HK40032200A - System for electrical stimulation of nerves - Google Patents

Description

System for electrical nerve stimulation

Technical Field

The present invention relates generally to electrical stimulation of nerves. More particularly, the present invention relates to neuromodulation (neuromodulation) therapies, including treatment of pelvic floor disorders, such as urinary or fecal voiding dysfunction. Neuromodulation therapy utilizes electrodes in combination with a pulse generator that includes a predetermined program that is adjustable by a caregiver and/or a user.

Background

Medical studies have shown the beneficial effects of electrical stimulation of the dorsal genital nerve in the treatment of urinary and fecal incontinence (incontinence). The dorsal genital nerve is composed purely of afferent/sensory fibers and therefore there are no unwanted motor functions activated by electrical stimulation of those nerves.

Incontinence diseases may afflict individuals of various ages, sexes, and races, and may be associated with disease, injury, and/or aging. Electrical neuromodulation has been shown to be effective in eliminating or substantially reducing the severity of symptoms of such dysfunctions, such as urinary or fecal incontinence.

The dorsal genital nerve is located on the dorsal superficial surface at about 1/4 in the upper part of the penile cross-section and extends along the length of the shaft of the penis until reaching the glans and then fanning out at the glans.

In women, the dorsal genital nerve tends to be near the mucosa (or skin) near the pedicles between the labia minora and labia majora.

Thus, these stimulation sites are effective for both men and women, as factors such as loss of adipose layers and muscle tissue have a significant positive impact on the activation of the target nerve. At the intended stimulation site, the adipose layer is limited and there is no muscle covering the nerves [ DOI: 10.2298/JAC0802035K electric for transient simulation, 2008 ].

The target nerve for a particular product is The Dorsal genital nerve (clitoral/penile nerve), which may be approached with surface electrodes using a suitable stimulation setup [ H.B. Goldman et al, facial genetic nerve simulation for The treatment of The overview bladder systems, neurological and minor, Vol.27, No. 6, page 499 503, month 2008, J.word, &. Tt translation = L "&. G L &. lTt/T g G G.Fyne, S. L acoustic, K.K.Krogh and N.J.M.Rijkhoff, The facial nerve simulation for The treatment of The genital nerve, visual nerve simulation for The patient, page 25. 9. The facial nerve simulation for The treatment of The genital nerve, page 25, visual nerve simulation for The patient, No. 13, visual diagnosis of The facial nerve simulation for The patient, No. 13.

However, these sites are also very challenging for conventional surface electrodes because of the large tissue movement during daily activities and the complex geometry of the site to which the electrodes may have to be attached. In applications where continuous stimulation is critical to the success of the therapy provided, daily activity presents a further challenge to the maintenance of function of currently available surface electrodes in predetermined locations.

Surface or patch electrodes have been used for decades for electrical stimulation of neural tissue. Thus, currently available transdermal patch electrodes are considered standard conventional devices for surface stimulation and are often used for a variety of applications for almost the entire human body, including veterinary applications as well. The target area is the genital area, i.e. near the pubic symphysis and/or in close proximity to the clitoris or foreskin. They should be allowed to be applied on hairy skin, especially for female use. Shaving is known to cause skin irritation and itching in many instances, and thus may be uncomfortable for many users. The anode or return electrode may be located near or remote from the cathode or stimulating electrode. The latter case may provide the option of a relatively large electrode, thereby eliminating many of the fixation problems that the cathode electrode has to solve.

The patch electrodes are typically secured to the skin by using a conductive adhesive gel surface or by using an acrylic or rubber based adhesive support. This type of electrode is disclosed in U.S. patent No.4,066,078 to Berg. In most cases, such electrodes are used for planned event or session treatments (outpatient sessions) and, due to the risk of relaxation, require limited movement by the user, thus losing effectiveness. Other electrodes may be worn for days, for example, in applications such as event and Holter monitors (Holter monitors), or used as a means of patient screening programs.

Effective neuromodulation of the dorsal genital nerve relies on good contact with the target tissue. Good clinical results rely on constant electrical performance between the stimulation electrode and the target tissue. Accordingly, it is a general objective to design electrodes that include features that will prevent the electrode from moving, falling, or otherwise coming loose contact with the target tissue during daily use. Furthermore, the electrode design should allow for easy detachment. For hygienic reasons, the electrode concept should also address the need for a hygienically acceptable solution for both men and women. For this reason, disposable electrodes are preferred, but electrodes with limited life cycles are acceptable, and therefore high mechanical integrity is not a real issue.

The adhesive patches are often conveniently cut into individual shapes to meet certain requirements. However, most patch electrode designs make only a few attempts to accommodate the anatomical challenges of the target structure, and therefore they are mostly different in size to avoid feeling, skin burns and reduce hot spots, and are tailored to the injected charge.

For the inevitable case of physical activity, conventional patch electrodes require some additional support to remain fixed and function in the desired position. Such supports are commonly used to improve electrode fixation, including various devices such as adhesive tape or for brain sensing electrodes, helmet array fixation devices are well known and therefore are not an enhancement of the adhesive effect of the actual active stimulation surface as one of the main objects of the present invention.

Depending on the clinical support setting of a particular patient/user, application of the product of the invention may require either rapid initiation of stimulation (if requested/when requested) or continuous use during the day and/or night. Therefore, the reliability with which the electrodes are held in place and function is of greater importance for this product and may be a different use scenario than many other applications currently on the market. The importance of reliable and comfortable electrode fixation is even further highlighted in the important aspect of freedom of movement required during daily activities such as walking, cycling, running or other athletic activities. The requirement for rapid start-up presents challenges to docking the electrodes such that the electrodes cannot be calibrated or repositioned in time.

