WO2008109058A1

WO2008109058A1 - Magnetic stimulator

Info

Publication number: WO2008109058A1
Application number: PCT/US2008/002832
Authority: WO
Inventors: P. Michael Finsterwald
Original assignee: Finsterwald P Michael
Priority date: 2007-03-01
Filing date: 2008-03-03
Publication date: 2008-09-12

Abstract

A portable device for the delivery of time-varying magnetic fields to a portion of a subject's body. The device includes a stimulator incorporating a stimulator coil configured to generate the time-varying magnetic fields over a surface of the stimulator. It further has a rechargeable power source and a portable signal generator to drive the stimulator. The stimulator includes planar spiral coils mounted on a flexible circuit, and the device can receive feedback to optimize performance. The device can be incorporated into footwear, headwear and other garments.

Description

MAGNETIC STIMULATOR

[0001] This application claims the benefit of U.S. provisional Application No. 60/904,330, filed March 1 , 2007, which is incorporated herein by reference for all purposes.

[0002] The present invention relates generally to a medical device to treat a patient using magnetic stimulation, and, more particularly, to a portable, wearable device configured to apply time-varying magnetic waves to the patient's anatomy, and to related methods for the treatment of a patient using low power, pulsed magnetic fields.

BACKGROUND OF THE INVENTION

[0003] Polyneuropathy is a neurological condition in which nerve damage creates pain or numbness usually in the extremities. Diabetics commonly have this condition in the feet. Neuropathy may also be cause by chemotherapy, alcoholism, or other toxins in the body. Currently there is no known cure for this condition and there are limited pharmacological treatments available for the management of associated pain.

[0004] It has been reported that exposure of the feet to magnetic energy increases microcirculation and oxygenation, important factors in the treatment and maintenance of neuropathy in the feet. Accordingly, there has existed a need for a device that applies time varying magnetic fields to the feet, or other portions of the body, the device being low cost and easy to use in order for this therapy to be used as a home management treatment by a large patient population. Preferred embodiments of the present invention satisfy these and other needs, and provide further related advantages. SUMMARY OF THE INVENTION

[0005] In various embodiments, the present invention solves some or all of the needs mentioned above, providing a device that applies time varying magnetic fields to the feet, or other portions of the body, the device being low cost and easy to use in order for this therapy to be used as a home management treatment by a large patient population.

[0006] A portable device under the invention, for the delivery of time-varying magnetic fields to a portion of a subject's body, may include a stimulator, a rechargeable power source, and a signal generator. The stimulator incorporates a stimulator coil configured to generate the time-varying magnetic fields, and defines a body-contact surface configured to conform to the portion of the subject's body. The signal generator is configured to use power from the power source to drive a time-varying current through the flexible coil and thereby create the time-varying magnetic fields. Additionally, the stimulator may be configured as a flexible body that can flex to better conform to the portion of the subject's body.

[0007] Advantageously, the device is small, portable, and provides for stimulators to be widely used by subjects at a reasonable price. The closely conforming stimulator coils focus the available energy on the exact body portion over which stimulation is desired, and thereby minimize both the unintended stimulation of other body portions, and the battery capacity (and therefore size) needed to support this portable unit.

[0008] The stimulator coil may define a generally spiral conductor path substantially parallel to the body-contact surface. This configuration advantageously provides for the stimulator coil to be incorporated into a membrane-shaped stimulator that can fit in small locations, such as the insole of a shoe. This configuration further allows for stimulator coils to be concentrically stacked for increased field strength, and/or partially overlapped for a more even field strength distribution.

[0009] The signal generator may include a controller configured with a memory that stores waveform information, providing the signal generator the ability to vary the type of waveform applied. The waveform information may be mathematical in form, allowing waveforms to be calculated from a minimum amount of information.

[0010] The device may also be provided with a sensor configured to sense a response to the time-varying magnetic fields by the subject's body, and the signal generator may be configured to control the time-varying current based on sensed response. Thus, feedback can be used to control the field strength, field distribution, stimulation time, and other related variables to produce better stimulation results.

[0011] Other features and advantages of the invention will become apparent from the following detailed description of the preferred embodiments, taken with the accompanying drawings, which illustrate, by way of example, the principles of the invention. The detailed description of particular preferred embodiments, as set out below to enable one to build and use an embodiment of the invention, are not intended to limit the enumerated claims, but rather, they are intended to serve as particular examples of the claimed invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a perspective view of an embodiment of a portable device for the delivery of time-varying magnetic fields to a portion of a subject's body.

