Patent Publication Number: US-2019167976-A1

Title: Conductive human interface with polymeric electrical contact element

Description:
TECHNICAL FIELD 
     This technology relates to an electrically conductive human interface for communicating signals between an assistive device and the skin of a user. 
     BACKGROUND 
     An assistive device may function as a supplement to the body of a user. Examples include prosthetic devices, orthotic devices, exoskeletal devices, wheelchairs, and the like. Such an assistive device cooperates with the neuromuscular and skeletal systems of the user to operate under input from the user and/or to provide feedback to the user. This requires the communication of electrical signals such as, for example, transcutaneous electrical nerve stimulation (TENS) signals and electromyographic (EMG) signals, between the user and the assistive device. An electrically conductive human interface is thus provided to cooperate with the assistive device by conducting the electrical signals at the skin of the user. 
     SUMMARY 
     An apparatus is provided for conducting electrical signals at the skin of a user. In a given embodiment, the apparatus includes a fabric layer, an electrically insulating coating, and an electrical contact element. The fabric layer has an interior surface and an exterior surface. The coating has an exterior surface overlying the interior surface of the fabric layer, and has an interior surface exposed for contact with the skin of the user. The contact element includes a body of polymeric material with an electrically conductive additive dispersed in the polymeric material. The body of polymeric material reaches through the fabric layer and the coating, has an interior electrical contact surface exposed at the interior surface of the coating, and further has an exterior electrical contact surface exposed at the exterior surface of the fabric layer. 
     In another embodiment, the apparatus includes a plurality of electrical contact elements, each of which comprises a body of polymeric material with an electrically conductive additive dispersed in the polymeric material. Each body of polymeric material reaches through the fabric layer and the coating, has an interior electrical contact surface exposed at the interior surface of the coating, with an exterior electrical contact surface exposed at the exterior surface of the fabric layer. The apparatus further includes a separate component including an electrode. The separate component, which can be prosthetic socket, is configured to interconnect the electrode with an assistive device that is operable in electrical communication with the electrode. The separate component is further configured to be placed over the exterior surface of the fabric layer in a predetermined operative position relative to the fabric layer. The electrode is configured to contact one or more of the exterior electrical contact surfaces on the contact elements when the separate component is in the predetermined operative position. 
     An electrically insulating support structure may be included to support the contact elements in a fixed array separately from the fabric layer and the coating. The support structure can be received between the fabric layer and the coating, embedded fully within the coating, or mounted on the exterior surface of the fabric layer. The support structure may alternatively be configured to be donned as a band encircling a residual limb, or as sleeve with an open proximal end and a closed distal end. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front sectional view of a prosthetic liner equipped with electrical contact elements. 
         FIG. 2  is an enlarged view of parts shown in  FIG. 1 . 
         FIG. 3  is a front view, partly in section, of a socket for use with the liner of  FIG. 1 . 
         FIG. 4-10  are sectional view similar to  FIG. 2 , each of which shows a respective alternative embodiment of an electrical contact element. 
         FIG. 11  is a perspective view of a support structure with electrical contact elements mounted on the support structure. 
         FIG. 12  is a sectional view of parts shown in  FIG. 11 . 
         FIG. 13  is a view similar to  FIG. 12 , showing an additional part of an apparatus that includes the support structure of  FIG. 11 . 
         FIGS. 14 and 15  are views similar to  FIG. 12 , showing parts in alternative arrangements. 
         FIG. 16  is a perspective view of an electrode device. 
         FIG. 17  is a side view of the electrode device of  FIG. 16 . 
         FIG. 18  is a perspective view of an alternative support structure for electrical contact elements. 
         FIG. 19  is a front view of an alternative support structure for electrical contact elements. 
         FIG. 20  is a view similar to  FIG. 1  showing an alternative embodiment of the apparatus. 
         FIG. 21  is an enlarged view of parts shown in  FIG. 20 . 
     
    
    
     DETAILED DESCRIPTION 
     The embodiments illustrated in the drawings have parts that are examples of the elements recited in the claims. The illustrated embodiments thus include examples of how a person of ordinary skill in the art can make and use the claimed invention. They are described here to meet the enablement and best mode requirements of the patent statute without imposing limitations that are not recited in the claims. One or more of the elements of one embodiment may be used in combination with, or as a substitute for, one or more elements of another as needed for any particular implementation of the claimed invention. 
