CA2945350A1 - Electromagnetic therapy device and methods - Google Patents

Abstract

An example system includes an electromagnetic stimulation module for applying an electromagnetic field to bodily tissue. The electromagnetic stimulation module includes an electromagnetic field generator, and an antenna coupled to the generator and arranged to radiate the electromagnetic field, a power source coupled to the generator, and an activator to initiate radiation of the electromagnetic field. The system also includes a negative pressure module for applying negative pressure to bodily tissue. The negative pressure module includes a patch, a tubing coupled of the patch, and a negative pressure generator coupled to the tubing and arranged to induce a negative pressure on an underside of the patch.

Description

Electromagnetic Therapy Device and Methods BACKGROUND
The following description relates to an electromagnetic field radiator that influences the metabolic characteristics of living systems. The techniques may be used to therapeutically promote healing of tissue and treat diseases.
Therapeutic value may be achieved by applying an electromagnetic field to injured bodily tissue. Application of a high-frequency electromagnetic field at a sufficiently low field strength so as not to produce tissue heating may result in a beneficial effect on healing of the tissue.
In some cases effectiveness of the therapeutic effect of the electromagnetic field may be improved by extending the duration of application of the field. The power requirements of the applied field may be reduced and the effectiveness of the treatment increased by extending the treatment duration.
SUMMARY OF THE DISCLOSURE
The present application discloses various systems and techniques for applying an electromagnetic field to bodily tissue.
In on aspect, a system includes an electromagnetic stimulation module. The electromagnetic stimulation module includes an electromagnetic field generator, an antenna coupled to the generator and arranged to radiate the electromagnetic field, a power source coupled to the generator, and an activator to initiate radiation of the electromagnetic field. The system also includes a negative pressure module.
The negative pressure module includes a patch, a tubing coupled of the patch, and a negative pressure generator coupled to the tubing and arranged to induce a negative pressure on an underside of the patch.
Implementations of this aspect may include one or more of the following features:
In some implementations, the electromagnetic field can have a carrier frequency of 27.1 MHz.

In some implementations, the electromagnetic field generator can include an adjustment module for adjusting a property of the electromagnetic field. The property can be a pulse frequency. The adjustment module can be configured to adjust the pulse frequency of the electromagnetic field between 100 Hz and 50 kHz. The property can be a duty cycle. The adjustment module can be configured to adjust the duty cycle between 1% and 50%.
In some implementations, the system can be configured to deliver less than 100 pW/cm2 of energy into a wound site.
In some implementations, the system can be configured to deliver between 100 pW/cm2 and 2 mW/cm2 of energy into a wound site.
In some implementations, the system can be configured to reduce pain at a wound site.
In some implementations, the system can be configured to reduce inflammation at a wound site.
In some implementations, the system can be configured to accelerate healing at a wound site.
In some implementations, the system can be configured to stimulate blood flow at a wound site. The system can be configured to stimulate blood flow by inducing a stochastic resonance.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is an implementation of a therapeutic electromagnetic device depicting an arrangement of the components.
FIG. 2 is an implementation of a therapeutic electromagnetic patch depicting components in layers.
FIG. 3 is a block diagram of an implementation of a therapeutic electromagnetic device.
FIGS. 4A-B illustrate a control waveform and resulting RF waveform.
FIGS. 5A-I illustrate alternative antenna configurations.
FIG. 6 depicts an alternative configuration of a therapeutic electromagnetic device.

2 FIGS. 7A-D depict various applications of a therapeutic electromagnetic device.
FIGS. 8A-B depict an implementation of an enhanced antenna.
FIG. 9 depicts anatomical locations for placement of a therapeutic device.
FIG. 10 shows an example therapeutic electromagnetic device used in combination with a negative pressure therapy device.
FIG. 11 shows a hypothetical relationship between a pulse rate of a carrier signal and the repetition rate of afferent nerve fiber stimulation in a subject.
FIGS. 12A-B show another example therapeutic electromagnetic device.
Like reference symbols in the various drawings indicate like elements.
DETAILED DESCRIPTION
The systems and techniques described here relate to promoting therapeutic healing of tissue, providing prophylaxis for, and treatment of disorders and diseases through the application of an electromagnetic field. The techniques include providing a self-contained miniaturized electromagnetic field generating device that may be applied to bodily tissue. In some implementations the techniques and systems include devices that are disposable and portable.
The generated electromagnetic field can induce alternating current in bodily tissue. The alternating current may be subjected to non-linear electrical characteristics (for example, diode-like rectification) and so generate low frequency electrical potentials having a time dependence the same as the pulse modulation. The low frequency electrical potentials may stimulate cellular communication by, for example, altering the frequency of cellular activation potentials. Cellular communication may promote the healing of inflammation and the reduction of edema.
These techniques also may provide a method of transmission and utilization of the body's capacitance by affixing a transmitting element of the device to conform and fit closely over the bodily tissue, provide a small space and low weight device for field transport and emergency use. Patient compliance with a therapeutic regimen may be important to promote healing of bodily tissue. Patient compliance may be improved by providing a therapeutic device that is self-contained and portable.
Some or all of the components of a therapeutic electromagnetic energy delivery device may be integrated into a control circuit chip to miniaturize the device. The device