A suitable profile design is advantageous, but this is not considered critical. To avoid the risk of unacceptable skin/tissue burns, a well designed charging limit for the minimum active area is required. In addition, the problem of edge bites/punctures should be properly addressed. The support element should not cause excessive donning/doffing burden and should also not cause unacceptable pain and skin irritation from use (including removal). If these challenges are not addressed, the electrode will not be suitable for long term use.

US patent application US2015/0352357 to Medtronic represents a method of electrode fixation in which the stimulation system relies on good tissue contact through the underpants/shorts/underwear. For male users, electrodes formed as flexible rings are additionally provided for support. However, none of these designs specify or present any suitable means to meet the electrode fixation challenges previously described. There is a particular need for a solution for female users. The principles provided for male electrode ring support are a frequently used approach in many applications.

Conventional surface or patch electrodes have lead strands placed on a scrim or mesh fabric to evenly distribute the current to the gel member. The swage type snap connectors are typically located in a rigid polymer sheet material, directly interfacing with the underlying gel member, typically supported by another layer of rigid polymer based sheet material. Unfortunately, these components also constitute elements that add rigidity to the final electrode, which prevents the prior art electrodes from maintaining functional contact with tissue near the female back genital nerve.

Among the currently available electrodes, the processing methods share many similarities with pressure sensitive tape manufacturing, utilizing conversion techniques that include die cutting to form electrode patches. In addition to these methods, adhesive-based assembly techniques are used for wire attachment, or stamping a swaged connector or magnet into the patch portion of the electrode. Many electrodes provide a composite structure that includes a metal or other electrically conductive support member to which electrical leads from an associated pulse generator may be attached. The gel member of the prior art electrode is extruded as a layer or sheet. Layers with various properties can constitute the final gel member as described in EP1052933B1 by Axelgaard.

The prior art electrodes most often describe a design in which a continuous scrim fabric, polymer sheet and metal mesh is implemented and supports a flexible gel element. It is therefore an object of these inventions to provide suitable means for positioning and holding in place the gel member of a transcutaneous electrical stimulation electrode, while focusing on the flexibility and flexibility required for application of the electrode unit necessary on complex geometries, such as without regard to the woman's foreskin and labia minora. The final electrode unit should resemble the tissue to which it is applied. None of the currently available prior art electrodes exhibit the level of flexibility required to maintain function at the intended stimulation site.

Due to the poor strength and high notch sensitivity of conductive gels, a scrim layer is typically embedded on the gel member to enable handling and application of the gel member components to the surface of the conductive member. This limits the flexibility of prior art electrode designs. In conventional surface electrode designs, the back of the electrode unit is often composed of a fabric, typically made of spun-bonded polyolefin fibers. The scrim layer may also be located elsewhere in the laminate structure of the electrode. The non-flexible spunbond scrim layer secures the lead member to the electrode assembly and constitutes the primary structural element of the final electrode.

Therefore, there is an urgent need to provide a reliable means of securing electrodes to skin having anatomical structures and complex tissue geometries.

Disclosure of Invention

It is an object of embodiments of the present invention to provide a system which overcomes or at least reduces the above disadvantages.

With reference to the above advantages of the scrim layer and the effect of omitting the scrim layer, the gel member may stretch or deform during processing, but it must be understood that this is a desirable effect for the present invention and that the features of the gel member minimize internal stresses in the gel member.

The electrode unit of the invention, also defined herein as an "electrode", exhibits unparalleled flexibility and constitutes a design particularly suitable for application to tissues with complex geometries, such as the female foreskin, for targeting the dorsal genital nerve.

The present disclosure relates to the fixation of stimulation electrodes to anatomically challenging structures with geometrically complex curvatures, the electrodes having design features that allow the electrode unit to adapt to the surrounding tissue to which it is applied. The design includes a shaped housing member that constitutes a physical and structural framework for the conductive gel member of the electrode, specifically tailored to be soft and flexible while still being retractable from the skin. This is resolvable due to the nature of the housing member walls or the included details of the substrate member as part of the housing member or added to the housing member. When used with either type of connector, the combined structures and elements constitute active stimulation electrode unit designs of various shapes and sizes. The structural housing member is designed to adapt to the natural curvature of the skin, the purpose of which is to deliver transcutaneous electrical stimulation, and should therefore constitute a flexible element.

The shell-type gel fixation member should allow the application of a soft gel composition over the anatomy of the female genital perineum and male genitalia near the pubic symphysis, while preventing adhesion to any garment used. Ideally, the flexibility of the complete electrode unit should closely mimic the flexibility of the tissue to which it is applied. Although a softer and more flexible component does not constitute a functional problem, it may thus limit the lifetime of the electrode unit or even prevent reuse of the electrode unit.

In a first aspect of the invention, an electrode is provided, particularly adapted to provide suitable electrical contact and fixation to the skin of a patient in areas with irregular tissue structure, the electrode unit comprising a flexible non-conductive housing member forming the main structure, a flexible matrix member, a conductive member, a connection member comprising means for connection to an external pulse generator, a rubber-like gel member, wherein the flexible matrix member is arranged in the housing member and fixes the conductive member and supports the rubber-like gel member, the conductive member forming means for an electrical connection evenly distributed from the connection member to the gel member, and wherein the rubber-like gel member also provides mechanical fixation of the electrode unit to the skin of the patient.

In another embodiment, a second electrically conductive gel member is disposed between the housing member and the rubber-like gel member. This has the effect of enhancing the flexibility of the electrode unit.

