter slot  14 . The type of slots  12 ,  14  utilized between any given set of electrode contact  16  may be configured according to the means of the connector  10 . 
         [0020]    Referring once again to  FIGS. 3 and 4 , an embodiment of the leadwire assembly  8  also will include an ECG assembly alignment hole  17  in the form of an aperture cut into the flexible dialectric substrate  21  such that the anatomy of the patient may be properly aligned with the ECG assembly alignment hole  17 . For example, the ECG assembly alignment hole  17  may be fashioned to be placed on the sternum of a patient with the narrow end of the ECG assembly alignment hole  17  pointing toward the head of the patient. 
         [0021]    Referring to  FIG. 5 , an embodiment of a mating connector  34  is illustrated. This mating connector  34  in an embodiment is installed in the ECG monitoring device (not shown), and receives the ECG leadwire connector  10 . The mating connector  34  includes alignment tabs  38  that receive the alignment slots  12 ,  14  of the ECG leadwire connector  10 , allowing the electrode contact  16  to maintain an electrical connection with the mating connector pins  36 . These pins  36  may then be electrically connected to the appropriate leads of the ECG monitoring device. 
         [0022]    Referring to  FIGS. 6   a  and  6   b , a further embodiment of the mating connector  34  is illustrated. Once again, this mating connector  34  includes a number of alignment tabs  38  for receiving alignment slots  12 ,  14  and mating connector pins  36 . In  FIG. 6   b , the mating connector  34  is inverted in order to illustrate the configuration of the mating connector pins  36 . 
         [0023]    Referring now to  FIGS. 1   a - e , these graphical representations illustrate test probe calculations according an embodiment. The tip of the test probe  32  has two radiuses as shown in  FIGS. 1   a  and  1   b . In  FIG. 1   a , the radius R4 is 4.0 mm+/−0.05 mm, and in  FIG. 1   b , the radius R2 is 2.0 mm+/−0.05 mm. The larger of the two radii R4 would prevent the test probe  32  from completely entering an opening that is larger than 2.0 mm but smaller than 4.0 mm.  FIGS. 1   c  and  1   d  illustrate cross-section IC and ID of  FIG. 1   b . To simplify the worst case analysis below, only the smaller radii R2 is considered. If the requirements are met under this simplified analysis, inclusion of the effects of the larger radii R4 will only improve the margin by which they are met. 
         [0000]    
       
         
               
               
               
             
           
               
                   
               
             
             
               
                 Smallest probe tip radius = 
                 1.95 mm 
                 0.077 in 
               
               
                   
               
             
          
         
       
     
         [0024]    Referring to  FIGS. 1   a - 1   e  and  FIG. 2  simultaneously, the leadwire connector  10  dimensions with respect to making electrical contact with the contacts  16  below the stiffener area  24  is the thickness of the stiffener material, which is 0.045 in+/−0.005 in, and the width of electrode contact  16  opening, which is 0.0785 in+/−0.005 in. Of course, further embodiments could be designed such that the opening size is based on the stiffener thickness to inhibit the finger probe from getting closer than a prediscribed distance from a protected conductive surface. 
         [0000]    
       
         
               
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 minimum stiffener thickness = 
                 0.040 in 
                  1.016 mm 
               
               
                   
                 maximum contact opening = 
                 0.084 in 
                 2.1209 mm 
               
               
                   
                   
               
             
          
         
       
     
         [0025]      FIG. 1   c  represents the geometry of the penetration distance d of the test probe  32  tip with radius R, into the stiffener opening slot width w, as calculated using the following equations (1)-(3): 
         [0000]    
       
         
           
             
               
                 
                   X 
                   = 
                   
                     
                       
                         R 
                         2 
                       
                       - 
                       
                         
                           w 
                           2 
                         
                         4 
                       
                     
                   
                 
               
               
                 
                   ( 
                   1 
                   ) 
                 
               
             
             
               
                 
                   d 
                   = 
                   
                     R 
                     - 
                     X 
                   
                 
               
               
                 
                   ( 
                   2 
                   ) 
                 
               
             
             
               
                 
                   d 
                   = 
                   
                     R 
                     - 
                     
                       
                         
                           R 
                           2 
                         
                         - 
                         
                           
                             w 
                             2 
                           
                           4 
                         
                       
                     
                   
                 
               
               
                 
                   ( 
                   3 
                   ) 
                 
               
             
           
         
       
     
         [0000]    where d represents the penetration depth of the test probe  32  into the connector  10 . The air clearance distance would be approximately the stiffener thickness minus the penetration depth and the creepage distance would be at least that much and likely be equal to the stiffener thickness itself. 
         [0026]    Therefore, the ECG leadwire connector  10  worst case test probe  32  penetration depth and air clearance distance is: 
         [0000]    
       
         
               
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 d = 
                 0.012 in 
                 0.314 mm 
               
               
                   
                 worst case air clearance = 
                 0.028 in 
                 0.702 mm 
               
               
                   
                 creepage distance 
                 0.040 in 
                 1.016 mm 
               
               
                   
                   
               
             
          
         
       
     
         [0027]    Based on this analysis, the test probe  32  tip cannot make contact with the electrode contact  16  within the connector  10 , and the worst case creepage distance is greater than the minimum 1.0 mm specified by the standards, excluding stiffener material compression affects. This analysis covers the 1,500 volt standards requirements which are intended to protect the patient from hazards associated with inadvertent contact with power mains or other hazardous potentials. A secondary aspect of the design which attains the 5,000V isolation associated with the maximum of 10% reduction in energy delivered by a defibrillator is accounted for by the 2 times the stiffener thickness plus the spacing between the contacts (i.e., air clearance, 4.0 mm minimum), and 2 times the stiffener thickness plus the surface distance around the ends of the air gap slots (i.e. creepage, 8.0 mm minimum). 
         [0028]    The connector  10  stiffener area  24  is made from a semi-rigid material which could have some deformation when subjected to a 30 N (6.744 lbs.) force, so the impact of this test probe  32  force on the creepage and air clearance distances may not be negligible. Materials for the stiffener area  24  may be selected from any appropriate materials which do not deform substantially under the indicated test finger probe pressure. 
         [0029]    This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.