COMPACT AURICULAR STIMULATION DEVICE

Abstract

Disclosed are nerve stimulation assemblies adapted to apply stimulation signals to a person's nervous system. The assemblies are adapted to apply such signals to nerves terminating on the outer ear of a person, for example, the auricular branch of the vagus nerve. The assemblies comprise an ear canal extension adapted to fit within an ear canal of the person, a housing connected with the extension, and an electrode arm connected with the housing by a connection member. The connection member is adapted to articulate the electrode arm to position the electrode arm relative to the outer ear. An electrode is connected with a distal end of the arm. When the arm is articulated to a selected orientation and the extension is fitted in the ear canal, the electrode is in electrical contact with a portion of the outer ear innervated by a selected peripheral nerve, such as the vagus nerve.

Claims

1. A pair of nerve stimulation assemblies, each assembly comprising: an ear canal extension adapted to fit within an ear canal of an organism; a housing connected with the extension; an electrode arm connected with the housing by a connection member at a proximal end of the arm, wherein the connection member is adapted to articulate the electrode arm to position the electrode arm relative to an outer ear of the organism; and an electrode connected with a distal end of the arm, wherein when the arm is articulated to a selected orientation and the extension is fitted in the ear canal, the electrode is adapted to be in electrical contact with a portion of the outer ear innervated by a peripheral nerve of the organism.

2. The assemblies of claim 1, further comprising a nerve stimulation circuit, the circuit connected with the electrode, wherein the circuit generates an electrical stimulation signal and delivers the stimulation signal to the peripheral nerve via the electrode.

3. The assemblies of claim 1, wherein the ear canal extension is not connected with the stimulation circuit.

4. The assemblies of claim 1, wherein the ear canal extension comprises an electrical insulator at least where the extension contacts the outer ear when the extension is fitted in the ear canal.

5. The assemblies of claim 2, wherein the stimulation signal comprises a waveform applied to the electrodes of the respective assemblies and, for at least a portion of the waveform, a selected first one of the electrodes is at a different voltage relative to a selected second one of the electrodes.

6. The assemblies of claim 1, wherein the electrodes are removably connected with the arms.

7. The assemblies of claim 6, wherein the electrodes are formed from one or more of carbon-loaded silicone rubber, carbon-infused foam, a solid hydrogel, a high conductivity polymer, and a PEDOT coating.

8. The assemblies of claim 1, wherein the electrodes comprise an absorbent material and an electrolyte solution in the absorbent material.

9. The assemblies of claim 1, wherein the arm comprises a first section extending along a longitudinal axis from the proximal end to a bend and a second section extending from the bend to the distal end and wherein the connection member is adapted to allow rotation of the arm about the longitudinal axis relative to the housing.

10. The assemblies of claim 9, wherein the connection member is adapted to allow adjustment of the extension of the first section relative to the housing along the longitudinal axis.

11. The assemblies of claim 9, wherein the connection member is adapted to allow an angular adjustment of the longitudinal axis relative to the housing.

12. The assemblies of claim 1, wherein the housing and at least a portion of the arm are encased in an elastomeric material.

13. The assemblies of claim 12, wherein the distal portion of the arm connected with the electrode is not encased in the elastomeric material, and wherein the elastomeric material is an electrical insulator.

14. The assemblies of claim 1, further comprising an auricle support connected with the housing, the auricle support adapted to fit behind the auricle of the organism when the extension is fitted within the ear canal.

15. The assemblies of claim 2, wherein the nerve stimulation circuit comprises two circuits, one disposed in the housing of each assembly.

16. The assemblies of claim 2, wherein the nerve stimulation circuit comprises a radiofrequency communication circuit adapted to receive a nerve stimulation command and to generate the stimulation signal based on the command.

17. The assemblies of claim 16, wherein the radiofrequency communication circuit comprises a Bluetooth transceiver or a ZigBee transceiver.

18. The assemblies of claim 1, wherein the peripheral nerve is the vagus nerve or the auriculotemporal branch of the trigeminal nerve.

19. The assemblies of claim 2, wherein the nerve stimulation circuit further comprises an impedance detector adapted to determine an impedance between the electrode and the outer ear.

20. The assemblies of claim 19, further comprising a feedback signal generator, the generator adapted to provide a feedback signal to the organism based on the impedance detected by the impedance detector.