Explained more specifically, an electrode suitable for stimulating the dorsal genital nerve according to the invention generally comprises a housing member acting as a base plate of an electrically conductive member, including means for providing an electrical connection with a pulse generator. In addition, the electrode comprises a substrate member on which is positioned or applied a conductive member, which is any suitable type of graphene or graphitized coating, silver-based coating or conductive sponge or conductive fabric mesh member. The above described element is filled with an electrically conductive gel member and a rubber-like gel member as means for providing an electrical interface to the skin of a patient, the gel member being adhered to an electrically conductive member added to a matrix member.

In an embodiment, the matrix member is provided with an electrically conductive member which is one or more of a graphene or graphitized coating, a silver-based coating or an electrically conductive sponge or an electrically conductive fabric mesh member.

In an embodiment, the housing member comprises natural rubber or synthetic rubber having a hardness less than or equal to shore a hardness 50.

In an embodiment, the natural rubber is latex.

In an embodiment, the elastomer is one or more of silicone, thermoplastic elastomer (TPE), or Thermoplastic Polyurethane (TPU).

In an embodiment of the electrode unit, the housing member, wherein the matrix member is arranged and constitutes the physical means of reinforcing the rubber-like gel member and holding the rubber-like gel member in its intended position, forms a protective element towards clothing or other parts of the body which are not intended to be stimulated, while providing means for connecting the members to form an electrical contact with the electrically conductive member. In this way, the base member functions as a base plate-like member.

In an embodiment, the matrix member comprises a plurality of protrusions and/or cavities, the protrusions forming pins and the cavities forming pockets, the pins and/or pockets having a first end and a second end, the first end interfacing with the housing member and the second end interfacing with the rubber-like gel element.

In an embodiment, the pins and/or dimples are distributed over a footage of the housing member and protrude from or are formed in the housing member in a straight or angled direction.

In an embodiment, the pin and/or the recess are an integral part of the housing member.

In an embodiment, a low friction coating is provided to at least a portion of the outer surface of the housing member.

In an embodiment, the electrode unit comprises a homogeneous gel member arranged and cured within the housing member and the matrix member, thereby replacing the rubbery gel member and the second electrically conductive gel member with one component to constitute the means for contacting both the electrically conductive member and the skin of the patient.

More particularly, the matrix member constitutes an element that limits the need for high peel strength of the applied amount of conductive gel member to make contact with the conductive member. Thus, the homogeneous rubber-like gel member constitutes a means for contact with both the conductive member and the patient's skin.

However, to increase the flexibility and softness of the gel member, a first volume of low or unplasticized (e.g., commercially available)AG2500 series or AG700 series) conductive gel compound is disposed into the housing member to form contact with the substrate member, and then plasticized with another more rigid (e.g., commercially available) conductive gel compoundAG500 series) conductive gel compound to cover the housing member to form an interface with the patient's skin, and vice versa. To adjust for different characteristics of the gel member of the first volume and the second volume, the first volume contains no or less glycerin or similar plasticizer than the second volume.

In an embodiment, the electrode unit comprises a first volume of a thixotropic non-plasticized gel member having a high viscosity and a second volume of a gel member plasticized to form a rubber-like structure, wherein they form an electrically conductive gel member providing an electrical connection to the skin of the patient.

In an embodiment, the connecting member has a plurality of conductive strands.

In yet another embodiment, the plurality of connecting strands are distributed in a fan-shaped manner and are located within the matrix member or within the shell member above the matrix member.

More specifically, to further assist in evenly distributing the current to the interface of the patient's skin, leads having a plurality of strands twisted at the ends are distributed in a fan-like manner within the matrix member prior to the addition of the conductive member. This also has the effect of evenly distributing the stiffness of the lead to form a uniform and very low flexural stiffness element. Thus, stiffening elements concentrated along the lead are avoided. Thus, the frequently observed consequences of poor and/or unreliable current densities provided by larger prior art electrodes are accommodated by means of a gel-supporting matrix member located in a housing member that provides a mechanical structure to the electrode unit without compromising the softness or flexibility of the electrode unit.

Since the elements of the electrode unit of the present invention are applied in order to reduce the overall stiffness of the electrode unit in any direction, for the necessary mechanical strength, a fixation structure for the lead or swaged snap connector or magnet connection is required, resulting in strain relief for the connector member strands. This is addressed by arranging the component to a limited extent to a position where the leads penetrate the wall of the housing component to make electrical contact with the conductive member located on the base member. An integrally molded portion of high durometer silicone is preferred because it has minimal impact on the overall stiffness of the electrode unit. Yet another suitable solution is to cut before applying the low friction coating to adjust the size of the scrim that is adhered to the outside of the electrode unit.

More specifically, in an embodiment of the electrode unit, the electrode unit comprises a non-conductive housing member, including means for structural support of the connector member in the form of molded details forming a limited degree of cavity or partially covered scrim layer.

In embodiments, where the first volume of gel member is non-plasticized, a thickener is added as one or more of an ethylene copolymer or gelatin.

In another embodiment, the matrix member is configured with a density of the matrix member that matches the viscosity of the first volume of gel member such that the two elements ensure electrical contact with the electrically conductive member and the first volume of gel member remains interlocked in the matrix member. In this way, the matrix member constitutes a soft elastic and flexible structure.

In one embodiment, the wall side of the housing member is designed with an excessive edge line length.

In another embodiment, the edge lines form a curtain-like serpentine shape, adding expansion spring features to the edge lines.

To increase the flexibility of the lips, they can be designed to have a curtain-like design, thereby reducing or eliminating the need for highly flexible materials. Wall heights of up to 10mm are feasible.