[0013] Figure 2 is a top plan view of a flexible printed circuit containing two spiral coils, as used in the embodiment depicted in figure 1. [0014] Figure 3 is a system diagram of a driver, as used in the embodiment depicted in figure 1

[0015] Figure 4 is a cross-sectional view of a flexible stimulator and a connector, as used in the embodiment depicted in figure 1 , attached to an arm of a subject.

[0016] Figure 5 is a variation of the embodiment depicted in figure 1.

[0017] Figure 6 is an elevational cross-section view of the flexible printed circuit of Figure 2.

[0018] Figure 7 is an elevational cross-section view of a second embodiment of the invention.

[0019] Figure 8. is an elevational cross-section view of a variation of the embodiment depicted in Figure 7.

[0020] Figure 9 is a cross-section view of another variation of the embodiment depicted in figure 7.

[0021] Figure 10 is an elevational cross-section view of a third embodiment of the invention.

[0022] Figure 11 is a top view of the embodiment depicted in figure 10.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The invention summarized above and defined by the enumerated claims may be better understood by referring to the following detailed description, which should be read with the accompanying drawings. This detailed description of particular preferred embodiments of the invention, set out below to enable one to build and use particular implementations of the invention, is not intended to limit the enumerated claims, but rather, it is intended to provide particular examples of them.

[0024] A means is provided for the application of time varying magnetic fields to a portion of a subject's body, such as a foot. The device can be relatively low cost, and can be easy to use portably or in the subject's home. Typical embodiments of the present invention reside in a portable device that can conform to various portions of the body.

[0025] In use, the device is applied to a specific portion of the subject's body, for example, the soles of the feet. The body portion is then exposed to a dynamic magnetic flux generated by the device for a desired exposure time (e.g., on the order of 30 minutes per day). The exposure time, magnetic flux density and frequency spectrum of the magnetic wave are selected to optimize the desired effects on the body portion (e.g., the reduction of pain in numbness in that portion of the body). Other body portions to be subjected to stimulation could include the legs, arms, hands or head.

[0026] With reference to FIGS. 1-3, a portable device for the delivery of desired time-varying magnetic fields to a portion of a subject's body includes a stimulator in the form of a flexible body 101. The flexible body is attached by^{^} a cable 103 to a driver 105. The flexible body incorporates a flexible circuit 111 that includes two stimulator coils in the form of flexible coils 113 that do not overlap. The driver includes a rechargeable power source 121 such as a high capacity lithium battery, and a signal generator 123 that are structurally interconnected (i.e., structurally held in one position relative to one another) by a driver body 125. The signal generator 123 is configured to use power from the power source 121 to drive a time-varying current through the two flexible coils 113 via the cable 103, which electrically interconnects (i.e., puts in electric communication) the flexible coils and the signal generator.

[0027] The flexible coils 113 are configured to generate the desired time- varying magnetic fields, and the flexible body 101 is configured to be in close proximity with, and conformingly received against, the portion of the subject's body so as to allow for magnetic fields from the coils to stimulate the body portion with a minimum of wasted energy.

[0028] To provide for the flexible body 101 to be highly adaptable, the flexible body is preferably a flexible membrane defining a body-contact surface, and characterized by a thickness (along a dimension normal to the body-contact surface) that is substantially smaller than its length and width. The thickness may be constant over the area of the surface, or may vary through a range of values that are all substantially smaller then the length or width. Because the flexible membrane is flexible, it can assume a variety of shapes, such as a planar shape and a rolled shape, and such as the various shapes formed by the various surfaces of a subject's body. This, the flexible body is configured to flex such that the body-contact surface conforms to the portion of the subject's body. It should be noted that the phrase "body-contact surface" should not be understood to require direct contact with the subject's body. For example, the invention envisions that a sanitary drape could be interposed between the stimulator body-contact surface during use.

[0029] To accommodate both the desired level of flexibility and a desire for the device to be easily cleaned, the flexible body could be made from an appropriate material, such as silicone rubber. The flexible circuit 111 may be embedded within the flexible body, close to and extending parallel with the body-contact surface. [0030] In an alternative variation, the stimulator body-contact surface, without substantial deformation, may be designed to conform to the portion of the subject's body to be simulated. The stimulator may then be configured either as rigid, or as partially pliable, that is, pliable only to the extent necessary to accommodate shape changes that may occur as the portion of the subject's body moves.