3 may be affixed to various parts of the body for prolonged electromagnetic therapy.
Patient compliance to the therapeutic regimen may be improved by embedding or concealing the device into a patch, bandage, pad, wrap, brace, cast, or other injury support device and affixed to the body or taped over the bodily tissue.
The effectiveness of electromagnetic therapy may be improved by extending the treatment duration. Lower power electromagnetic radiation may be applied for a longer period of time than may be necessary for shorter periods of application. The self-contained unit disclosed may promote patient compliance with periods of therapy that may extend over weeks.
io FIG. 1 illustrates an implementation of a therapeutic electromagnetic device 26.
A control circuit chip 18 may provide the functionality for the therapeutic electromagnetic device to operate. An implementation of a control chip 18 is disclosed in association with the description of FIG. 3 and includes a radio frequency (RF) generator. A power source 10 coupled directly or indirectly to the control chip may be used to power the therapeutic electromagnetic device. The power source may include a battery, photovoltaic cell or an electro-chemical cell. An activator 12 is used to activate the device. The activator may include a switch that is a single-use or multiple use type and may be momentary or alternate-action. Actuation of the activator may be accomplished in various ways including by use of pressure, light or electronic signal either remotely or proximately. An antenna 16 is used to emit electromagnetic radiation and a deflector shield 14 may be used to deflect the electromagnetic radiation to the bodily tissue. In an implementation, the antenna 16 and/or deflector 14 may be tuned for electromagnetic energy in the frequency range of 27 0.5Mhz. The therapeutic electromagnetic device also may include a tuning coil 20 which may be used to match the impedance of the antenna 16 to the RF signal generator within the control circuit chip 18. A circuit board 22 may be used to mount the elements of the device and, in some cases, provide coupling between the elements of the device. The circuit board may be comprised of a rigid or flexible material. The assembled device weighs less than 12 grams.
In some implementations, an adhesive material 24 may be used for affixing the therapeutic electromagnetic device to bodily tissue. Adhesive material 24 includes, for example, pharmaceutical grade adhesives. The therapeutic electromagnetic device may be affixed using other single or multiple usage therapeutic delivery devices, which

