Patent Description:
TENS (Transcutaneous Electrical Nerve Stimulation) and (NMES Neuromuscular Electrical Stimulation) devices comprises a pulse generator connected to a plurality of electrode pads attached to the skin of a patient. It is common to use single-patient and limited re-use electrode pads as the anode and cathode on the patient's skin. The single-patient and limited re-use electrodes typically consist of an electrically conductive sticky hydrogel layer, a similarly sized conductive sheet (typically carbon or graphite) and an external cable connection which is embedded between the sticky hydrogel and the carbon / graphite sheet, the core of the cable being either carbon fibers or copper wires. On the exposed, non-patient, side of the electrode pad is a woven fabric which serves as a substrate / reinforcement and also an insulator to protect the electrical stimulation pulses from unwanted contact.

The single-patient and limited re-use sticky electrodes can be located by the clinician in suitably appropriate areas of limbs or torso in order to stimulate nerves which in turn then either provide pain relief (TENS) or activate muscles (NMES) to provide strengthening of damaged or perhaps inactive muscles. After each treatment of typically <NUM>-<NUM> minutes the sticky electrodes are unpeeled from the patient's skin and normally are disposed of. After each treatment the sticky electrodes are unpeeled from the patient's skin and normally are disposed of. In some cases the clinician may choose to re-use the pads for further treatments on the same patient, however the sticky electrode gel will dry out over time and will therefore have a decline in there electrical conductivity as well as the ability to stick to skin. Re-use might be limited in practical terms to five usages after which the electrode is disposed of and new fresh electrodes used.

Due to the design of the prior art sandwich construction, the distribution of the stimulation pulse declines in intensity as the size of the electrode increases. Some manufacturers of larger electrodes (50x100mm and larger) use double cable connections, equivalent to two co-joined 50x50mm electrodes. Other manufacturers use a longer exposed section of carbon or copper wire in contact with the carbon / graphite sheet. Commercially available pulse generation devices which feel comfortable for the patient when used with 50x50mm single-patient limited re-use electrodes might feel less comfortable when using larger single-patient electrodes as described, the discomfort being apparent in the stimulated limb as a sharp and prickly feeling, often located in one end of the larger electrode.

Further, treatment of different limbs or body parts, on differently sized patients, requires an ability to stimulate differently sized nerves and thus activate differently sized muscles. Prior art electrodes of the above described construction become less effective as they increase in size.

Thus, a need exist for a design and construction of electrode which is multi-patient and multi-reusable, and can be suitably cleaned and disinfected such that it can be used in a hospital or treatment clinic environment across different patients. Preferably, such an electrode would also be able to be scaled in size and improve patient comfort due to more even current distribution without hotspots or edge effects.

Exemplary prior art electrode pads are disclosed in <CIT>, <CIT>, <CIT>, <CIT> and <CIT>.

In view of the above, an object of the present disclosure is to overcome or at least mitigate drawbacks.

In a first aspect the invention relates to an electrode pad for electro-stimulation, comprising:.

In one embodiment, the electrode pad may further comprising an adhesive disposed on a second side of the first non-conductive flexible substrate, and a second non-conductive flexible substrate comprising at least one conductive track disposed on a first side of the second non-conductive flexible substrate, and where a second side of the second non-conductive flexible substrate, opposite the first side of the second non-conductive flexible substrate, is arranged on the adhesive.

In one embodiment, the electrode pad may further comprise a non-conductive silicone layer covering all sides of the electrode pad other than the second side of the layer of conductive silicone.

In one embodiment, the primer may be a non-conductive primer.

In one embodiment, the layer of layer of conductive silicone may be a compression molded layer of conductive silicone.

In one embodiment, the non-conductive flexible substrate may be a polymer printed circuit board.

In one embodiment, the polymer printed circuit board may comprise at least one microcontroller in operational connection with circuitry adapted for at least one of measure and regulate heat, measure movement, and receive and display a pad-ID.

In one embodiment, the at least one conductive track on the first side of the second non-conductive flexible substrate may be a heating element. The heating element may comprise at least one conductive track arranged in a meandering pattern.

In one embodiment, the electrode pad may comprise at least two conductive tracks, wherein each of the conductive tracks is a separate heating element. The heating elements may comprise at least one conductive track arranged in a meandering pattern.

In one embodiment, the adhesive may be an adhesive film.

In a second aspect the invention provides a method of manufacturing an electrode pad for electro-stimulation, the method comprising:.

In one embodiment, the method may further comprising disposing an adhesive on a second side of the first non-conductive flexible substrate, providing a second non-conductive flexible substrate comprising at least one conductive track disposed on a first side of the second non-conductive flexible substrate, and arranging a second side of the second non-conductive flexible substrate, opposite the first side of the second non-conductive flexible substrate, on the adhesive.