21. A system for stimulating nerve tissue in a human comprising: left and right nerve stimulation assemblies, each assembly adapted to fit onto the respective left and right ear of the human, each assembly comprising: an ear canal extension adapted to fit within the respective left and right ear canal of the human; a housing connected with the extension; an electrode connected with the housing and positioned to contact a respective left and right innervated tissue of the human when the ear canal extension is fitted in the respective left and right ear canal of the human; and a waveform generator connected with the electrodes of the left and right nerve stimulation assemblies, wherein the waveform generator generates a stimulation waveform and delivers left and right electrical stimulation signals to the respective electrodes of the left and right assemblies based on the waveform and wherein polarities of the left and right signals are selected so that the waveform is delivered to at least one of the left and right innervated tissue.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] A more complete appreciation of the disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

[0013] FIG. 1 shows a perspective view of an electrode assembly according to an embodiment of the disclosure;

[0014] FIG. 2 shows an electrode assembly according to another embodiment of the disclosure;

[0015] FIGS. 3a and 3b illustrate the anatomy of the human outer ear relative to terminations of the vagus and trigeminal nerves;

[0016] FIG. 4 shows an electrode assembly according to an embodiment of the disclosure adjusted to fit the outer ear of persons with different outer ear anatomy;

[0017] FIG. 5 shows an electrode assembly according to yet another embodiment of the disclosure;

[0018] FIGS. 6a and 6b show a perspective view of an electrode assembly according to yet another embodiment of the disclosure and a block diagram illustrating an arrangement of components according to that embodiment;

[0019] FIGS. 7a and 7b show a perspective view of an electrode assembly according to yet another embodiment of the disclosure and a block diagram illustrating an arrangement of components according to that embodiment; and

[0020] FIGS. 8a and 8b show a perspective view of an electrode assembly according to a still further embodiment of the disclosure and the placement of the assembly in the outer ear of a person.

DETAILED DESCRIPTION

[0021] FIG. 1 shows an electrode assembly 10 according to an embodiment of the disclosure. Housing 6 supports ear canal extension 8. Extension 8 is designed to fit within the ear canal of a person. Extension 8 may include removable/replaceable covers to adjust the diameter of the extension to snugly fit within a person's ear canal.

[0022] Housing 6 is connected with connection member 4. Arm 2 is connected with connection member 4. As illustrated by arrow A, according to one embodiment, arm 2 can extend or retract longitudinally with respect to the connection member 4. As illustrated by arrow B, according to a further embodiment, arm 2 can rotate about its longitudinal axis. Connection member 4 may include stops or other mechanisms that limit the amount of rotation shown by arrow B to prevent over-rotation that could damage electrical connections to arm 2.

[0023] Connection member 4 is connected with housing 6 by a pivot that allows member 4 to swivel, as shown by arrow D, and also to pitch, as shown by arrow E. The various degrees of freedom illustrated by arrows A, B, C, D, and E allow arm 2 to be positioned to adjust the location of electrode 12. Sufficient friction is provided between housing 6 and member 4 and between member 4 and arm 2, so that, once the assembly is configured by adjusting motion indicated by arrows A-E, arm 2 will stay fixed with respect to housing 6 until force is applied to reconfigure the arm.

[0024] An electrode 12 is provided at the distal end of arm 2. Arm 2 and connection member 4 may be formed from a metal or conductive components that provided a conductive path from housing 6 to electrode 12. Alternatively, arm may be formed from a non-conductive material and an electrical conductor such as a wire is provided between housing 6 and electrode 12.

[0025] Electrode 12 is designed to provide an electrical connection with the user's skin, and in particular, with the surface of the user's outer ear. Electrode 12 is preferably made from a flexible material to allow it to be comfortably pressed against the user's skin. According to one embodiment, electrode 12 is formed from silicone rubber or other biocompatible material with a softness selected for comfort. According to one embodiment, the soft material comprising electrode 12 has a hardness on the Shore A scale of about 30 to about 50. According to a preferred embodiment, the soft material has a Shore A hardness of about 40. Where the soft material is non-conductive and biocompatible for skin contact applications, such as silicone rubber, a sufficient concentration of conductive particles, such as carbon particles, carbon nanotubes, metal flakes, and the like are embedded in the material to provide electrical conductivity. As will be described more fully below, an electrical waveform applied to electrode 12 via arm 2 is carried through electrode 12 by the conductive particles and into the person's tissue.