4

5 include a patch, a bandage, a pad, a brace, a strap, tape, adhesive and a cast. In some implementations, an indicator 28 can be used to provide indicia that the therapeutic electromagnetic device is active. The indicator 28 may include one or more of the following: a visual indicator such as a light emitting diode (LED), lamp or electro-luminescent display; an auditory indicator such as noise generator; or a tactile indicator such as a vibrator. In an implementation, the indicator may be coupled to an electromagnetic field detector in the control circuit chip 18 and indicate the presence or lack of electromagnetic radiation from the device. In various implementations the indicator may be steady, intermittent or pulsed.
The therapeutic electromagnetic device may be enclosed or encapsulated in encapsulants or other potting compounds to reduce the vulnerability of the device to foreign materials including moisture, fluids, fungus, static charges, dirt, particulate matter and dust. The encapsulants, including insulating resins such as epoxies, polyurethanes, and polyesters, may be cast into cavities containing the device components, to insulate, protect, and hold the components in place. The encapsulant also may reduce the vulnerability of the device to environmental factors including air, heat, sunlight, ultraviolet light and spurious electromagnetic fields. In some implementations, a conformal coating may be applied to the device components and couplings to reduce the vulnerability of the device to moisture, fluids, fungus, static charges, dirt, particulate matter and dust.
FIG. 2 illustrates an exploded view of an implementation of the therapeutic electromagnetic device having the components in a layered form. An activation switch 206, a control circuit chip 208, a power source 210, a visual indicator 212 and a tuning coil 204 may be mounted on a top layer and attached to a circuit board 202 to provide coupling between the components. A deflecting shield 218 may be layered under the circuit board 202. Or deflecting shield is a layer or coating of material, having high magnetic permeability, applied directly to circuit board 202. An antenna 214 to radiate electromagnetic energy may be layered under deflecting shield 218 and coupled to the circuit board 202. The deflecting shield 218 may deflect some of the energy radiated from the antenna 214 away from components mounted on the circuit board and toward the bodily tissue. The shape of the antenna is not restricted and some common shapes are depicted in FIGS. 5A-I. The antenna may also comprise separate conductors that do not make electrical contact with each other. In some implementations, the antenna may have a thickness of less than 5 millimeters and diameter of less than 9 centimeters or in other implementations, a length of less than 27 centimeters. The antenna may be incorporated into the circuit board 202.
The shape of the circuit board 202 and deflecting shield 218 may be altered to adapt the therapeutic device to particular applications. The thickness of the device is less than 10 millimeters. In one implementation, an adhesive material 216 such as a pharmaceutical adhesive may be mounted to the bottom layer under antenna 214 to adhere the device to bodily tissue. Other therapeutic delivery devices including a patch, a bandage, a pad, a brace, a strap, tape, adhesive and a cast also may be used. In some implementations, the components may be selected and arranged for specific applications.
Referring to FIG. 6, for example, the therapeutic device 600 may have a generally annular shape in a therapeutic application such as post-operative healing over an eye or breast. In this case, the annular shape defines a hole 602 through which a patient may see while the device is in place.
FIG. 3 is a block diagram of the circuitry of one implementation of a control circuit chip 300 used in a therapeutic electromagnetic device. Optionally, a tuning coil 302 may be included within the control circuit chip 300 or mounted separately.
The components of the control circuit chip 300 may be integrated into one part or may be assembled from discrete components. The control circuit chip 300 includes an electromagnetic field generator 304 comprised of an oscillator 306 and a driver 308.
Logic circuitry 316 coupled to the generator 304 provides an enable signal 312 to the generator 304. The logic circuitry also may provide an LED signal 318 to an indicator circuit 320, which, in turn, may be coupled to an indicator (not shown). Logic circuitry 316 may include discrete components, a programmable logic device (PLD), a microprocessor or other micro-controller unit (MCU). A power source 324 may be used to supply power to the electromagnetic therapy device. An activator 326 controls the flow of power from the power source to a DC to DC converter 328. The activator includes a switch that can provide for a one-time activation and then sustain activation for the duration of life of the power source. The DC to DC converter 328 provides power to the control chip components including the logic circuitry 316, the electromagnetic field generator 304 and an optional RF feedback circuit 314.
The RF
feedback circuit provides an RF radiation signal 330 to the logic circuitry 316. The logic

6 circuitry also may provide an LED signal 318 to an LED indicator circuit and a lock signal 322 to the activator 326.
The electromagnetic field generator 304 comprises an oscillator 306 to generate an electromagnetic field, a driver circuit 308 to receive the electromagnetic field, amplify the wave and to provide the amplified wave to the optional tuning coil 302. The tuning coil 302 may be used to match the impedance of the driver 308 to an antenna 310, which is arranged to radiate the amplified electromagnetic energy. The oscillator 306 may be arranged to produce electromagnetic waves, including sinusoidal waves, at a carrier frequency of 27 +/- 0.5 megahertz (MHz). In an implementation, the io electromagnetic therapeutic device has an average available power of less than approximately 1 milliwatt and a peak available radiated power density of less than 100 microwatts per square centimeter ( W/cm2) measured substantially at the surface of the tissue. The electrical efficiency of average available radiated power generation also may be greater than 20%. Average available power is the power that the device can dissipate into a resistive load. The average available power is distinguished from the power of the carrier within each pulse, which is termed the "peak" power. The peak available radiated power density is the maximum carrier wave power as if it was continuous and not pulsed, divided by the loop area of the antenna. A high voltage generator (not shown) may be included to increase the intensity of the radiated field. The high voltage generator may produce less than 30 VDC and may be synchronized to allow energy transforming action between therapy pulses, so that therapy pulses are not affected by the energy transformation action. Energy transformation could comprise connecting the battery to an inductive coil for a brief duration, and then switching the coil into a diode or rectifier and capacitor. The capacitor accumulates charge at a higher voltage than the battery. When voltage on the capacitor reaches a predetermined value, the capacitor may be discharged into the frequency generator for producing a therapy pulse.
Alternatively, a transformer connected to a rectifier and capacitor as a flyback transformer may replace the inductive coil.
The enable signal 312 may be used to initiate or curtail radiation of the electromagnetic energy. The RF feedback circuit 314 is arranged to detect RF
radiation from the antenna 310 and to provide RF radiation signal 330 to logic circuitry 316.
Based on the level of the RF radiation signal 330, the logic circuitry provides the LED
signal 318 to enable/disable the LED indicator circuit 320, which drives the indicator