In one embodiment, the method may further comprise covering all sides of the electrode pad other than the second side of the layer of conductive silicone with a non-conductive silicone layer.

In one embodiment, the step of disposing a layer of conductive silicone may further comprising placing the first non-conductive flexible substrate in a molding tool, disposing conductive silicone over the at least a first conductive track and the primer in the molding tool, and applying pressure and heat to the molding tool, such that the layer of conductive silicone is compression molded to the first non-conductive flexible substrate.

<FIG> illustrates a cross-section of an exemplary electrode pad <NUM> for treatment of patients using electro-stimulation. The electrode pad comprises a first non-conductive flexible substrate <NUM> comprising at least one conductive track <NUM> disposed on a first side of the non-conductive flexible substrate <NUM>. The non-conductive flexible substrate <NUM> may made of a flexible printed circuit board (PCB) material, e.g. a polyimide material such as Kapton®, polyethylene terephthalate (PET) or other flexible polymers suitable for electronics. The least one conductive track <NUM> may preferably be comprise of copper, but any other suitable conductive material may be used.

Silicone, particularly medical grade silicone, is a well-known effective material for use in medical devices that is flexible, conformable and easy to clean, disinfect and re-use. The electrode pad <NUM> comprises a layer of conductive silicone <NUM>. The layer of conductive silicone <NUM> is arranged to contact the skin of the patient. The conductive silicone preferably comprises of silicone mixed with conductive materials such as carbon, nickel or silver. Silicone does not readily bond to other materials; it is particularly poor in bonding to metals and plastics without an intermediate primer. A primer <NUM> is disposed on the first side of the first non-conductive flexible substrate <NUM> in areas not covered by the at least one conductive track <NUM>. In one embodiment, the primer <NUM> is a non-conductive primer.

The layer of conductive silicone <NUM> is disposed over the at least one conductive track <NUM> and the primer <NUM>. The primer is bonding the first non-conductive flexible substrate <NUM> to the conductive silicone <NUM> providing mechanical contact between the at least one conductive track <NUM> and a first side of the layer of conductive silicone <NUM>. The layer of conductive silicone <NUM> may preferably be a compression molded layer of conductive silicone. This allows the electrically conductive silicone <NUM> to be molded and cured with high pressure applied ensured a high pre-load to the conductive track <NUM> and the conductive silicone <NUM>, whilst bonding the neighboring primed non-conductive flexible substrate <NUM> to the silicone <NUM>. Although no bond exists between the conductive track <NUM> and the silicone <NUM>, this ensures reliable electrical connections. It becomes a mechanically locked contact connection.

In one embodiment, the electrode pad <NUM> further comprising a non-conductive silicone layer <NUM> covering all sides of the electrode pad other than the second side of the layer of conductive silicone <NUM>. The second side of the layer of conductive silicone <NUM> is the side of the conductive silicone <NUM> arranged to contact the skin of the patient.

<FIG> illustrates a cross-section of an exemplary electrode pad <NUM> for treatment of patients using electro-stimulation. In addition to the features of the electrode pad <NUM>, the electrode pad <NUM> further comprises an adhesive <NUM> disposed on a second side of the first non-conductive flexible substrate <NUM>. The adhesive <NUM> may be an adhesive film, such as a double-sided adhesive tape. The electrode pad <NUM> further comprises a second non-conductive flexible substrate <NUM> comprising at least one conductive track <NUM> disposed on a first side of the second non-conductive flexible substrate <NUM>, and where a second side of the second non-conductive flexible substrate <NUM>, opposite the first side of the second non-conductive flexible substrate, is arranged on the adhesive <NUM>. The second non-conductive flexible substrate <NUM> may made of a flexible printed circuit board (PCB) material, e.g. a polyimide material such as Kapton®, polyethylene terephthalate (PET) or other flexible polymers suitable for electronics. The least one conductive track <NUM> may preferably be comprise of copper, but any other suitable conductive material may be used.

The non-conductive flexible substrate <NUM>, <NUM> may in some embodiments be a polymer printed circuit board. The polymer printed circuit board may further comprise at least one least one microcontroller in operational connection with circuitry adapted for at least one of measure and regulate heat, measure movement, and receive and display a pad-ID.

The at least one conductive track <NUM> on the first side of the second substrate <NUM> is preferably a heating element. In one embodiment the at least one conductive track <NUM> is made of copper, <NUM> wide and having a thickness of <NUM>. The least one conductive track <NUM> may preferably be arranged in a meandering pattern such as schematically illustrated in <FIG> further illustrates a heat measuring device <NUM>, such as a thermistor, and connectors <NUM> to the at least one microcontroller. The electrode pad <NUM> may as schematically illustrated in <FIG> comprise at least two conductive tracks 508a, 508b, wherein each of the at least two conductive tracks 508a, 508b is a separate heating element. <FIG> further illustrates that each heating element is provided with a heating measurement device 501a, 501b, such as a thermistor, and a set of connectors <NUM> to the at least one microcontroller. The number of separate heating elements depends on the size of the electrode pad. A 50x50mm electrode pad may have one heating elements, whereas a 50x200mm electrode pad may have three heating elements.

