Patent Grant
11577074
The present disclosure relates broadly to implantable medical devices and, more particularly, to bioelectronics devices for nerve stimulation and/or monitoring (recording).
Virtually all physiological functions are regulated by neural activity. Accordingly, in the field of bioelectronics, it is frequently desirable to interface nerves in a living organism with an apparatus or device that may be used to stimulate or monitor the nerves. Unfortunately, some current bioelectronics devices suffer from one or more disadvantages. For example, some existing devices can be used only with large nerve branches and/or must be placed on the cortical brain surface. Such locations within the patient can be associated with the regulation of many different physiological functions. Accordingly, some existing devices can provide inconsistent results and/or obscure specific pathways of neural control. Additionally, some current devices are invasively penetrating of the nerve, suitable for use with only severed nerves, and/or difficult to use with nerves having a small diameter, such as a diameter of less than 500 μm. Therefore, there exists a need for improved bioelectronics devices and methods of stimulating and/or monitoring nerves that overcome one or more of the foregoing deficiencies of previous devices and methods.
In one aspect, apparatuses for nerve stimulation and/or monitoring are described herein which, in some cases, can provide one or more advantages compared to other apparatuses. For example, in some embodiments, an apparatus described herein is non-penetrating and removable. An apparatus described herein may also be “closeable” or otherwise able to retain or secure an intact (non-severed) nerve, including an intact nerve having a small diameter. Additionally, in some cases, an apparatus described herein can be made by cost-effective microfabrication techniques and can have small and highly reproducible features. Moreover, an apparatus described herein, in some instances, is able to retain and stimulate and/or monitor an intact nerve while also permitting the nerve freedom of motion within the apparatus, thus preventing or reducing mechanical strain on the nerve.
In some embodiments, an apparatus for nerve stimulation and/or monitoring described herein comprises a top substrate layer, a bottom substrate layer in facing opposition to the top substrate layer, and a channel disposed between the top substrate layer and the bottom substrate layer. Additionally, a plurality of electrodes is disposed on one or more interior surfaces of the channel. Further, the channel can be defined by the top substrate layer, the bottom substrate layer, and a retaining wall that extends at least partially between the top substrate layer and the bottom substrate layer. Moreover, this retaining wall can retain the nerve within the channel of the apparatus. The retaining wall may also retain the nerve in contact with the electrodes. In some implementations, the apparatus further comprises a spacer layer disposed between the top substrate layer and the bottom substrate layer.
In another aspect, methods of stimulating and/or monitoring a nerve are described herein. In some embodiments, such a method comprises placing the nerve in the channel of an apparatus described hereinabove. Moreover, the nerve can be placed in contact with the plurality of electrodes of the apparatus. The method can further comprise sending electrical signals from the electrodes to the nerve and/or receiving electrical signals from the nerve to the electrodes. In addition, in some instances, the top substrate layer and the bottom substrate layer of the apparatus define an opening of the channel at a proximal end of the apparatus, and the method further comprises joining the top substrate layer and the bottom substrate layer to close the opening of the channel at the proximal end of the apparatus following placement of the nerve in the channel. Further, in some cases, the nerve is an intact nerve. Moreover, in some embodiments, the apparatus does not penetrate the nerve when the nerve is placed or retained in the channel. Additionally, in some instances, the nerve is a nerve of a living patient, and the method further comprises placing the apparatus within a biological compartment of the patient. In some such embodiments, the apparatus is sealed within the biological compartment of the patient after the nerve is placed in the channel of the apparatus. Further, such a method can also comprise removing the nerve from the apparatus and removing the apparatus from the patient after sealing the apparatus within the biological compartment of the patient. Additionally, in some embodiments, a method described herein further comprises sending and/or receiving electrical signals to and/or from the nerve, including while the nerve is disposed within a channel of an apparatus described herein.
These and other embodiments are described in greater detail in the detailed description which follows.
Embodiments described herein can be understood more readily by reference to the following detailed description, examples, and figures. Elements, apparatus, and methods described herein, however, are not limited to the specific embodiments presented in the detailed description, examples, and figures. It should be recognized that these embodiments are merely illustrative of the principles of the present invention. Numerous modifications and adaptations will be readily apparent to those of skill in the art without departing from the spirit and scope of the invention.