7 (not shown) and provides an indication that the antenna is radiating electromagnetic energy. The logic circuitry 316, the LED indicator circuit 320 or the indicator may be arranged so that the indicator is either indicating continuously, intermittently or pulsating. The logic circuitry also may provide the enable signal 312 to enable/disable the electromagnetic field generator 304.
In an embodiment, the energy radiated by the antenna 310 may be pulsed. PEMF
may be used to provide electromagnetic field therapy over long periods of time and reduce heating of the bodily tissue. FIG. 4A illustrates that an enable signal 410 that may be provided from the logic circuit 316 to enable the generation and radiation of io electromagnetic energy. In this example, the enable signal goes to a logic level high every millisecond. The enable pulse level is shown as a logic high but alternatively may be a logic low. In some implementations, the logic high level may be the power source, or regulated non-zero, voltage although other voltages are possible. The illustrated duty cycle is approximately 8% to 10%. In some implementations, the electromagnetic therapeutic device may operate in the frequency range of 3-30 MHz and application of the electromagnetic energy may be pulsed to maximize the therapeutic effect of the field.
Pulses of 100 microsecond (0) pulse duration at intervals of 1 millisecond (mS) (a pulse repetition rate of 1000 Hz) may be preferable. In order to reduce heating of the tissue, the electromagnetic field strength may be limited to less than 100 micro-Watts per square centimeter ( Wcm-2) as measured proximate the surface of the tissue.
FIG. 4B
illustrates a resulting output 412 from the antenna. The electromagnetic field 414 is radiated from the antenna only when the enable signal 410 is at a logic high.
Referring again to FIG. 3, the power source 324 may be direct current (DC) and preferably less than approximately 10 VDC. The power source may be rechargeable.
The rechargeable power source may be a battery of the lithium metal hydride or lithium ion or lithium polymer technology that may be recharged from an external source, including a sine wave field generator proximate the antenna 310 or separate coil (not shown) for the non-contacting induction of power from the external source into the therapeutic device. Current induced in the antenna or separate coil may be rectified and supplied as a reverse current to the rechargeable power source until the power source reaches a predetermined terminal voltage or case temperature.
The power source 324 is coupled to the activator 326. When the activator is actuated, power is coupled to the DC to DC converter which may boost and regulate the

8 power source voltage level. Regulated output voltage from the DC to DC
converter 328 is supplied to the logic circuitry 316, electromagnetic field generator 304 and RF
feedback circuit 314. A lock signal 322 may be provided by the logic circuitry 316 to lock the activator in the "on" position when the activator is actuated at least once.
Optionally, extra input signals 332 and extra output signals 334 may be received and/or provided by the logic circuitry 316 for additional functionality. For example, an output signal may be provided that provides indicia of the level of the voltage level of the power source 324. The output signal may activate a visual or auditory alarm when the power source requires replacement. An output signal may be provided that provides indicia of a state of the bodily tissue. The electrical permittivity and conductivity of tissue affects the frequency of the carrier wave in the device. The ratio of conductivity (6) to permittivity multiplied by angular frequency (co) determines the polarity of the frequency change. If (3 exceeds cog then the carrier frequency decreases. If cog exceeds (3 then the carrier frequency increases. As conductivity is related to pH and free ion concentration, while permittivity is related to abundance of polar molecules and cell membrane charge, the bioelectrical state of the tissue may be assessed by determining the carrier frequency change from that at initial application of the device.
Optionally, the extra output signal 334 may provide control by enhancing the electromagnetic field for directed movement of chemical or pharmaceutical molecules in tissue, such as silver ions, for infection control. The enhanced electromagnetic field may be non-uniform in such a way as to direct movement of polar molecules, a method known as dielectrophoresis. Alternatively, the enhanced electromagnetic field may induce an electric field, which directs the movement of ions, a method known as iontophoresis.
An input 332 may be provided to receive external signals, for example, that alter the electromagnetic pulse duration, duty-cycle or pulse repetition rate of the electromagnetic field generated.
FIGS. 7A-D depict some applications of the therapeutic electromagnetic device.