In an embodiment, the wall side height is less than or equal to 10 mm.

For the preferred solution, the overall design of the housing member is droplet shaped to provide the user with the option of individual positioning. However, the shape may be rectangular, square, circular and oval or any other shape, as the shape is not critical to the overall function of the electrode design, but rather should be adapted to the treatment and anatomical region to which it is applied. Thus, in an embodiment, the shape of the shell member is one of a droplet, a rectangle, a square, a circle, or an ellipse or a polygon.

This design increases the flexibility of the electrode unit, thereby minimizing the stress in the edge lines of the electrode unit and providing additional grip for the gel member to be further fixed in the housing member.

In another embodiment, the electrode unit further comprises a flexible matrix member that is one of a conductive open-cell sponge, a conductive fabric, or a conductive coated molded structure with a tailored density that forms an adhesive support for the second rubber-like gel member.

In embodiments where the matrix is designed to constitute pins and/or dimples of a particular density, the surface area and mass of the matrix member is configured to the viscosity and/or adhesive properties of the gel member. The pin and/or recess design in the matrix member should constitute a sufficient area while also enhancing the integrity of the gel member. It is important that the pin design be notch resistant. In embodiments, the matrix member has a pre-elongation-to-break at least similar to the pre-elongation-to-break of the gel member or a pre-elongation-to-break of at least 100% strain. The pin and/or dimple design should preferably have a length to diameter ratio greater than 2:1, otherwise additional dimples or cavities may be required. This means that for many applications the pin length or pit depth becomes greater than 2 mm. However, the length of the pin and the depth of the recess should be designed with respect to the overall depth of the part intended to be in abutment with the skin. Thus, a smaller footage can introduce a pin length and pit depth shorter than 2mm without compromising the internal structural strength and integrity of the electrode unit. It is foreseen that in such applications the pin length may be as short as 0.1mm and still provide sufficient grip in the electrode unit as a whole. However, the length of the pin and/or the dimple hole may be up to or as deep as 10 mm. Thus, in an embodiment, the pin length and/or the pit depth of the at least one pin or pit is in the range of 0.1mm to 10 mm.

Undercut holes provide additional gripping force and may replace the pin elements completely or partially, but require a certain wall thickness of the housing member. An elongated pin, which in an embodiment forms a matrix member, protrudes from the shell member. The orientation may be at a right angle to facilitate better reception of the conductive member by the interface. In an embodiment, at least a portion of the elongated pin protrudes from the housing member in an angled direction. This contributes to better gripping of the gel member and the rubber member, and better prevention of decomposition of the electrode unit. The pins, like the dimples, are undercut and need not be of regular shape. Thus, within the scope of the present invention, in embodiments, the pins and/or dimples have varying diameters and/or cross-sections over the length of the stroke.

A longer length or a greater ratio constitutes an advantage of both protecting the integrity of the gel member and providing additional adhesion to the housing member rather than to the patient's skin. However, other length to diameter ratios are acceptable when the lip design in the housing member properly supports the gripping features of the substrate member. In addition, the pin length in the base member design is also affected by density, meaning by the number of pins per square unit. Thus, in a high density matrix design, a lower pin design is also acceptable if properly tailored with the gel member employed. The density of the matrix need not be constant, but may in some designs advantageously have a higher density at the edge lines than at the center, because the edge lines are subjected to higher strain when the electrode units are removed from the skin. The curtain edge line design also adds a gripping force effect to the gel member by adding a surface in contact with the shell member to the gel member.

The matrix member also constitutes a means of enhancing the integration of the wire strands with the conductive member and with the shell member. The matrix member design additionally enhances the area and/or volume of the conductive member, thereby further reducing the risk of charge density hot spots.

The substrate member may be considered as a chassis member which integrates the elements constituting the electrode unit. In one embodiment, the substrate member is an integral part of the shell member. In embodiments, the matrix member is added to the housing member by means of a conductive open-cell sponge, fabric, scrim or mesh fabric.

It must be understood that the matrix members must not constitute a rigid element and therefore the matrix members should constitute a flexible material and/or a highly open structure, i.e. steel wool. In an embodiment, the substrate member comprises steel wool. For the sake of completeness, it should be appreciated that the term steel wool not only covers wool made of steel, but in a broad sense steel wool may also be made of iron, low-grade carbon steel wire, aluminium, bronze or stainless steel of different qualities. The metal is chopped into fine strands that resemble wool when formed into fuzzy clumps. Thus, for this embodiment, the characteristics of the matrix member and the characteristics of the gel member should match.

In an embodiment, the strands of the lead connector are distributed in a fan-like shape inside the housing member before coating with the conductive carbon/graphene-based material. In an embodiment, the electrode unit further comprises a snap or magnetic attraction connector or a magnetized connector arranged with the housing member. Even though the snap or magnetic connector represents a rigid element, it is mounted in or on the housing member in a thicker design. However, the underlying surface should have a surface finish that allows for sufficient adhesion to the applied gel member. In designs where the patient may connect the product to the electrode unit using a snap or magnetic connector before applying the electrodes to the intended stimulation site. The snap or magnetic connector also constitutes a means of the applicator to position the electrodes as desired.

The outer side of the electrode unit, i.e. the side pointing away from the target tissue, should have low friction surface properties in order not to stick to the underwear of the patient's choice. In a preferred design, this is achieved by spraying the silicone outer surface with a low friction silicone based addition cure coating, such as the commercially available NuSil MED 6670 or a suitably selected parylene coating.

Although the combination of gel fixation, housing member shape, dimensions and material, and gel composition all play a role in the flexibility of the final stimulation electrode unit, the cross-sectional profile determines some flexibility characteristics.