In addition, all ranges disclosed herein are to be understood to encompass any and all subranges subsumed therein. For example, a stated range of “1.0 to 10.0” should be considered to include any and all subranges beginning with a minimum value of 1.0 or more and ending with a maximum value of 10.0 or less, e.g., 1.0 to 5.3, or 4.7 to 10.0, or 3.6 to 7.9.
All ranges disclosed herein are also to be considered to include the end points of the range, unless expressly stated otherwise. For example, a range of “between 5 and 10” or “from 5 to 10” or “5-10” should generally be considered to include the end points 5 and 10.
Further, when the phrase “up to” is used in connection with an amount or quantity, it is to be understood that the amount is at least a detectable amount or quantity. For example, a material present in an amount “up to” a specified amount can be present from a detectable amount and up to and including the specified amount.
I. Apparatuses for Nerve Stimulation and/or Monitoring
In one aspect, apparatuses for nerve stimulation and/or monitoring are described herein. In some embodiments, such an apparatus comprises a top substrate layer, a bottom substrate layer in facing opposition to the top substrate layer, and a channel disposed between the top substrate layer and the bottom substrate layer. Additionally, a plurality of electrodes can be disposed on one or more interior surfaces of the channel. For example, in some embodiments, top electrodes are disposed on an interior surface of the top surface layer, and bottom electrodes are disposed on an interior surface of the bottom substrate layer.
As described further hereinbelow, the channel of the apparatus can be defined by the top substrate layer, the bottom substrate layer, and a retaining wall extending at least partially between the top substrate layer and the bottom substrate layer. Moreover, the retaining wall can be operable to or can be configured to retain or secure the nerve within the channel of the apparatus. The retaining wall can also retain the nerve in contact with the plurality of electrodes. In addition, in some cases, an apparatus described herein further comprises a spacer layer disposed between the top substrate layer and the bottom substrate layer. The height of this spacer layer can at least partially define a height of the channel. Moreover, in some cases, the top substrate layer and/or the bottom substrate layer comprises a recess, cavity, groove, trough, or furrow. Such a recess can have an elongated shape and define an interior surface of the channel. Thus, in some such instances, the channel of the apparatus is defined by the recess of the top substrate layer, the recess of the bottom substrate layer, and the retaining wall.
Specific components and features of apparatuses according to the present disclosure will now be further described with reference to the figures. It is to be understood that the same reference numerals used in differing figures generally correspond to the same features of an apparatus.
Further, the apparatus (100) also comprises a spacer layer (150) disposed between the top substrate layer (110) and the bottom substrate layer (120). As described further herein, a height of the spacer layer (150) can at least partially define a height (132) of the channel (130) of the apparatus. Additionally, the spacer layer (150) can bond, attach, or affix the top substrate layer (110) to the bottom substrate layer (120). The spacer layer (150) may be formed separately from the top substrate layer (110) and the bottom substrate layer (120), or it may be incorporated into or formed integrally with the top substrate layer (110) and/or the bottom substrate layer (120). In some instances, though not necessarily in the embodiment illustrated in
Moreover, in the embodiment of
It is to be understood that the height of the retaining wall (140), in conjunction with the height (132) and width (134) of the channel (130), can be selected based on the diameter of the nerve, and can be controlled with sub-micron precision. As used herein, a “height of the retaining wall” refers to the sum of the heights of a plurality of aligned retaining walls or the sum of the heights of any subportions of the retaining wall, when a discontinuous retaining wall or a plurality of collinear or “stacked” retaining walls is used. The nerve, once positioned in the channel (130), may experience movement within the channel (130), such that the apparatus does not penetrate the nerve or otherwise damage the nerve if the apparatus is subjected to movement during movement of muscles or other surrounding tissue. Thus, the apparatus need not be mechanically fastened to the nerve; rather, the nerve can be held inside the apparatus by the retaining wall. Additionally, in some cases, the top substrate layer and the bottom substrate layer of an apparatus can be joined or attached at the proximal end of the apparatus to close the opening of the channel, thereby further retaining or securing a nerve within the channel without damaging the nerve. Thus, an apparatus described herein can be non-penetrating to the nerve. “Penetration” of a nerve, for reference purposes herein, can refer to the nerve's entanglement with or growth into a component of a device, or the piercing of the surface of the nerve by an external component. When penetration occurs, it can be very difficult if not impossible to remove the device without damaging the nerve.