[0031] With reference to FIG. 4, the device may further include one or more connecters 131 configured to hold the flexible body 101 with respect to the subject's body such that the flexible coil is conformingly received adjacent a surface 133 of the relevant portion of the subject's body. The connectors could be in the form of an adhesive, an adjustable strap, an elastic strap, a bandage, clothing, or other such devices for conforming and connecting the flexible membrane to a body. The driver may be carried by hand, or can be attached to and worn elsewhere on the subject's body.

[0032] With reference to FIG. 5, in one variation of this embodiment the flexible body 101 and the driver 105 (and therefore the rechargeable power source and signal generator) are structurally interconnected. In the context of this application, it should be understood that the term structurally interconnected (with respect to two items) is defined to mean structurally held in one position relative to one another, and capable of structurally supporting one another.

[0033] Under one example of this variation, the flexible body may be strapped to a subject's body portion (e.g., an arm, a hand or the sole of a foot), with the driver rigidly attached to a connecting portion 141 of the flexible body. The attachment may be detachable, such as by a clip that readily clips onto a mating receptacle. [0034] Under another example of this variation, the attachment may be integral. The signal generator, rechargeable battery and flexible printed circuit coil may be laminated within the flexible body, which can then be worn on the subject's body portion. As with the prior example, this integrated portable magnetic stimulator can be placed on the body, for example on the head, and attached by means of an adjustable strap, bandage, clothing, or the like. An advantage of both examples of this variation is that they can be made without a cable, thereby simplifying the magnetic stimulator for a user.

[0035] In the context of this application, it should be understood that the term integral implies a connection that either cannot be detached, or can be detached only by a disassembly process that would not frequently be attempted by a subject using the device. It should also be understood that the term detachable attachment implies a connection that is not integral.

[0036] With reference to FIGS. 2 and 6, each flexible coil 113 is a flat magnetic coil on a flexible printed circuit 111 containing one or more spiral flat coil conductive layers. The flexible coil defines a generally spiral conductor path substantially parallel to the body-contact surface of the flexible body. An advantage of using a flexible printed circuit flat coil is ease of manufacture and low cost combined with durability and flexibility of the coil when worn in a structurally challenging environment, such as a shoe.

[0037] As an example, each flexible circuit 111 might be constructed with a 1 oz. copper thickness, and form two spiral flat coils that are each approximately 1.5 in x 2.5 in. in area. Each of these spiral coils may have 70 turns with a 6 mil trace width and a 4 mil space between traces 151. An inside end of each coil connects via a through hole 153 to an opposite surface of the flexible circuit, on which that end can extend back to electrically connect to the signal generator. The individual spiral coils are electrically isolated from each other and have separate leads 155 for connection to the signal generator. The electrical resistance of each individual coil is approximately 30 ohms.

[0038] A magnetic wave with spectral frequency range less than 20 kHz might be generated using the signal generator 123 to drive the flexible coils at less than 10 Gauss RMS (average) power of magnetic flux over the area to be stimulated. The magnetic wave may be bipolar (alternating between positive and negative flux) or unipolar (alternating between 0 and either a positive or negative value).

[0039] Additional flat magnetic stimulator coils may be included on the flexible printed circuit. The additional stimulator coils are also driven by the signal generator using power from the power source. The additional stimulator coils may at least partially overlap the first and/or second stimulator coils to provide for increased local magnetic field strength and/or a more even distribution of magnetic field strength. Optionally, such stimulator coils may be made concentric to increase local magnetic field strength.

[0040] In a variation of the embodiment, the flexible coil may be a finely wound wire coil having widings that extend around and along an axis running substantially normal to the body-contact surface. Multiple finely wound wire coils could be distributed across the body-contact surface area, and be connected in series or parallel as required to match electrically to the signal generator. Other coil configurations are also considered within the scope of the invention.

[0041] The signal generator drives time-varying current through the stimulator coils to deliver time-varying magnetic fields to the portion of the subject's body. The signal generator may include a timer circuit that switches the battery current on and off through a Darlington pair arrangement of transistors to the printed circuit coil at varying levels. The delivery of a wide variety of time-varying magnetic waves is within the scope of the invention.