<FIG> illustrates top views of exemplary electrode pads 300a, 300b, 300c according to three embodiments of the electrode pad <NUM>. <FIG> shows for size comparison the size of the layer of conductive silicone <NUM>. The conductive track <NUM> is preferably at an equal distance to the outer perimeter of the layer of conductive silicone <NUM>. The area of the non-conductive flexible substrate <NUM> of the exemplary electrode pads 300a, 300b, 300c is smaller than the area of the layer of conductive silicone <NUM>. Electrode pads 300a and 300c are configured such that the outer perimeter of the non-conductive flexible substrate <NUM> is inwards of the outer edge of the perimeter of the conductive silicone <NUM>. Electrode pad 300b is configured with an opening or cutout in the middle of the non-conductive flexible substrate <NUM>. Such openings and reduced outer perimeter enable the following layer of the silicone, the non-conductive silicone <NUM> to covalently bond to the conductive silicone, thus providing a robust product with reduced dependency on primer-silicone bonding. The conductive track <NUM> of electrode pad 300a is positioned such that at equidistance is maintained between the tracks and the edge and center of the electrode, to achieve an even current distribution. The conductive track <NUM> of the electrode pad 300b is positioned nearer the edge of the electrode pad to achieve a higher current density near the edge of the electrode pad 300b, e.g. edge biased. The conductive track <NUM> of the electrode pad 300c is positioned closer to the center of the electrode to achieve higher current density near the center of the electrode, e.g. center biased.

<FIG> illustrates top view of exemplary electrode pads 400a, 400b, 400c according to three embodiments of the electrode pad <NUM>. <FIG> shows for size comparison the size of the layer of the conductive silicone <NUM>. The conductive track <NUM> is preferably at an equal distance to the outer perimeter of the layer of conductive silicone <NUM>. The area of the non-conductive flexible substrate <NUM> of the exemplary electrode pads 400a, 400b, 400c is similar to the area of the layer of conductive silicone <NUM> as well as the area of the second non-conductive flexible substrate <NUM> to provide electrical and/or thermal insulation to the at least one conductive track <NUM> on the second non-conductive flexible substrate <NUM>. The conductive track <NUM> of electrode pad 400a is positioned such that at equidistance is maintained between the tracks and the edge and center of the electrode, to achieve an even current distribution. The conductive track <NUM> of the electrode pad 400b is positioned nearer the edge of the electrode pad to achieve a higher current density near the edge of the electrode pad 400b, e.g. edge biased. The conductive track <NUM> of the electrode pad 400c is positioned closer to the center of the electrode to achieve higher current density near the center of the electrode, e.g. center biased.

<FIG> is an exploded view of an exemplary electrode pad <NUM> according to an embodiment of the electrode pad <NUM>, 300a, 300b, 300c. The electrode pad <NUM> has a first non-conductive flexible substrate <NUM>. The non-conductive flexible substrate <NUM> comprises a conductive track <NUM> and a primer (not shown) not covering the conductive track <NUM>. The conductive track <NUM> and the primer faces a layer of a layer of conductive silicone <NUM>. The primer is bonding the first non-conductive flexible substrate <NUM> to the conductive silicone <NUM> providing mechanical contact between the at least one conductive track <NUM> and the layer of conductive silicone <NUM>. <FIG> also shows a cable <NUM> for electrical connection to the conductive track <NUM>. The electrode pad <NUM> further comprises a non-conductive silicone layer <NUM> covering all sides of the electrode pad <NUM> other than the side of the layer of conductive silicone <NUM> that is arranged to be positioned against the skin of a patient.