Turning again to the channel (130) of the apparatus (100), the channel (130) has a height (132) and a width (134). The height (132) and width (134) may be approximately equal. As shown in
Further, as described above, the size of the retaining wall used to define the channel of an apparatus described herein can be selected based on the height and/or width of the channel, and/or based on the diameter of the nerve to be disposed in the channel. For example, in some cases, the retaining wall is selected to be low enough to permit insertion of the nerve, but high enough to retain the nerve following insertion. As a non-limiting example of proportions, for an apparatus with a channel height of 600 μm and a channel width of 600 μm, a retaining wall height of 200 μm may be appropriate to retain a nerve having a diameter of 500 to 600 μm. In other cases, the retaining wall height may be less than 200 μm or greater than 200 μm. In some embodiments, the retaining wall height is up to 300 μm. Moreover, as described above, it is to be understood that the height of the retaining wall can be the total height of more than one portion of a discontinuous retaining wall or of a plurality of aligned retaining walls that operate cooperatively to retain a nerve. It is further to be understood that an apparatus having only a single 200 μm retaining wall may be functionally equivalent to an apparatus having two 100 μm, aligned retaining walls.
Additionally, in some instances, the height of the channel is 1.5 to 4 times, 2 to 3 times, or 1.75 to 3.5 times the height of the retaining wall. In some embodiments, the channel opening defined by the top substrate layer, the bottom substrate layer, and the retaining wall may be about ⅓ to ½ the height of the channel. In some cases, the width of the channel is 1.5 to 4 times, 2 to 3 times, or 1.75 to 3.5 times a height of the retaining wall. In some embodiments, the channel opening defined by the top substrate layer, the bottom substrate layer, and the retaining wall or walls may be about ⅓ to ½ the width of the channel. Further, in some embodiments, the height of the channel is 1.5 to 3 times a diameter of the nerve. In some cases, the width of the channel is 1.5 to 3 times a diameter of the nerve. Moreover, in some instances, the height of the channel and the width of the channel are substantially equal. Channel height and width may be adjusted independently, but in many cases have similar dimensions. However, the channel cross-section need not be square. Any channel cross-section (square, trapezoidal, rectangular, round, ovoid, etc.) may be used.
The apparatus of
Further, electrodes having an arrangement described herein, such as a longitudinal arrangement of electrodes along the channel length, can provide a means of determining the type of nerve disposed in the channel. As understood by a person of ordinary skill in the art, nerves transmit electrical signals or electrical impulse along a length of the nerve. The known distance between electrodes can thus be correlated with time series data of electrical recordings to estimate conduction velocity along the length of the nerve. Differing nerve fiber types such as alpha motor neuron and group A, B, or C nerve fibers can be classified by conduction velocity. As the signal is transmitted, it will cross each electrode in the plurality of electrodes at a slightly different time, permitting detection of the velocity and intensity of the electrical signal. Further, detecting electrical signals along the same nerve over a period of time (such as a period of time of up to 1 month or greater than 1 month) may be used to monitor the nerve's health and condition over time.
An apparatus described herein may also include one or more electrical interconnects coupling electrodes of the apparatus to an additional component of the apparatus or to an external device, such as a power supply, detector, and/or controller. Such electrical interconnects are illustrated in
Turning again to details of specific components of apparatuses described herein, apparatuses described herein comprise top and bottom substrate layers. The top substrate layer and the bottom substrate layer may be formed from any material not inconsistent with the objectives of the invention. For example, in some cases, the top substrate layer and the bottom substrate layer may be formed from, comprise, consist of, or consist essentially of a flexible material, including a flexible biocompatible polymer. Flexibility of the top substrate layer and the bottom substrate layer may facilitate insertion of the nerve into the channel of the apparatus, allowing for ease of manipulation of the apparatus for placement on the nerve and then for subsequent removal from the nerve. Further, it is to be understood that a “flexible” substrate layer can be elastically or reversibly bent or flexed, without breaking or permanent deformation, from a planar position to a non-planar position through at least 15 degrees, at least 20 degrees, at least 30 degrees, or at least 45 degrees. In some instances, a flexible substrate layer can be flexed or bent through 10-45, 10-30, 15-45, 15-30, 20-45, or 20-30 degrees without breaking or permanently deforming. In some embodiments, the top and/or bottom substrate layer is formed from a polyimide, parylene, a silicone, a polyurethane, or a combination thereof. In some cases, the top and/or bottom substrate layer is formed from poly (4,4′-oxydiphenylene-pyromellitimide), which may be referred to by the trade name KAPTON. Additionally, the top substrate layer and the bottom substrate layer of an apparatus described herein may be fabricated or formed from the same materials, and may have the same or similar shapes and/or sizes. However, the top substrate layer and the bottom substrate layer may also be formed from different materials, and may have dissimilar shapes and sizes.