     The apparatus  100  shown in  FIG. 1  includes a liner  120  for a prosthetic socket. The liner is receivable over a user&#39;s residual limb. The apparatus  100  further includes electrical contact elements  122  mounted on the liner  120 . The contact elements  122  are configured to communicate electrical signals with the skin of the user at the residual limb and, together with the liner  120 , to provide an interface between the user and an assistive device (not shown). The assistive device can be any device that cooperates with the neuromuscular and skeletal system of the user. Such devices include, for example, prosthetic devices, orthotic devices, exoskeletal devices, powered wheelchairs, and the like. While the example of  FIG. 1  relates to a prosthetic liner  120 , the apparatus  100  can alternatively include a sleeve, a band, a pad, or any other suitable device configured for contact with the skin of the user. In each case, any suitable number of the contact elements  122  can be provided as needed for communicating the assistive device with the appropriate neuromuscular structure of the user. 
     The liner  120  has a generally conical shape with a longitudinal central axis  131 , an open proximal end  132  through which the residual limb projects into the liner  120 , and a closed distal end  134 . In the illustrated example, the liner  120  includes a fabric layer  140  and a soft coating  142 . The fabric layer  140  has an interior surface  144  covered by the soft coating  142 . The fabric layer  140  further has an exterior surface  146  which, as shown in  FIG. 1 , is exposed as the outermost surface of the liner  120 . The soft coating  142  has an exterior surface  150  overlying the interior surface  144  of the fabric layer  140 . The soft coating  142  further has an interior surface  152  exposed for overlying contact with the user&#39;s skin at the residual limb. 
     The fabric layer  140  is configured to form a flexible substrate. Suitable materials include, for example, stretch controlling fabrics, stretchable non-woven materials, fiber-on-end fabrics, and the like. A stretch-controlling fabric can be more stretchable in one direction than another direction. For example, a stretch-controlling fabric can have a limited stretch direction that is substantially orthogonal to a non-limited stretch direction. In the example shown in  FIG. 1 , the stretch-controlling fabric is oriented to permit greater stretch in a radial or circumferential direction than in an axial or other longitudinal direction. 
     The soft coating  142  is provided for comfortable long term wear. As shown in  FIG. 2 , the soft coating  142  is an electrically insulating body of elastomeric material. As used herein, the term “insulating” means that the material can be classified as an electrical insulator, i.e., a material having sufficiently high resistivity to substantially prevent current flow when exposed to operating voltages of the device. The elastomeric material may comprise a soft polymer such as, for example, thermoplastic elastomers (TPE), silicones, block copolymers, urethanes, or the like. 
     Each contact element  122  preferably has the configuration of the contact element  122  shown for example in  FIG. 2 . Each contact element  122  thus has a peripheral side surface  160  reaching fully between first and second opposite end surfaces  162  and  164 . The contact element  122  reaches through the fabric layer  140  and the soft coating  142  such that the first end surface  162  is exposed at the interior surface  152  of the soft coating  142  and the second end surface  164  is exposed at the exterior surface  146  of the fabric layer  140 . The contact element  120  may protrude slightly beyond the interior and exterior surfaces  152  and  146 , with the first and second end surfaces  162  and  164  raised slightly from those surfaces  152  and  146 , as shown. In this arrangement the first end surface  162  serves as an interior electrical contact surface exposed for contact with the skin of the user to receive EMG signals produced by muscles of the user, or to transmit TENS or other electrical signals to the skin of the user. The second end surface  164  serves as an exterior electrical contact surface exposed for contact with an electrode at a separate component, such as a socket in which the liner  120  is received, as described below. 
     As shown schematically in  FIG. 2 , each contact element  122  is formed as a body of polymeric material  170  in which an electrically conductive additive is dispersed to impart electrical conductivity. The polymeric material can include TPE, silicones, block copolymers, urethanes, or the like, and may have any one or more of the specific compositions and properties disclosed in copending U.S. patent application Ser. No. 15/726,624, filed Oct. 6, 2017, which is incorporated by reference in its entirety. For example, the polymeric material  170  may comprise a medical grade silicone such as Dragon Skin® 30 silicone by Smooth-On, Inc. of Macungie, Pa., USA. 
     The electrically conductive additive may comprise conductive particles and/or strands of materials such as, for example, gold, copper, nickel, iron, iron-oxide, silver, carbon, carbon black, carbon nanotubes, graphite, or combinations thereof, and may also may have any one or more of the specific compositions, concentrations, configurations and properties disclosed in the above-noted U.S. patent application Ser. No. 15/726,624 which is incorporated reference. Accordingly, the electrically conductive additive can be provided in the form of conductive particles  172  as shown schematically in  FIG. 2 . 