The lens or droplet shaped electrode unit may feature a gel composition that follows the internal shape to also constitute the lens shape, i.e. to have a pre-shaped form and thus to follow the specific tissue intended for stimulation. This is achieved by a process of filling the shell member and subsequently curing the gel member.

Typical patch lead designs are superior as a connecting member due to their flexible nature. However, since the electrodes themselves are designed to be highly flexible, typical swaged snap connectors or magnetic connectors can also be used, especially for thicker electrode designs, which are optional. Other connection elements such as magnets may be applied, especially when the magnetic connector is designed with a predominantly longitudinal shape at the principal bending line of the electrode.

Gel materials commonly used for patch electrodes for transdermal applications, such as low modulus rubbery gel formulations, may also be used in combination with the housing member. However, the gel compound material properties can be tailored to meet the overall flexibility level of the final electrode unit design.

In an embodiment, the electrode includes a gel member configured to be highly thixotropic and having a relatively high viscosity, and the case member is molded from a soft silicone resin having a matrix member of a matching density.

Gel compound materials having relatively high viscosities are designed and arranged in combination with a soft silicone molded housing member having a matching matrix member density, resulting in a highly flexible electrode unit design.

In an embodiment, the electrode unit comprises a gel member constituting a plurality of gel elements, thus increasing the flexibility of the final gel member itself. A series of combinations of fluid gel materials and rubbery gels plasticized with various levels of hardness form the final gel member. By carefully combining the viscosities of the gel elements, the final gel member can be made more flexible. A strong rubber-like gel element is used at the edges of the electrode unit, whereas the centrally located gel element is almost liquid in its behavior. A liquid gel is located at the bottom of the housing member with a cover of a rubber-like gel constituting the electrode/skin interface.

In an embodiment, the electrode unit comprises a low durometer prefabricated housing member coated with an electrically conductive member configured to evenly distribute electrical charge in the electrode unit and provide electrical connection to a connection member arranged with a flexible matrix member providing fixation of a first liquid-like gel element filled into the matrix member to a level where the matrix member provides mechanical support for a second rubber-like gel element converted from a sheet of pre-cured hydrogel, which forms a barrier to the liquid gel element and comes into contact with the patient's skin.

Although the invention has been described using a specific embodiment of a treatment system for urinary incontinence, it should be appreciated that the present application is not limited to such an application, but encompasses all applications of surface stimulation intended for neuromodulation, wherein the invention solves the following technical problem: that is, a device having technical features to facilitate electrical stimulation using electrodes that should be held in a desired position is provided.

Drawings

For the purpose of illustrating the invention, there are shown in the drawings forms that are presently preferred, it being understood, however, that the invention is not intended to be limited to the precise arrangements and instrumentalities shown.

Fig. 1 illustrates the side of the electrode unit to be applied to the skin of a patient. It includes a version of the matrix member details, a lip design to enhance the flexibility of the housing member, and leads to provide the stimulation signals to the electrodes. The electrode unit comprises a base member (1) with details shown as a pin design, a boundary lip design (2) providing the electrode unit with geometrically flexible edges, and it has a conductive electro-graphitic coating constituting a conductive member that distributes the electrical energy evenly to the skin. The signal is supplied by a pulse generator, not included in the figure, through a lead (3),

fig. 2 illustrates the electrode unit in the top surface pointing away from the patient. It comprises a low friction top coat member having a smooth surface texture (4) for limiting adhesion to any garment, and a lead-type connector distribution interface (5) for stimulation signals provided by a pulse generator,

figure 3 illustrates an electrode unit in which a gel member (6) is located inside the housing member, which in an embodiment creates a highly viscous lip design with overfill of the housing member, and extends below the housing member lip design (2),

fig. 4 illustrates the electrode unit in the top surface pointing away from the patient. In this embodiment, the housing member is designed to be shaped as a lens (7). The lens does not utilize an internal gel to hold the matrix member and therefore should be combined with a gel member having suitable plasticization and viscosity. A second gel member for increasing skin adherence may be applied,

fig. 5 illustrates a fan-shaped lead strand distribution (8) that disperses the interior of the lead strands in a matrix member located inside the housing member of the electrode unit. In addition, the lead connector securing element (9) is shown molded on top of the housing member of the electrode unit,

figure 6 illustrates an electrode unit featuring a swaged snap connector (10) in an embodiment,

fig. 7 illustrates the side of the electrode unit to be applied to the skin of a patient. It comprises another version (1) of the matrix member details in the housing member, a lip design for enhancing the flexibility of the housing member and providing additional gel member fixation, and a magnetic based contact element (13). The electrode unit comprises a base member (1 and 11) with details of the pin and recess/cavity design shown as combined, and a boundary lip design (2) providing the electrode unit with a geometrically flexible edge,

fig. 8 illustrates the exterior of the embodiment depicted in fig. 7, with the magnetic connector element (12) located at the center of the housing member, an

Figure 9 illustrates a detailed view of the curtain edge design (2), which may be a portion of any of the previously described figures. A curtain edge having a plurality of at least three curvatures forming irregular or regular overlength edge lines provides additional flexibility and further fixation of the gel member. The curtain elements do not necessarily have the same dimensions or are formed identically.

Detailed Description

For the purpose of illustrating the invention, there are shown in the drawings forms that are presently preferred, it being understood, however, that the invention is not intended to be limited to the precise arrangements shown.