Further, in some embodiments, the top substrate layer and/or the bottom substrate layer is substantially transparent to light of wavelengths from 400 nm to 700 nm. When the top substrate layer and/or the bottom substrate layer are substantially transparent, visual inspection can determine if there is a nerve in the channel of the apparatus. The substantially transparent top substrate layer and/or the substantially transparent bottom substrate layer can transmit at least 60%, at least 70%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 99% of visible light having wavelengths from 400 nm to 700 nm, from 425 nm to 675 nm, or from 450 nm to 650 nm.
Apparatuses described herein, in some cases, also comprise a spacer layer. The spacer layer may comprise or be formed from any material not inconsistent with the objectives of the present invention, including a material described hereinabove for the top and bottom substrate layers. In some embodiments, the spacer layer may comprise, consist, or consist essentially of a polyimide film with a thermosetting acrylate adhesive film. Additionally, the spacer layer may comprise electronic components such as a miniature wireless module or electrical stimulator circuitry.
Further, a top substrate layer, a bottom substrate layer, and/or a spacer layer of an apparatus described herein may be coated or surface treated to improve the biocompatibility of the apparatus or to reduce inflammation near the apparatus. Any coating not inconsistent with the objectives of the present invention may be used. Coating materials may include, but are not limited to, controlled-release drugs, polyethylene glycol, biomolecules such as proteins, peptides, amino acids, nucleic acids, antibodies or aptamers, or growth factors such as neural growth factor, brain derived growth factor, or any neurotrophins.
In addition, apparatuses described herein comprise electrodes and/or additional electrical interconnects. The electrodes and/or electrical interconnects may be formed from any electrically conductive material not inconsistent with the objectives of the present invention. In some cases, for example, the electrodes comprise, consist of, consist essentially of, or are formed from an inorganic material such as a metal or metal oxide, which may include platinum, copper, gold, or iridium oxide. Electrodes and/or interconnects may also be formed from an organic material such as poly(3,4-ethylenedioxythiophene), polypyrrole, carbon nanotubes, graphene, or a combination thereof. The electrical impedance and charge storage capacity of the electrodes may also have any values not inconsistent with the objectives of the present disclosure. Moreover, the foregoing values may be selected based in part on the exposed area of the electrodes. In some cases, the exposed area of the electrodes can be varied by changing the width of each electrode or by changing the width of the channel in which the electrodes are disposed. In some implementations, the electrodes may be insulated except where they are exposed in the channel. Further, in some cases, the thickness of the insulation corresponds to the retaining wall height. Moreover, any desired number of electrodes may be disposed in a channel of an apparatus described herein. In some embodiments, the number of electrodes ranges from 1 to 64, 2 to 32, or 4 to 20 electrodes. Other numbers of electrodes may also be used.
In addition, in some cases, the flexible nature of the top substrate layer and/or the bottom substrate layer may result in cracking or delamination of an electrode material from the substrate during bending and stretching of the apparatus. In some such embodiments, this difficulty may be overcome by patterning electrode materials in a serpentine pattern to accommodate torsion due to both in plane and out of plane bending. In other embodiments, liquid metal interconnects encapsulated within microfluidic channels may be used to prevent breaking and electrical shorts due to torsion.
It is to be understood that apparatuses described herein can have any combination of features, components, or properties described hereinabove not inconsistent with the objectives of the present invention.