[0042] For example, one possibility under the present invention is the use of a unipolar magnetic wave with frequency of 500 Hz is used and a peak instantaneous flux density of between 0.5 and 8 Gauss (0 to peak) and a DC flux level of between 1 and 5 gauss. Alternatively the driving waveform maybe

AC with a peak instantaneous flux density of between 1 and 16 Gauss (peak to peak) and a DC flux level of approximately 0. The driving signal (output of the signal generator) may substantially be a square wave at 500 Hz. The size (area) of the coil may be approximately 7.5 in², and the stimulation time might be between 30 minutes and 3 hours.

[0043] In another possibility, the magnetic stimulation may be pulsed. Pulses may be delivered by a tone-burst in which a fixed number of cycles of a sinusoidal, square, or triangular wave are transmitted, followed by a period of no transmission, and then repeated. The tone burst frequency might vary between 6 and 22 Hz and the number of cycles between 2 and 8. For example a single pulse, or tone-burst, can be made by transmitting 4 cycles of a 14 Hz sine wave. The period of the tone-burst, or the time between pulses, is then varied for example between 0.6 seconds and 2 seconds. By varying the tone burst frequency, the number of cycles transmitted, and the period (time between bursts) during the application the magnetic stimulation might be made to be more compatible with the body, as opposed to using a fixed frequency and fixed period of stimulation. The stimulus can be made to approximate a Poisson distribution, a Gaussian distribution, or other continuous distribution function.

[0044] With reference to FIG. 3, in yet another possibility, the signal generator may include a controller 161 configured to access a rewritable memory 163. The memory stores waveform information, and the signal generator is configured to control the time-varying current based on the waveform information stored in the memory. As a result, the signal generator may be configured to provide a variety of different types of magnetic stimulation, and it might further be configured to have the types of magnetic stimulation changed or upgraded using an external communication port.

[0045] Optionally, the waveform information may be mathematical information from which a waveform can be calculated. The signal generator would be configured to control the time-varying current based on calculations using the waveform information stored in the memory. As a result, the quantity of waveform information needing to be stored, read and/or input might be significantly reduced.

[0046] With reference to FIG. 4, the device can further include a sensor configured to sense a response to the time-varying magnetic fields by the subject's body. The signal generator may then be configured to control the time-varying current based on sensed response, such as with a feedback circuit configured to guide the body's response to a desired response level. Furthermore, In the case where multiple coils are used, one or more sensors can be used to tailor stimulation levels over a given area to better achieve a desired result.

[0047] Depending on which part of the subject body is to be stimulated, various types of sensors might be used. For example, if the soul of the subject's foot is to be stimulated, the sensor might be pulse oximeter, which would be useful for sensing blood oxygen levels. Likewise, if a subject head is to be stimulated, the sensor might be an electroencephalograph electrode, which would be appropriate for sensing brain wave activity.

[0048] Optionally, an MP3 portable audio player such as iPod Shuffle ® (or other such portable audio player) may be used as the driver. Under this variation, an audio amplifier serves as the signal generator, and is integrated with a rechargeable battery, a memory, and a controller configured to selectively use waveform information read from the memory to drive a time- varying current for use by the stimulator.

[0049] Advantageously, the use of such devices would provide a familiar, user-friendly interface for a subject, who may already have compatible battery chargers and other accessories. Additionally, the infrastructure for providing subjects with updated waveform information (such as over the Internet) is well developed and commercially available. Also, such devices are designed for uniform output power over the life of the battery, while being of low cost and small size.

[0050] In use, it is anticipated that the a 10 minute stereo MP3 file would be generated for a sine wave at 500 Hz (on each channel). The MP3 file would be downloaded to the MP3 player using existing resources such as the Apple iTunes ® software. The MP3 player would be turned on and the volume settings set to maximum. Such settings should provide consistent levels of stimulation from one use to the next. The battery life of the MP3 player is anticipated to be approximately four to five hours in the above described configuration based on existing MP3 players, and would have changeable / upgradable stimulation programming.

[0051] Alternatively, other audio range signal generators are within the scope of the invention. It should be noted that the use of a portable audio player to drive two separate coils, each coil being driven by a separate channel of the audio player, provides for more efficient use of the limited power available on each channel of a given portable audio player. Thus, by using both channels on maximum power, concentrically placed coils can achieve higher levels of stimulation than might otherwise be achieved using the portable audio player. Likewise, by using both channels on maximum power, overlapping but not concentrically placed coils can achieve a wider area of stimulation than might otherwise be achieved using the portable audio player. Moreover, the portable audio player may control the separate channel signals to tailor the levels of stimulation given to separate (though typically close) portions of the body.