Fig. 1 shows an embodiment of an electrode unit using classical lead connections (3). A commonly used snap connector is another means for connecting the lead to the pulse generator, as shown in fig. 6, and an additional magnetic connector is shown in fig. 8. Other electrical connectors are optional, such as a receptacle connector or any other type suitable for connection to a pulse generator device.

The geometric surface area of the electrode unit is at least 25mm²To prevent too large a charge density from eventually stimulating the tissue. The surface electrode unit of fig. 1 is shaped to assist the user in biasing towards various positioning options. The housing member of the electrode unit may be made of various polymers such as, for example, low durometer silicone, natural or synthetic rubber, latex, injection molded thermoplastic elastomers or rubber, or even polyurethane. It must be appreciated that the applied material should form a highly flexible housing member, and therefore other materials with similar properties should also be considered as an alternative and within the scope of the invention.

The attached lead-connected lead portion or connected lead should preferably be soft and flexible, and for embodiments utilizing a swaged snap connector or magnetic connector as shown in fig. 6 and 7, respectively, the thickness of the electrode unit should be large enough to allow the rigid portion of the connector element to be able to move or tilt relative to the skin to which the electrode unit is to be secured. In a preferred design, where the housing member is made of flexible silicone, the material portion into which the snap connector is secured is made of a more rigid type of silicone to enhance the strength of the assembly. Thus, the snap connector sized ring element is made of high hardness silicone, which is molded into the housing member. Another way of establishing a suitable mechanical connection is by means of gluing snap-in or magnetic connectors into the housing member by means of converted adhesive tape or fluid glue.

For embodiments utilizing a lead-type connection, the conductor portion of the lead should penetrate the outer housing member to reach into the gel member to establish an electrical connection with the patient's skin/tissue. A portion of the lead should be fixed to the outside of the case member as shown in fig. 5, wherein the bridging element fixes the lead to the outside of the case member.

The main parts of the electrode design are the housing member in which the gel material is arranged, and the connection member providing the stimulation signal. When the gel member should provide adhesion to the skin to be electrically stimulated, the outer surface of the shell member should be non-adhesive and non-adhesive. This may be achieved by applying a low friction top coat member and/or having a smooth surface structure to limit adhesion to any clothing or other parts of the body, which provides a means for reducing the risk of accidentally pushing down the electrode.

However, the main characteristic of the shell member is that, although it is highly flexible, it has a physical structure when molded, and thus supports the gel member which is poor in mechanical strength. The ultimate elongation before fracture of the shell member should be at least 25% in view of the flexibility requirements. However, the stress-strain characteristics of the shell member should be comparable to the stress-strain characteristics of the applied gel member and therefore the fracture should preferably be at least 100%. Above this level, there is a limit to improvement of the characteristics of the entire electrode unit, although there is an additional advantage.

In fig. 3, the overfill of the housing member is illustrated as an additional lip below the curtain edge detail. As shown in fig. 2, overfilling can also be established by filling the shell member to the edge line of the curtain design, and further on top of this, positioning the sheet of pre-cured gel as a cover. In this manner, more aqueous gel compound may be included as part of the gel member.

In thinner designs, or in designs of lens shape as shown in fig. 4, special surface treatment devices manipulate the physical or morphological properties of the inner surface of the shell member in such a way and to such an extent that an acceptable level of adhesion to the gel member is established, whereby these devices constitute the matrix member. The treatment should be balanced with the properties of the gel member, which should be designed with sufficient rubber characteristics. However, a key performance criterion is that the assembled electrode remains sufficiently flexible in any direction and therefore the gel member cannot be too stiff.

In fig. 5, a scalloped distribution of the conductive portions of the lead connector member is shown. This method of conductor distribution provides a means of uniformly distributing charge into the gel member and thus further provides an equal charge distribution throughout the active electrode area. Furthermore, the fan-shaped conductor distribution adds stability to the gel member and serves as a matrix element or reinforcement to the matrix member. If the conductive portions of the leads have a longer length, they may be crimped to form a mesh-like element that constitutes the matrix member. However, while it may be suitable for smaller electrode applications, this will not result in equally good charge distribution.

The scallops are created by spreading a plurality of uniformly distributed conductive leads over a substrate member and then manipulating the conductive strands into a substrate member. The gel member is cast on the matrix member, thereby soaking the conductive portion of the lead, and then cured. In this way, a flexible solid component constituting the electrode is formed.

The graphitized coating material or any other commonly used conductive material (e.g., silver-based coating) may be used alone or added to improve the uniform distribution of the stimulating current on the gel surface or to act as a conductive member alone. To further assist in the current distribution evenly across the electrode/skin interface, the connector member component having an interface of the conductive member in contact with the gel should be designed to have appropriate electrical characteristics. In embodiments utilizing magnetically enhanced connections, as shown in fig. 7, the properties of the gel should compensate for the less desirable current distribution directly below the magnet elements. Otherwise, the magnet element is either not part of the electrical connection, or it will be directly electrically insulated from the magnet itself, in order to avoid hot spots and thus concentrate the current distribution.

The surface area of the lip design of the housing member should be considered as an additional means for sufficient surface area, as well as means for further securing the gel member into the housing member. The combined surface area of the curtain lip design and the matrix member design, including all hydrophilic or grip enhancing features, together form a gel member that is bonded to the housing component and the matrix component, rather than to the patient's skin. As shown in fig. 9, the design method of the curtain edge details is practically unlimited and may therefore be regular or irregular, with sharp corners or rounded, but should constitute excessively long edge lines with respect to the projected surface area of the electrode in contact with the patient's skin.

In a preferred design, the housing member is obtained by liquid injection molding of a low-hardness silicone resin component or preforming using a low-hardness high-consistency silicone rubber. If a hardness such as 00 shore hardness 50 is used, a wall thickness of a maximum thickness of 1mm is acceptable for a limited wall height of about 5 mm.