II. Methods of Nerve Stimulation and/or Monitoring
In another aspect, methods of stimulating and/or monitoring a nerve are described herein. In some implementations, such a method comprises placing a nerve in the channel of an apparatus described hereinabove in Section I. Any apparatus described hereinabove in Section I may be used. For example, the apparatus can comprise a top substrate layer, a bottom substrate layer in facing opposition to the top substrate layer, and a channel disposed between the top substrate layer and the bottom substrate layer. The apparatus can further comprise a plurality of electrodes disposed on one or more interior surfaces of the channel. Additionally, the channel is defined by the top substrate layer, the bottom substrate layer, and a retaining wall extending at least partially between the top substrate layer and the bottom substrate layer. The retaining wall retains the nerve within the channel. Moreover, placing the nerve in the channel of the apparatus comprises placing the nerve in contact with the plurality of electrodes. The method further comprises sending electrical signals from the electrodes to the nerve and/or receiving electrical signals from the nerve to the electrodes.
In addition, in some cases, the top substrate layer and the bottom substrate layer of the apparatus define an opening of the channel at a proximal end of the apparatus, and placing the nerve in the channel of the apparatus comprises first flexing an end of the top substrate layer away from a corresponding end of the bottom substrate layer to increase the size of the opening of the channel, and subsequently placing the nerve in the channel through the opening of the channel. A method described herein may also comprise joining the top substrate layer and the bottom substrate layer to close the opening of the channel at the proximal end of the apparatus.
As described further herein, the nerve placed in the channel of the apparatus can be an intact or non-severed nerve. Additionally, a method described herein can be carried out without penetrating the nerve within the channel of the apparatus. Moreover, in some cases, the nerve is a nerve of a living patient, and the method further comprises placing the apparatus within a biological compartment of the patient. The biological compartment can be an interior region of the patient's body. A method described herein may also comprise sealing the apparatus within the biological compartment of the patient after placing the nerve in the channel of the apparatus, including by sealing or closing the biological compartment, such as by using sutures or staples. In addition, in some cases, the apparatus is not permanently implanted within the patient, but may instead be removed from the patient following a desired or therapeutic time period. Such an apparatus may accordingly not be solubilized, degraded, or otherwise decomposed in situ, but may instead be removed from the patient intact after a desired time period. In some implementations, the apparatus may be left in the body of the patient for up to a week, a month, a year, a decade, several decades, or many decades. Further, it is generally to be understood that the nerve may not grow into or become physically attached to the apparatus while the apparatus is disposed in the biological compartment, other than being retained within the channel in a manner described herein. Moreover, in some embodiments, removing the apparatus from the patient after a period of time does not damage the nerve. Thus, in some cases, a method described herein further comprises removing the apparatus from the patient after sealing the apparatus within the biological compartment of the patient, and removing the nerve from the apparatus, both without damaging or severing the nerve.
Additionally, in some embodiments, a method described herein further comprises sending and/or receiving electrical signals to and/or from the nerve, including while the nerve is disposed within a channel of an apparatus described herein. Such electrical signals can be sent from and/or received by electrodes of the apparatus. Further, electrical signals exchanged between a nerve and an apparatus can be used to stimulate, monitor, and/or characterize the nerve. For example, in some instances, a method described herein comprises sending electrical signals from electrodes of an apparatus to the nerve disposed in a channel of the apparatus, thereby stimulating the nerve. Electrical signals can be sent to the nerve a plurality of times, including in a temporally periodic, regular, or irregular manner. In other implementations, a method comprises receiving electrical signals with electrodes of an apparatus from a nerve disposed in contact with the electrodes within a channel of the apparatus. As in the case of sending electrical signals, electrical signals may also be received by the electrodes a plurality of times or over a desired period of time. Further, in some embodiments, a method described herein comprises measuring the velocity and/or intensity of an electrical signal or series of electrical signals received from a nerve, including as a function of time and/or distance along the length of the nerve. Moreover, in some cases, comparing time series data between two electrode sites to calculate conduction velocity can be used to identify or distinguish different nerve fiber types, such as sensory or motor neurons.