[0052] With reference to Fig. 7, another embodiment of a portable device for the delivery of desired time-varying magnetic fields may be specifically configured for use with a subject's foot (and particularly the sole of the foot) while the person is mobile. In this case, the operating environment is very challenging, as the sole of a foot carries the entire body weight, and must flex while walking. In this application, a person is understood to be mobile if they are free of any tether, such as a power cord, and if they are not encumbered by any devices that would significantly limit their ability to transport themselves by their conventional means (e.g., by walking).

[0053] This embodiment includes a stimulator in the form of a flexible body 201. The flexible body is attached by a cable 203 to a driver 205. As before, the flexible body incorporates a flexible circuit 211 that includes two stimulator coils in the form of flexible coils that do not overlap. Similarly this driver also includes a rechargeable power source such as a battery, and a signal generator that are structurally interconnected by a driver body. The signal generator is configured to use power from the power source to drive a time- varying current through the two flexible coils via the cable, which electrically interconnects the flexible coils and the signal generator.

[0054] This embodiment provides an item of footwear that incorporates the stimulator. More particularly, the item of footwear includes a substantially typical shoe upper 271 and a typical shoe outsole 273. The integrated upper and outsole form a structural element configured to receive the subject's foot. In this case, the stimulator is an integral insole that incorporates the flexible circuit and is structurally interconnected to the structural element.

[0055] It is noteworthy that the footwear is not simply a limited orthotic device. The outsole extends across the entire bottom of the foot, providing protection from the ground in the form of a portable surface to walk upon. Moreover, the outsole is flexible enough to allow for the flexing of a foot while walking.

[0056] As before, the stimulator has a body-contact surface configured to conform to the portion of the foot to be stimulated. The structural element is configured to conformingly hold the stimulator with respect to the subject's foot such that the stimulator coil is conformingly received adjacent the portion of the subject's foot to be stimulated. It is further configured to maintain the stimulator in this position while the subject is walking, despite the changing shape of the subject's foot that occurs.

[0057] Optionally, the stimulator may be a flexible body configured to flex such that the body-contact surface conforms to the portion of the subject body. Alternatively, the body-contact surface, without substantial deformation, may be designed to conform to the foot. The stimulator may then be configured either as rigid, or as partially pliable, that is, pliable only to the extent necessary to accommodate shape changes that may occur as the portion of the subject's body moves. The rigid and partially pliable options may be particularly useful when the stimulator is used on body portions that may require support (e.g., when the stimulator is incorporated into an insole).

[0058] The structural element upper typically will be in the form of a shoe upper, protecting and covering most or all of the foot. To conceal the presence of the device, the structural element may appear as a typical shoe. [0059] The item of footwear may be a completely custom-designed item, or it may be a commercially available item which has had its insole removed and replaced with an insole having a stimulator coil.

[0060] As depicted in FIG. 7, in this embodiment the integrated driver, including the signal generator and the rechargeable power source, are structurally interconnected to the structural element (e.g., on the upper). The connection may be detachable from the structural element, such as using a clip that readily clips onto a mating receptacle, or the connection may be integral.

[0061] The structural element may form a heel. As depicted in FIG. 8, in a variation of this embodiment, the integrated driver, including the signal generator and the rechargeable power source, are incorporated into the heel, and are thus integral with the item of footwear.

[0062] While it is apparent from the figures that the item of footwear can be a shoe, a slipper, a boot or the like, it should be noted that numerous other variations exist. In a distantly related embodiment, the structural element could also be a sock on which a stimulator is mounted (as depicted in FIG. 9).

[0063] While the above described items of footwear are custom items, such as a shoe having its integral insole removed and a stimulator insole integrally attached, other embodiments may be designed as inserts to be placed within standard footwear. For example, the structural element may consist essentially of an insole that incorporates a rechargeable power source, a signal generator, a cable and a flexible circuit with its stimulator coil, as depicted in FIGS. 10 and 11. In these figures, it can be seen that the insole includes a flexible circuit 301 , a structural element 303, a battery 305, a signal generator 307, and a connector 309 through which the device may be connected to a power source and/or a data source. [0064] As in the previous embodiments, the driver could be an audio signal generator such as an MP3 audio player, but it should be recognized that significant size limitations exist for the driver in this embodiment.