[0026] To provide nerve stimulation, a relatively low impedance connection needs to be made between electrode 12 and the user's skin. According to one embodiment, the contact between electrode 12 and the user's outer ear is enhanced by applying a conductive liquid or semi-liquid material between electrode 12 and the user's skin to decrease skin impedance and facilitate current flow. This material may be a conductive lotion or an electrode gel, such as Spectra 360® by Parker Laboratories, Inc. According to another embodiment, electrode 12 is a carbon infused open cell foam. To reduce impedance and increase current flow, the foam is saturated with an electrolyte solution, such as saline. According to a still further embodiment, electrode 12 is formed from a solid hydrogel material bonded to the surface of a carbon-loaded silicone rubber core. According to one embodiment, electrode 12 is formed using commercially available hydrogel electrode material, such as AG2540, manufactured by Axelgaard Manufacturing Co. Ltd. According to a still further embodiment, a highly conductive polymer, such as poly(3,4-ethylenedioxythiophene) (PEDOT) forms electrode 12 or is applied to the surface of electrode 12 to enhance a low-impedance connection with the user's skin.

[0027] Electrode 12 is fixed to the distal end of arm 2. According to one embodiment, electrode 2 is removable, for example, by being connected with arm 2 via a friction interference fit. According to another embodiment, electrode 12 includes a metal pin or screw that connects with the distal end of arm 2 via a snap fitting or a threaded connection. This allows the electrode 12 to be replaced, for example, when it is worn out or where different users wish to avoid using the same electrode.

[0028] According to another embodiment, electrode 12 is provided in a pre-moistened state by being soaked or coated with a conductive lotion, electrode gel, or electrolyte when it is manufactured, and then provide to the user in a seal package, such as a blister pack. By allowing electrode 12 to be removed and replaced, both reusable and disposable electrodes 12 can be used with the assembly.

[0029] Waveform generator 20 is connected with housing 6 by a wire 22. Within housing 6, circuitry delivers electrical signals from the waveform generator to electrode 12. The assembly 10 may be worn singly, with electrode 12 in contact with a peripheral nerve on either the right ear or left ear. According to a preferred embodiment, a pair of assemblies 10 are provided, one for the left ear and one for the right ear.

[0030] According to a further embodiment, ear canal extension 8 includes an audio speaker. When the assembly is positioned on the outer ear of the person with extension 8 positioned within the person's ear canal, sounds are provided to the person. These may include entertainment, such as music. The sounds may also include feedback signals to assist the person in properly positioning electrode 12 to provide a low-impedance connection to the outer ear. According to a preferred embodiment, ear canal extension 8 is formed from an insulator, such as silicone rubber without conductive particles. This insulation electrically isolates housing 6 from the stimulation signal applied by electrode 12 and limits leakage of the stimulation signal back to the housing and may increase the current applied to person's innervated tissue to improve nerve stimulation.

[0031] FIG. 2 shows left and right electrode assemblies 10a, 10b according to a further embodiment of the disclosure. The same element numbering has been used as in the embodiment of FIG. 1 to show similar structures. In this embodiment, a pair of assemblies is provided. The assemblies 10a, 10b are each shaped to fit onto the persons' respective left and right outer ear. The assemblies 10a, 10b include a housing 6 with an ear canal extension 8 and an over-ear support 30. As shown in FIG. 4, the over-ear support 30 secures each assembly 10a, 10b to the back of the person's respective auricle. This provides a more secure engagement of the assembly with the ear. Electrodes 12a and 12b are connected to their respective housings 6 by an arm. In this embodiment a resilient coating is applied over the arm holding the electrode 12a, 12b as well as over support 30. In the view of FIG. 2, the coating obscures the arm. The resilient coating is sufficiently flexible that the arm can be adjusted, as discussed in the previous embodiment to adjust the position of electrode 12a, 12b with respect to the person's ear. The resilient coating may be formed from a non-conductive material to prevent dissipation of current from the respective electrode to its respective housing 6 and may increase current flowing between electrodes 12a, 12b and hence, the stimulation current flowing through the person's innervated tissue. According to a preferred embodiment, the resilient coating is a non-conductive silicone rubber. As with the previous embodiment, electrode 12a, 12b may be formed from a solid hydrogel material bonded to the surface of a carbon-loaded silicone rubber core. According to one embodiment, using the structure shown in FIG. 2, electrodes 12a, 12b including commercially available hydrogel electrode material, such as AG2540, manufactured by Axelgaard Manufacturing Co. Ltd. and provides skin impedance values from 4000-6000 ohms using a 10 kHz sinusoidal test waveform.