If details are provided that further enhance the flexibility of the wall, such as curtain design, the wall height can be extended to about 10mm or even higher when the added gel compound provides sufficient flexibility. The bending stiffness of the entire electrode unit, including the gel compound and the lead member, should be kept low, thereby allowing the electrode unit to be maximally adapted to the structure to which it is intended to be applied.

When increasing the stiffness of the silicone material used for the housing member, then the dimensional thickness should be reduced and similarly the wall height ratio should be increased to maintain the overall flexibility of the overall electrode unit design. The higher the stiffness of the silicone material, the thinner the wall thickness is generally required, while combining the higher wall height and the bending properties of the included gel material(s).

More specifically, the internal structure of the shell member comprises a matrix member consisting of, for example, a distribution of pins or cavity elements, fibers or open-cell sponges. The purpose of the matrix member is to provide support for the rubber-like gel member, which is particularly important for utilizing thicker gel components with wall heights greater than 5 mm. In combination with the ultra-soft gel material, the design of the matrix member is more important, as the matrix member also provides a means for protecting the integrity of the gel member or its composite material. The matrix member supports the rubber-like gel member and allows the placement of the high viscosity, preferably thixotropic, gel member within the matrix member. The characteristics of the adhesive gel compound should be matched to the density of the design of the matrix member and, in addition, to the layer thickness of the gel member. If the gel member is nearly aqueous, the design of the matrix member should have a higher density than the design where the gel member is plasticized into a rubbery shape during the curing process. Examples of useful gel compounds are e.g. according to Axelgaard patent US7252792B2, which is commercially available. The composite structure of the layers of a particular formulation is advantageous since the water content may affect the viscosity of the gel compound. Thicker electrode designs can be achieved in softer electrode units using thixotropic electrolyte solutions, non-plasticized high viscosity gels or low plasticized gels suspended in the electrode matrix member and covering the material with a sheet of plasticized rubbery gel. Such a multi-component gel member design results in low internal stress of the gel member itself during use, thereby providing a high level of adaptability to tissue expectations. The properties of the skin layer rubber plasticizing gel compound should be of sufficient integrity to avoid decomposition and leaving a substantial amount of gel residue on the skin.

An important feature of the matrix member is to provide sufficient surface area for the gel member to adhere to the housing member when the electrode is detached from the skin. The details of the matrix member are designed to be hydrophilic to further enhance the grip on the gel member. When curing the gel member into a matrix member and only adding limited rigidity to the final electrode unit, the integrity of the gel member is supported by the design of the matrix member. Thus, the properties of the matrix member should allow a high degree of flexibility together with the gel member, so that the matrix member does not constitute a stiffness enhancing element.

In a properly designed conventional electrode, care is taken not to bring the conductive element into contact with the skin. Since the conductive member is typically composed of a metal mesh fabric, skin contact can result in charge concentrations or hot spots, which can cause irritation or even become unsafe. For the shell electrode cell design, this is a limited consideration because there is no rigid member and thus the hot spot is only relevant for dried out electrodes (which would be the case for any hydrogel-based electrode design). To limit any associated risks, the matrix member design should not cause any adverse reactions.

However, the matrix member is not intended to be brought into contact with the skin. In addition, this is to ensure the maximum possible surface area of the gel member with the skin. In designs where overfilling the shell member with gel material is part of the intended design, the height of the matrix member should be flush with the wall height to maximize the integrity of the softer gel component.

The matrix member is particularly useful for providing sufficient grip to retain the gel member within the shell member rather than adhering the gel member to the skin of the patient. This is accomplished by designing the matrix member to have sufficient surface area and to include the hydrophilicity of the matrix member for application of the conductive member. The characteristics of the conductive member should include good adhesion of the gel member. The surface area of the housing member lip design should be considered as an additional means for sufficient surface area. The combined surface area of the lip design and the matrix component design, including any hydrophilicity or grip enhancing features, together form a gel member that is bonded to the shell member and the matrix member, rather than to the patient's skin.

An overhead of 50% is considered sufficient, but more overhead is beneficial. If the overhead gripping force of the substrate member and the housing member with respect to the gripping force of the skin is too low, the possibility of the electrode unit disintegrating is considerable, and therefore the removal of the electrode is impaired, and detachment becomes unacceptable in everyday practice.

Claims (35)

1. An electrode particularly adapted to provide suitable electrical contact and fixation to the skin of a patient in an area having an irregular tissue structure, the electrode unit comprising:

-a flexible non-conductive housing member forming a body structure,

-a flexible matrix member,

-an electrically conductive member having a conductive layer,

a connecting member comprising means for connecting to an external pulse generator,

-a rubber-like gel member,

wherein the flexible matrix member is arranged in the housing member and fixes the electrically conductive member and supports the rubber-like gel member, the electrically conductive member forming means for evenly distributing the electrical connection from the connection member to the gel member, and wherein the rubber-like gel member also provides mechanical fixation of the electrode unit to the skin of the patient.

2. The electrode of claim 1, wherein a second electrically conductive gel member is disposed between the housing member and the rubber-like gel member.

3. The electrode of claim 1 or 2, wherein the matrix member is provided with an electrically conductive member which is one or more of a graphene or graphitized coating, a silver-based coating or a conductive sponge or a conductive fabric mesh member.

4. The electrode of any of claims 1-3, wherein the housing member comprises natural or synthetic rubber having a hardness less than or equal to 50 Shore A.