[0065] The invention further includes a method for delivering time-varying magnetic fields to a portion of a subject's body using various embodiments of the portable device, as described above. The method includes the step of mounting the stimulator on the portion of the subject's body such that it can be carried on the subjects body. For embodiments that are wearable articles, such as a shoe, a hat, a scarf, or other garment incorporating a stimulator, this step involves donning the article. For embodiments that must be separately attached, the step involves placing the stimulator against the portion of the subject's body, and attaching it there using an appropriate connector or fastener.

[0066] The method further includes the step of electrically interconnecting the stimulator coil, the signal generator and the rechargeable power source.

Depending on the form of connection, this step may entail connecting one or more wires between the components, or it could entail establishing a wireless connection between one or more of the components, should the system be so designed. The method also includes the step of activating the signal generator to use power from the power source to drive a time-varying current through the stimulator coil such that it delivers time-varying magnetic fields to the portion of the subject's body.

[0067] In the case where the portion of the subject's body includes a portion of the subject's foot, it may be understood that the portable device for the delivery of time-varying magnetic fields is incorporated into an item of footwear that includes a structural element configured to receive the portion of the subject's foot. The item of footwear thus provides for the subject to walk while wearing the item of footwear, and the stimulator is structurally connected to the structural element of the footwear. Thus, in above-described the step of mounting the stimulator on the portion of the subject's body, the structural element conformingly holds the stimulator with respect to the subject's foot such that the stimulator coil is conformingly received adjacent the portion of the subject's foot.

[0068] Likewise, in the case where the portion of the subject's body includes a portion of the subject's head, it may be understood that the portable device for the delivery of time-varying magnetic fields is incorporated into an item of headwear that includes a structural element configured to receive the portion of the subject's head. The item of footwear thus provides for the subject to walk freely while wearing the item of headwear, and the stimulator is structurally connected to the structural element of the headwear. Thus, in above-described the step of mounting the stimulator on the portion of the subject's body, the structural element conformingly holds the stimulator with respect to the subject's head such that the stimulator coil is conformingly received adjacent the portion of the subject's head.

[0069] Furthermore, in the case where the portion of the subject's body is an area of the body between the subject's head and the subject's feet, it may be understood that the portable device for the delivery of time-varying magnetic fields is incorporated into a garment that includes a structural element configured to receive the portion of the subject's body. The garment thus provides for the subject to walk freely while wearing the garment, and the stimulator is structurally connected to the structural element of the garment. Thus, in above-described the step of mounting the stimulator on the portion of the subject's body, the structural element conformingly holds the stimulator with respect to the subject's body such that the stimulator coil is conformingly received adjacent the portion of the subject's body. [0070] In one form of these methods, in the step of activating, the signal generator controls the time-varying current based on waveform information stored in a memory. Moreover, the signal generator may control the time- varying current based on calculations using the waveform information, which is mathematical information from which a waveform can be calculated. Furthermore, the method of use may further include the steps of sensing a response to the time-varying magnetic fields by the subject's body, and then controlling the time-varying current based on the sensed response.

[0071] It is to be understood that the various embodiments of the invention can incorporate various combinations of the above-described features. Alternate variations of these embodiments could comprise other types of signal generators and other types of stimulators. In short, the above disclosed features can be combined in a wide variety of configurations within the anticipated scope of the invention.

[0072] While particular forms of the invention have been illustrated and described, it will be apparent that various modifications can be made without departing from the spirit and scope of the invention. Thus, although the invention has been described in detail with reference only to the preferred embodiments, those having ordinary skill in the art will appreciate that various modifications can be made without departing from the scope of the invention. Accordingly, the invention is not intended to be limited by the above discussion, and is defined with reference to the following claims.

Claims

What is claimed is:

1. A portable device for the delivery of time-varying magnetic fields to a portion of a subject's body, comprising: a stimulator incorporating a stimulator coil configured to generate the time-varying magnetic fields, wherein the stimulator has a body-contact surface configured to conform to the portion of the subject's body; a rechargeable power source; and a signal generator configured to use power from the power source to drive a time-varying current through the stimulator coil; wherein the signal generator includes a controller configured to access a memory; wherein the memory stores waveform information; and wherein the signal generator is configured to control the time-varying current based on the waveform information stored in the memory.