<FIG> is an exploded view of an exemplary electrode pad <NUM> according to an embodiment of the electrode pad <NUM>, 400a, 400b, 400c. The electrode pad <NUM> has a first non-conductive flexible substrate <NUM>. The non-conductive flexible substrate <NUM> comprises a conductive track <NUM> and a primer (not shown) not covering the conductive track <NUM>. The conductive track <NUM> and the primer faces a layer of a layer of conductive silicone <NUM>. The primer is bonding the first non-conductive flexible substrate <NUM> to the conductive silicone <NUM> providing mechanical contact between the at least one conductive track <NUM> and the layer of conductive silicone <NUM>. An adhesive <NUM> is disposed on the side of the first non-conductive flexible substrate <NUM> not facing the conductive silicon <NUM>. A second non-conductive flexible substrate <NUM> comprising a conductive track (not shown) is arranged on the adhesive <NUM>. The second non-conductive substrate <NUM> comprises at least one microcontroller <NUM> in operational connection with circuitry adapted for at least one of measure and regulate heat, measure movement, and/or receive and display a pad-ID. <FIG> also shows a cable <NUM> for electrical connection to the conductive track <NUM> and/or the microcontroller <NUM>. The electrode pad <NUM> further comprises a non-conductive silicone layer <NUM> covering all sides of the electrode pad <NUM> other than the side of the layer of conductive silicone <NUM> that is arranged to be positioned against the skin of a patient.

Prior art electrode pads have cables exiting in the middle of the electrode pad. Such cables often conflict with strapping of the electrode to a patient when pad and cable is wrapped around the limb of a patient. This is particularly problematic when many electrode pads are wrapped to a patient. An advantage of the cables <NUM>, <NUM> illustrated in <FIG> and <FIG>, exiting the electrode pad <NUM>, <NUM> at the corner of the electrode pad <NUM>, <NUM>, is that it allows strapping in all directions.

<FIG> illustrates a cross-section of an exemplary method of manufacturing an electrode pad <NUM> according to an embodiment of the present invention. The method comprising a first step a) providing the first non-conductive flexible substrate <NUM> comprising at least one conductive track <NUM> disposed on a first side of the first non-conductive flexible substrate <NUM>. In the next step b) the at least one conductive track <NUM> is covered with a mask, and the primer <NUM> is disposed on the first side of the first non-conductive flexible substrate <NUM>. Then the mask is removed. Then in step c) the layer of conductive silicone <NUM> is disposed over the at least first conductive track <NUM> and the primer <NUM>, such that the primer is bonding the first non-conductive flexible substrate <NUM> to the conductive silicone <NUM> providing mechanical contact between the at least one conductive track <NUM> and a first side of the layer of conductive silicone <NUM>.

The method may further comprise step d) of covering all sides of the electrode pad <NUM> other than the second side of the layer of conductive silicone <NUM> with a non-conductive silicone layer <NUM>.

The step of disposing a layer of conductive silicone <NUM> may in one preferable embodiment further comprise the steps of placing the first non-conductive flexible substrate <NUM> in a molding tool, disposing conductive silicone <NUM> over the at least a first conductive track <NUM> and the primer <NUM> in the molding tool, and applying pressure and heat to the molding tool, such that the layer of conductive silicone <NUM> is compression molded to the first non-conductive flexible substrate <NUM>. This allows the electrically conductive silicone <NUM> to be molded and cured with high pressure applied ensuring a high pre-load to the conductive track <NUM> and the conductive silicone <NUM>, whilst bonding the neighboring primed non-conductive flexible substrate <NUM> to the silicone <NUM>. Although no bond exists between the conductive track <NUM> and the silicone <NUM>, this ensures reliable electrical connections. It becomes a mechanically locked contact connection. Alternatively, a liquid silicone rubber injection molding method may be used.

<FIG> illustrates a cross-section of an exemplary method of manufacturing an electrode pad <NUM> according to an embodiment of the present invention. The method continues from step c) described above with reference to <FIG>. The method further comprises step e) of disposing an adhesive <NUM> on the second side of the first non-conductive flexible substrate <NUM>. Then the next step f) comprises providing the second non-conductive flexible substrate <NUM> comprising the least one conductive track <NUM> disposed on the first side of the second non-conductive flexible substrate <NUM>. Then the next step g) comprises arranging the second side of the second non-conductive flexible substrate <NUM>, opposite the first side of the second non-conductive flexible substrate <NUM>, on the adhesive <NUM>.

The method may further comprise the step d) of covering all sides of the electrode pad <NUM> other than the second side of the layer of conductive silicone <NUM> with a non-conductive silicone layer <NUM>.

Claim 1:
An electrode pad (<NUM>, <NUM>) for electro-stimulation, comprising:
- a first non-conductive flexible substrate (<NUM>) comprising at least one conductive track (<NUM>) disposed on a first side of the first non-conductive flexible substrate (<NUM>),
- a primer (<NUM>) disposed on the first side of the first non-conductive flexible substrate (<NUM>) in areas not covered by the at least one conductive track (<NUM>),
- a layer of conductive silicone (<NUM>) disposed over the at least one conductive track (<NUM>) and the primer (<NUM>), wherein the primer (<NUM>) is bonding the first non-conductive flexible substrate (<NUM>) to the layer of conductive silicone (<NUM>) providing mechanical contact between the at least one conductive track (<NUM>) and a first side of the layer of conductive silicone (<NUM>).