     A socket  200  for use with the liner  120  is shown schematically in  FIG. 3 . Like the liner  120 , the socket  200  has a generally conical shape with a longitudinal central axis  201 , a proximal end  204 , and a distal end  206 . The proximal end  204  is open for receiving the liner  120  with the residual limb. The distal end  206  is closed by an electrical connector  210  with a processing device  212  (shown schematically). 
     An interior surface  220  of the socket  200  is configured for overlying contact with the exterior surface  146  of the liner  120  when the liner  120  is located within the socket  200 . Electrodes  230 , which are preferably formed of metal, are mounted on the interior surface  220  of the socket  200 . The electrodes  230  are provided to make electrical signal-transmitting contact with the contact elements  122  on the liner  120 . Specifically, each electrode  230  is configured and arranged to adjoin the exterior electrical contact surface  164  on one or more of the contact elements  122  when the liner  120  is located in a predetermined operative position in the socket  200 . Conductive signal lines  232  communicate the electrodes  230  with the processing device  212  at the connector  210 . The contact elements  122  on the liner  120  are thereby connected in signal-transmitting communication with the processing device  212  at the connector  210  when the liner  120  is in the predetermined operative position. 
     The connector  210  is configured to electrically communicate the processing device  212  with the assistive device. The processing device  212  is configured to transform EMG signals at the contact elements  122  into control signals for the assistive device. Additionally or alternatively, the processing device  212  is configured to transmit electrical signals to the contact elements  122  for TENS, to create information flowing into the body, or to provide feedback from the assistive device. 
     In the embodiment shown in  FIG. 2 , the peripheral side surface  160  of the contact element  120  is cylindrical with a uniform diameter between planar opposite end surfaces  162  and  164 . Alternative embodiments are shown in  FIGS. 4-10 . 
     In the alternative of  FIG. 4 , a contact element  300  has an interior electrical contact surface  303  with a dome-shaped contour. In  FIG. 5 , a contact element  310  has a dome-shaped contour at both the interior and exterior electrical contact surface  312  and  314 . In  FIG. 6 , a contact element  320  has a planar interior electrical contact surface  322  on an inner end portion  324  that protrudes from, and projects over, the interior surface  326  of the corresponding soft coating  328 . In  FIG. 7 , a contact element  330  has planar interior and exterior electrical contact surfaces  332  and  334  on protruding opposite end portions  336  and  338  that project over the interior surface  340  of the soft coating  342  and the exterior surface  344  of the liner  346 , respectively. The embodiment of  FIG. 8  differs from that of  FIG. 7  where an interior electrical contact surface  350  has a dome-shaped contour. The embodiment of  FIG. 9  differs from that of  FIG. 7  where a length section  360  between the opposite end portions  362  and  364  is tapered radially inward from the opposite end portions  362  and  364 . The embodiment of  FIG. 10  has a similarly tapered hourglass configuration between opposite end portions  370  and  372  of an entirely cornerless contact element  374 . In each embodiment, the contact element fits closely through the soft coating with the non-conducting material of the contact element adjoining, and is preferably bonded to, the surrounding non-conducting material of the soft coating. 
     As shown in  FIGS. 11 and 12 , a support structure  400  also can be provided. The support structure  400  supports a plurality of contact elements  402 , each of which is configured as described above. Specifically, the support structure  400  supports the contact elements  402  in a fixed array that is predetermined with reference to multiple electrodes. The array includes distinct groups of contact elements  402  that are arranged for each electrode to make signal-transmitting contact with only one respective group of contact elements  402  without making signal-transmitting contact with any contact element  402  in any other group. 
     In the illustrated embodiment, the support structure  400  is shaped as a sheet with a uniform thickness between planar opposite side surfaces  412  and  414 . The sheet  400  is formed of electrically non-conductive material such as silicone. As shown in enlarged detail  FIG. 12 , the contact elements  402  are received closely through apertures  415  in the sheet  410  such that the electrical contact surfaces  420  and  422  are equally spaced inward and outward from the corresponding side surfaces  412  and  414 . The contact elements  402  can be press-fitted into the apertures  15 , but are preferably bonded to the surrounding material of the sheet  400 . 