2. The device of claim 1 , wherein: the waveform information is mathematical information from which a waveform can be calculated; and the signal generator is configured to control the time-varying current based on calculations using the waveform information stored in the memory.

3. The device of claim 1 , wherein the signal generator is configured to download and change the waveform information stored in the memory.

4. The device of claim 1 , and further comprising a sensor configured to sense a response to the time-varying magnetic fields by the subject's body, wherein the signal generator is configured to control the time-varying current based on sensed response.

5. The device of claim 1 , wherein the signal generator and rechargeable power source are part of a portable audio player.

6. The device of claim 5, wherein: the portable audio player has a first channel and a second channel; the stimulator incorporates a second stimulator coil configured to generate the time-varying magnetic fields; the first channel is used to drive the first stimulator coil; and the second channel is used to drive the second stimulator coil.

7. The device of claim 6, wherein the first and second stimulator coils are concentric.

8. A device for the delivery of time-varying magnetic fields to a portion of a subject's body, comprising: a stimulator incorporating a stimulator coil configured to generate the time-varying magnetic fields; a power source; a signal generator configured to use power from the power source to drive a time-varying current through the stimulator coil; and a sensor configured to sense a response to the time-varying magnetic fields by the subject's body, wherein the signal generator is configured to control the time-varying current based on sensed response.

9. A portable device for the delivery of time-varying magnetic fields to a portion of a subject's body comprising: a stimulator incorporating a stimulator coil configured to generate the time-varying magnetic fields, wherein the stimulator has a body-contact surface configured to conform to the portion of the subject's body; a rechargeable power source; and a signal generator configured to use power from the power source to drive a time-varying current through the stimulator coil; wherein the rechargeable power source and the signal generator are integral and configured to be carried by the subject.

10. The device claim 9, wherein the stimulator, the rechargeable power source and the signal generator are structurally interconnected.

11. The device claim 10, wherein the connection between the stimulator, and the integral power source and signal generator is detachable.

12. An item of footwear for being received on a subject's foot and for the delivery of time-varying magnetic fields to a portion of the subject's foot, comprising: a stimulator incorporating a stimulator coil configured to generate the time-varying magnetic fields, wherein the stimulator has a body-contact surface configured to conform to the portion of the subject's body; a rechargeable power source; and a signal generator configured to use power from the power source to drive a time-varying current through the stimulator coil; a structural element including an outsole configured to extend across the entire bottom of the subject's foot, wherein the outsole is flexible enough to allow for the flexing of the subject's foot while walking; wherein the stimulator is positioned to be interposed between the outsole and the subject's foot when the footwear is received on the subject's foot; and wherein the structural element is configured to conformingly hold the stimulator with respect to the subject's foot such that the stimulator coil is conformingly received adjacent the portion of the subject's foot.

13. The item of footwear claim 12, wherein the signal generator and the rechargeable power source are structurally interconnected to the structural element.

14. The item of footwear of claim 13, wherein the signal generator and rechargeable power source form an integrated unit that detachably attaches to the structural element.

15. The item of footwear claim 12, wherein the structural element carries an insole; and wherein the stimulator coil is incorporated into the insole.

16. The item of footwear claim 12, wherein the structural element includes a heel; and wherein the rechargeable power source is incorporated into the heel.

17. A stimulation insole for being received on a subject's foot, and for the delivery of time-varying magnetic fields to a portion of the subject's foot, consisting essentially of a body configured to be received within an item of footwear, the body incorporating: a stimulator coil configured to generate the time-varying magnetic fields, wherein the stimulator coil has a body-contact surface configured to conform to the portion of the subject's foot; a rechargeable power source; and a signal generator configured to use power from the power source to drive a time-varying current through the stimulator coil.

18. A method for delivering time-varying magnetic fields to a portion of a subject's body using the portable device for the delivery of time-varying magnetic fields of claim 1 , comprising: mounting the stimulator on the portion of the subject's body such that it can be carried on the subjects body; electrically interconnecting the stimulator coil, the signal generator and the rechargeable power source; and activating the signal generator to use power from the power source to drive a time-varying current through the stimulator coil such that it delivers time-varying magnetic fields to the portion of the subject's body.

19. The method of claim 18, wherein the step of activating includes the steps of: sensing a response to the time-varying magnetic fields by the subject's body; and controlling the time-varying current based on the sensed response.