[0032] FIGS. 3a and 3b show the anatomy of the human outer ear. As shown in FIG. 3b, the auricular branch of the vagus nerve terminates in a region adjacent and dorsal of the ear canal that includes the cymba concha. The auriculotemporal branch of the trigeminal nerve terminates in a region ventral and superior to the ear canal and includes the crus of helix of the outer ear. The vagus and auriculotemporal nerves are peripheral nerves that connect with portions of the central nervous system (CNS) that control hormonal, circulatory, respiratory, and digestive activity.

[0033] FIG. 4 shows an assembly according to the embodiment illustrated in FIG. 2 positioned on three human subjects. Ear canal extension 8 is fitted within the subject's ear canal and over-ear support 30 is fitted behind the outer ear auricle. Because the anatomy of the outer ear varies from person to person, the assembly is adjusted by repositioning arm 2 with respect to housing 6 so that electrode 12 is pressed against a selected region of the outer ear (e.g., the cymba conchae to stimulate the vagus nerve). In this configuration, electrical signals applied to electrode 12 are communicated to the vagus nerve. Arm 2 can be repositioned by moving it as indicated by arrows A-E shown in FIG. 1 to contact the crus of helix to contact auriculotemporal branch of the trigeminal nerve or to contact tissue between the crus of helix and cymba conchae innervated by both the vagus and trigeminal nerves.

[0034] FIG. 8a shows a pair of left and right assemblies 10a, 10b according to an alternative embodiment of the disclosure. As with the embodiments described above, ear canal extension 8 extends from housing 6. Arm 2 extends from housing 6 and can be articulated as described with respect to previous embodiments. At the end of arm 2 is electrode 12a, 12b. FIG. 8b shows the assembly of FIG. 8a positioned onto a person's outer ear. Arm 2 is adjusted to position electrodes 12a, 12b in contact with portions of the person's left and right outer ear innervated with a target nerve, for example, the vagus nerve.

[0035] FIG. 5 shows a pair of electrode assemblies 10a, 10b according to another embodiment of the disclosure. The pair of electrode assemblies 10a, 10b are shaped to fit onto the left and right outer ear of the person. The assemblies 10a, 10b are connected with a waveform generator 20 by wires 22a, 22b. The generator 20 includes a wireless communication device 24, such as a Bluetooth transceiver or a ZigBee transceiver. A controller 50 is located in proximity to the generator 20. Controller 50 also includes a wireless communication device 52 adapted to communicate with device 24 of generator 20. The controller 50 could be a custom-made device designed specifically to work with assemblies 10a, 10b and generator 20. Alternatively, controller 50 is a general-purpose device such as a cellular telephone that includes an application allowing it to interact with and control generator 20, for example, using a Bluetooth protocol. According to one embodiment, generator 20 includes an attachment to comfortably and stably connect it with the persons clothing or to their body, such as by a hook, a belt clip, a lanyard, an arm band, or the like. Wires 22a, 22b are sufficiently long to accommodate connection of generator 20. This arrangement allows a device according to the disclosure to be worn while the person engages in physical activities, for example, walking, jogging, running, and the like.

[0036] FIGS. 6a and 6b show yet another embodiment of the disclosure. One or two assemblies 10a, 10b are provided. These assemblies may be configured as shown in the embodiments of FIG. 1, 2, or 8a. Controller 50, such as a cellular phone, is provided in proximity to assemblies 10a, 10b. Controller 50 includes a wireless communication device 52 and software that allows it to interact with and control assemblies 10a, 10b. Assemblies 10a, 10b are connected with one another by wire 22b to deliver a stimulation waveform signal, in opposite polarity, to electrodes 12a and 12b positioned on the opposite ears. As shown in FIG. 6b, circuitry is provided, for example, within assembly 10a (or alternatively assembly 10b) to deliver electrical stimulation signals to electrode 12a (with wire 22a remaining contained within the 10a assembly) and to deliver electrical stimulation signals through wire 22b to electrode 12b. According to one embodiment, this circuitry includes a waveform generator 20 and a power supply 28 such as a rechargeable battery to provide sufficient energy to the generator 20 to deliver nerve stimulation signals. Processor 26 is connected with generator 20. Processor 26 provides signals to the generator 20 that define characteristics of the stimulus signal. These characteristics describe voltage or current of the signal and may include the amplitude, polarity, frequency, wave shape, pulse duration, pulse width, burst duration, inter-burst rest period and other signal characteristics. The preferred shape of the waveform is sinusoidal, but may be square, triangular, or other shapes. According to one embodiment, the waveform can be monophasic, bi-phasic, or have a complex waveform. According to one embodiment, the signal sent to the left and right ear assemblies 10a, 10b are selected to be of opposite polarities. The electrodes 12a, 12b then become alternating anode and cathode pairs that excite innervated tissues on the right and left ear.