     The sheet  400  can be used to support the contact elements  402  in a conductive human interface as described above. For example, the sheet  400  can be installed in a liner like the liner  120  of  FIGS. 1 and 2 . As shown in  FIG. 13 , the sheet  400  is installed as a layer between the fabric layer  140  and the soft coating  142 . One side surface  414  of the sheet  400  overlies the interior surface  144  of the fabric layer  140 . The exterior surface of  150  of the soft coating  144  overlies the opposite side surface  412  of the sheet  400 . As shown in  FIG. 14 , the sheet  400  can be embedded within the soft coating  142 . As shown in  FIG. 15 , the sheet  400  can be mounted on the exterior surface  146  of the fabric layer  140 . 
     An electrode  500  device for use with the support structure  400  is shown in  FIGS. 16 and 17 . The electrode device  500  includes a body  502  of electrically insulating material, with inserts  504 ,  506  and  508  formed of electrically conductive material such as titanium. The inserts  504 ,  506  and  508  serve as distinct electrodes with planar electrical contact surfaces  510 ,  512 , and  514 , respectively. The contact surfaces  510 ,  512 , and  514  are sized, shaped, and spaced apart from the each other to make signal-transmitting contact with a respective group of the contact elements  402  shown in  FIG. 11 , and to do so without making signal-transmitting contact with any contact element  402  in common with another of the contact surfaces  510 ,  512  or  514 . Grooves  519  ( FIG. 17 ) at opposite ends of the body  502  are provided to secure the electrode device  500  in an installed position embedded in a wall of a socket  520 , with the contact surfaces  510 ,  512  and  514  exposed at the interior surface  522  of the socket  520 , as described above with reference to the embodiment of  FIG. 3 . 
     Another embodiment of a support structure  600  is shown in  FIG. 18 . This support structure  600  is configured as an electrically insulating sheet  604  with multiple arrays  610  and  612  of apertures  615  for receiving electrical contact elements like the contact elements  402  of  FIG. 11 . However, the sheet  604  of  FIG. 18  is continuous circumferentially about an axis  617 . The sheet  604  is thus configured to be donned as a band encircling a residual limb. The arrays  610  and  612  of apertures  615  are located on the sheet  604  at circumferentially spaced-apart locations that are predetermined with reference to the neuromuscular structure of the residual limb. 
     In the additional embodiment of  FIG. 19 , a support structure  700  also is configured to be donned over a residual limb. This embodiment of a support structure  700  has a shape similar to that of the liner  120  of  FIG. 1  or the socket  200  of  FIG. 3 . Accordingly, the support structure  700  has a longitudinal axis  701 , an open proximal end  702 , and a closed distal end  704 . Multiple arrays  710  and  712  of apertures  715  are provided receiving electrical contact elements like the contact elements  402  of  FIG. 11 . The arrays  710  and  712  of apertures  715  have circumferentially spaced-apart locations that are predetermined with reference to the neuromuscular structure of the residual limb. 
     The additional embodiment of  FIGS. 20 and 21  includes an electrically insulating body of elastomeric material  800 . Like the soft coating  142  of  FIGS. 1 and 2 , the body  800  has a generally conical shape with a longitudinal axis  801 , a closed distal end  802 , and an open proximal end  804  for receiving a residual limb. The body  800  also has an interior surface  808  exposed for overlying contact with the user&#39;s skin at the residual limb. However, unlike the soft coating  142 , the body  800  is not covered by a fabric layer. Instead, the body  800  in this embodiment is intended for the socket  200  of  FIG. 3  to be received directly over the exterior surface  810  of the body  800  without the use of an intervening fabric layer. 
     As further shown in  FIGS. 20 and 21 , the body  800  serves as a support structure for electrical contact elements such as, for example, the contact elements  122  described above. Each contact element  122  reaches through the body  800  such that the interior electrical contact surface  162  is exposed at the interior surface  808  of the body  800 , and the exterior electrical contact surface  164  is exposed at the exterior surface  810  of the body  800 . The interior electrical contact surfaces  162  are thus exposed for overlying contact with the skin of the user at the residual limb. The exterior electrical contact surfaces  164  are thus exposed for contact with the electrodes  230  in the socket  200 . 
     This written description sets for the best mode of carrying out the invention, and describes the invention so as to enable a person of ordinary skill in the art to make and use the invention, by presenting examples of the elements recited in the claims. The detailed descriptions of those elements do not impose limitations that are not recited in the claims, either literally or under the doctrine of equivalents.