5. The electrode of claim 4, wherein the natural rubber is latex.

6. The electrode of claim 4, wherein the elastomer is one or more of silicone, thermoplastic elastomer (TPE), or Thermoplastic Polyurethane (TPU).

7. An electrode according to any one of claims 1 to 6, wherein the housing member, wherein the matrix member is arranged and constitutes a physical means of strengthening the rubber-like gel member and holding it in its intended position, forms a protective element towards clothing or other parts of the body not intended to be stimulated, while providing means for the connection member to form an electrical contact with the electrically conductive member.

8. The electrode of any one of claims 1 to 7, wherein the matrix member comprises a plurality of protrusions and/or cavities, the protrusions forming pins and the cavities forming pockets, the pins and/or pockets having a first end and a second end, the first end interfacing with the housing member and the second end interfacing with the rubbery gel member.

9. The electrode of claim 8, wherein the pins and/or dimples are distributed on the footage of the housing member and protrude from or are formed in the housing member in a straight or angled direction.

10. The electrode of any one of claims 8 or 9, wherein the pin and/or the recess are an integral part of the housing member.

11. An electrode as claimed in any one of claims 1 to 10, wherein a low friction coating is provided to at least a portion of the outer surface of the housing member.

12. The electrode of any one of claims 1 to 11, wherein the electrode unit comprises a uniform gel member disposed and cured within the housing member and the matrix member, thereby replacing the rubbery gel member and the second electrically conductive gel member with one component to constitute means for contact with both the electrically conductive member and the patient's skin.

13. The electrode of any one of claims 1 to 12, wherein the electrode unit comprises a first volume of a thixotropic non-plasticized gel member having a high viscosity and a second volume of a plasticized to form a rubber-like structure gel member, wherein they form an electrically conductive gel member that provides an electrical connection to the patient's skin.

14. The electrode of any one of claims 1 to 13, wherein the connecting member has a plurality of conductive strands.

15. The electrode of claim 14, wherein the plurality of connecting strands are distributed in a fan-shaped manner and are located within the matrix member or within the shell member above the matrix member.

16. An electrode as claimed in any one of claims 1 to 15, wherein the electrode comprises a non-conductive housing member, including means for structural support of the connector member in the form of moulded details forming a limited degree of cavity or partially covered scrim layer.

17. The electrode of any one of claims 1 to 16, wherein the gel member of the first volume is non-plasticized, and wherein a thickener is added as one or more of an ethylene copolymer or gelatin.

18. The electrode of any one of claims 1 to 17, wherein the matrix member is configured with a density of matrix member that matches the viscosity of the gel member of the first volume such that both elements ensure electrical contact with the electrically conductive member and the gel member of the first volume remains interlocked in the matrix member.

19. The electrode of any one of claims 1 to 18, wherein the wall side of the housing member is designed with an excess edge line length.

20. The electrode of claim 19, wherein the edge wire forms a curtain-like serpentine shape, adding expansion spring features to the edge wire.

21. The electrode of claim 19 or 20, wherein the wall side height is less than or equal to 10 mm.

22. The electrode of any one of claims 1 to 21, wherein the shape of the shell member is one of a droplet, a rectangle, a square, a circle, or an ellipse, or a polygon.

23. An electrode according to any one of claims 1 to 22, comprising a flexible matrix member that is one of a conductive open-cell sponge, a conductive fabric, or a conductive overmolded structure with a tailored density that forms an adhesive support for the second rubber-like gel member.

24. The electrode of any one of claims 1 to 23, wherein the matrix member is designed to constitute a specific density of pins and/or pits, and wherein the surface area and mass of the matrix member is configured to the viscosity and/or adhesion properties of the gel member.

25. The electrode of any one of claims 1 to 24, wherein the matrix member has a pre-elongation-to-break at least similar to the pre-elongation-to-break of the gel member or at least 100% strain.

26. The electrode of any one of claims 8 to 25, wherein the pin and/or pit design preferably has a length to diameter ratio of greater than 2: 1.

27. The electrode of any one of claims 8 to 26, wherein the pin length and/or pit depth of at least one pin or pit is in the range of 0.1mm to 10 mm.

28. The electrode of any one of claims 8 to 27, wherein the pins and/or dimples have varying diameters and/or cross-sections over the stroke length.

29. The electrode of any one of claims 1 to 28, wherein the matrix member is an integral part of the shell member.

30. The electrode of any one of claims 1 to 29, wherein the matrix member is added to the housing member by means of a conductive open-cell sponge, fabric, scrim or mesh fabric.

31. The electrode of any one of claims 1 to 30, wherein the matrix member comprises steel wool.

32. The electrode of any one of claims 1 to 30, wherein the strands of the lead connector are distributed in a fan-like shape inside the housing member prior to coating with the conductive carbon/graphene-based material.

33. The electrode of any one of claims 1 to 32, wherein the electrode comprises a snap or magnetically attractive or magnetized connector arranged with the housing member.

34. The electrode of any one of claims 1 to 33, wherein the electrode comprises a gel member configured to be highly thixotropic and having a relatively high viscosity, and the shell member is molded from a soft silicone with a matrix member of matching density.

35. An electrode according to any one of claims 1 to 34, wherein the electrode comprises a low durometer pre-formed housing member coated with an electrically conductive member configured to distribute electrical charge evenly in the electrode unit and provide an electrical connection to a connecting member arranged with a flexible matrix member, the matrix member providing for fixing a first liquid-like gel element filled into the matrix member to a level at which the matrix member provides mechanical support for a second rubber-like gel element converted from a sheet of pre-cured hydrogel, which forms a barrier to the liquid gel element and comes into contact with the patient's skin.