More generally, methods described herein can be useful for electrical stimulation of a peripheral nerve intended to cause a physiological response or to provide therapy to the nerve. In addition, methods described herein can be useful for the diagnosis of conditions by combinations of electrical stimulation, recording of neural activity, and monitoring changes of other biometrics caused by stimulation. Further, some methods can provide electrical stimulation intended to mimic sensory perception such as touch feedback from a prosthetic device. Further still, some methods described herein can be useful for monitoring either endogenous or stimulated neural activity for the purpose of determining appropriate electrical stimulation to be delivered through an apparatus described herein either manually or by a feedback control mechanism. In addition, methods described herein can be useful for recording neural activity to be used as a control signal for driving prosthetics or any other electronic or mechanical device.
Specific steps of methods according to the present disclosure will now be further described with reference to the figures. It is to be understood that the same reference numerals used in differing figures generally correspond to the same steps of a method or features of an apparatus.
In the step illustrated in
Further, although not illustrated in
In addition, in some implementations, a vacuum tool may be used to carry out one or more of the steps illustrated in
It is to be understood that methods described herein can include any combination of steps and/or any combination of apparatus features, components, or properties described hereinabove not inconsistent with the objectives of the present invention.
An apparatus for nerve stimulation and/or monitoring according to one embodiment described herein was prepared as follows. A top substrate layer having electrodes and a bottom substrate layer having electrodes were made using conventional microfabrication methods, including photolithographic patterning and sputter deposition of thin films. Specifically, to form a substrate layer, a pre-fabricated substrate formed from a KAPTON polyimide film (thickness=75 μm) was mounted on a silicon wafer for processing. A metal pattern forming the electrodes and metal interconnects was then deposited using platinum as the metal. A spinnable polyimide solution was next applied to achieve a desired recess depth, followed by selective etching to expose the metal electrodes along the channel. Finally, the polyimide film was cured in a nitrogen environment.
A spacer layer (150) was fabricated from an alternating stack of polyimide film and thermosetting polymer to achieve a desired total thickness of the spacer layer (150), as shown in
An apparatus described herein may also be formed by depositing electrode material or otherwise forming electrodes or metal contacts on a substrate, such as a silicon wafer, followed by applying or forming a polyimide film over the functional substrate. In particular, a polyimide solution can be spun on the substrate. In one approach, after spinning the polyimide, the substrate is soft baked to evaporate solvents. Using a photoresist mask, selective wet or dry etching is used to expose the metal pads/contacts/electrodes and to define the channel of the apparatus, lined with electrodes. The polyimide is then further cured in a nitrogen environment to complete the apparatus.
In a second approach, after spinning the polyimide, the substrate is soft baked to evaporate solvents. Photodefinable polyimide is then patterned using a photomask and standard lithography processing. After photolithography patterning and development, the polyimide is then further cured in a nitrogen environment. Finally, a plasma etching process is used to remove residual polyimide from the patterned channel and fully expose the electrode surfaces.
A method for stimulating and/or monitoring a nerve according to one embodiment described herein was carried out as follows. The apparatus of Example 1 was surgically placed on the isolated cutaneous branch of the sciatic nerve of an anesthetized rat. The nerve was specifically placed in the channel of the apparatus in contact with the plurality of electrodes, and 9-0 sutures were inserted through the closure guidance holes to “close” the channel by joining the proximal ends of the top substrate layer and the bottom substrate layer. An electrical signal was then sent from the electrodes to the nerve. The nerve was then removed from the apparatus without causing damage to the nerve, and the apparatus was then removed from the rat.
Various implementations of the disclosure have been described in fulfillment of the various objectives of the disclosure. It should be recognized that these implementations are merely illustrative of the principles of the present disclosure. Numerous modifications and adaptations thereof will be readily apparent to those skilled in the art without departing from the spirit and scope of the disclosure.
This application is the national stage application under 35 U.S.C. § 371 of International Application No. PCT/US2017/021516, filed on Mar. 9, 2017, which claims priority pursuant to 35 U.S.C. § 119(e) to U.S. Provisional Patent Application Ser. No. 62/306,909, filed on Mar. 11, 2016, each of which is hereby incorporated by reference in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2017/021516 | 3/9/2017 | WO |
| Publishing Document | Publishing Date | Country | Kind |
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| WO2017/156232 | 9/14/2017 | WO | A |
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| Number | Date | Country | |
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| 20200078586 A1 | Mar 2020 | US |
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| 62306909 | Mar 2016 | US |