[0037] Processor 26 is connected with a transceiver 24 and antenna 28. Radio signals from controller 50 received via antenna 28 are decoded by the processor 26 and used to set the stimulation produced by generator 20.

[0038] FIGS. 7a and 7b show a nerve simulation system according to a further embodiment of the disclosure. As shown in FIG. 7a, a pair of electrode assemblies 10a, 10b are provided. As shown in the block diagram in FIG. 7b, each assembly 10a, 10b includes a nerve stimulation electrode 12 adapted to stimulate a selected nerve ending using, for example, the structures illustrated in FIGS. 1, 2 and/or 8a. An audio speaker 32 is provided in either or both of the assemblies 10a, 10b. Speaker 32 may be positioned within ear canal extension 8 to project sounds into the person's ear canal. Alternatively, speaker 32 may be a bone conduction speaker in contact with the person's skeletal system to provide audio signals to the person. As with previous embodiments, electrode 12 is connected with a waveform generator 20 to provide a nerve stimulation signal to, for example, the person's vagus or trigeminal nerve.

[0039] Also connected with electrode 12 is an impedance detector 34. Impedance detector 34 provides a test signal to electrode 12 and monitors the absorption of the test signal by the person's tissues to determine the contact impedance between electrode 12 and the person's outer ear. Impedance detector 34 measures characteristics of the signal applied by electrode 12, including voltage, current, and phase shift to determine whether a low-impedance contact is made with the person's tissue. According to one embodiment, the test signal includes multiple frequency signals across the range of frequencies that will be used for nerve stimulation. Impedance detector 34 is connected with processor 26. Processor 26 provides an audible signal to the person via speaker 32 that indicates whether a low-impedance connection has been made with electrode 12. According to one embodiment, processor 26 generates a tone with a frequency that is modulated by the contact impedance. According to another embodiment, processor 26 generates a synthesized voice to inform the person when electrode 12 is in proper or improper contact and to inform the user if a low-impedance connection has been lost, for example, because the device has become displaced relative to the person's ear.

[0040] Connections between electrode assemblies 10a, 10b and controller 50 may be via wires 22a, 22b, as shown in FIG. 7a. Alternatively, assemblies 10a, 10b may communicate with controller wirelessly, for example, by radiofrequency signals, infrared signals and the like. According to this embodiment, waveform generator 20, impedance detector 34, and processor 26 are housed in housing 6 of one or the other of assemblies 10a and 10b, along with a suitable power source, for example, a rechargeable battery.

[0041] According to another embodiment, electrode 12 receives electrical signals generated by the person's body, including signals that show activity of the circulatory system, that is, electrocardiography (ECG) signals. ECG information can be used as bio-feedback during or after stimulation. Processor 26 analyzes the electrical signals received via electrodes 12 to determine the effect of stimulation signals on the person's body, such as changes in the ECG signal. ECG related information can also be sent to the mobile device via the wireless connection.

[0042] Heart rate variability (HRV), in particular, has been shown to change during and after auricular vagus nerve stimulation. Spectral analysis of the inter-beat interval has been used to reveal changes in HRV that occur due to the stimulation. See Clancy, Jennifer A. et al. “Non-invasive vagus nerve stimulation in healthy humans reduces sympathetic nerve activity.” Brain stimulation 7.6 (2014): 871-877). Specifically, a decrease in the low frequency to high frequency component ratio of the HRV can be used to confirm correct placement and stimulation. According to one embodiment, processor 26 and/or controller 50 includes circuitry and/or software for analyzing HRV and for generating a feedback signal to indicate correct placement of electrodes 12 relative to the person's tissues.

[0043] While illustrative embodiments of the disclosure have been described and illustrated above, it should be understood that these are exemplary of the disclosure and are not to be considered as limiting. Additions, deletions, substitutions, and other modifications can be made without departing from the spirit or scope of the disclosure. Accordingly, the disclosure is not to be considered as limited by the foregoing description.