FIG. 7A depicts a therapeutic electromagnetic device affixed to a knee of a human leg 702. The device may be applied to aid in healing of, for example, a cracked knee, a cut, a sprain or strain. FIG. 7B depicts a therapeutic electromagnetic device 710 affixed to a muscle of a human arm 712 to aid in the healing of, for example, a sprain, a strain or a cut. FIG. 7C depicts a therapeutic electromagnetic device 720 affixed to a human

9 abdomen 722 where, for example, lipo-suction procedures were performed. FIG.

depicts a human face 730 where a therapeutic electromagnetic device 732 is affixed on a left side of the face to aid in healing of an injury such as a tooth cavity.
FIGS. 8A-B depict an implementation of an enhanced antenna comprising wires 802 wound around an annular ring 804 mounted on a printed circuit board 810.
The ring may be a ferrite or magnetic, electrically-insulating ring. The ring may be arranged to support a battery 806 around the periphery. The battery 806 may be held in place by a retaining clip 808 to retain the battery adjacent the printed circuit board 810. Conductors 812 on the printed circuit board may be arranged to function as a main antenna for the o therapeutic electromagnetic device and may be coupled to an electromagnetic field generator (not shown) as described above.
The annular turns of the wires 802 can convey current in phase and frequency with the main antenna 812. The number of turns of wire 802 on the annular ring are arranged to provide a larger magnetic flux than that of the main antenna 812.
The windings cause a magnetic flux to enter/exit the outer perimeter of the annular ring. A
portion of the (alternating) flux impinges bodily tissue underneath the therapeutic electromagnetic device inducing additional alternating current concentric with the main antenna. The additional induced current may result in magnetic flux that could otherwise be generated by a main antenna having a larger diameter. The magnetic field lines 814 from the main antenna conductors on the printed circuit board will take the path of least magnetic reluctance and pass around the underside of the printed circuit board. Only a weak magnetic field impinges the battery 806. The larger portion of the field may be restrained near the main antenna conductors. The effect is to generate increased magnetic field intensity farther in the bodily tissue. Thus, the main antenna, such as a simple loop antenna, with the enhanced antenna windings on the annular ring can present as an antenna with a larger effective diameter.
A simple loop antenna can produce a near field of electromagnetism, which can be confined within a certain volume by the physical geometry of the antenna.
The magnetic field on the axis of a circular loop antenna diminishes in proportion to:

MagneticField ___________________________________ rz2\15 1+
a1 where z is the distance from the center of the loop and a is the radius of the loop.
Beyond a distance Z, the current induced by the magnetic field in the bodily tissue may be ineffective to provide therapeutic value. The distance Z is measured at the point where the surface of the volume intersects the axis. A therapy volume wherein the electromagnetic field induced in the bodily tissue is adequate to have therapeutic value can be determined from the radius, and circularity, of the loop antenna and the current flowing in the antenna. Outside of this volume, therapy may be inadequate.
Inside this volume, therapy may be effective and diminishing on approach to the surface of the therapy volume. In some embodiments, the device effects a penetration of induced 1 o current into the bodily tissue such that a therapeutic response is elicited at a depth of at least 2 cm in the bodily tissue.
A larger effective diameter antenna can increase the magnitude of the induced current and extend the depth of penetration of induced current. Hence, the main antenna with the enhanced antenna may result in current induction inside the bodily tissue over a larger area and to a greater depth than with the main antenna alone.
Method of Using Pulsed Electromagnetic Field (PEMF) Therapy in Certain Diseases Bone and Joint Disorders: The urine of patients with bone and joint disorders typically shows elevated levels of hydroxyproline, hexosamine, creatinine, and uronic acid as a result of metabolic errors in connective tissues surrounding the affected site.
Not only can these errors be corrected with PEMF therapy, but joint pain and swelling can be reduced and mobility of the joint increased. Another major advantage of PEMF
therapy is that it significantly reduces the time required to heal fractured bones. It has also proven to be effective for osteomyelitis, osteoarthritis, rheumatoid arthritis, cervical spondylosis, and lower back pain (including that caused by disc displacement).
Diabetes Mellitus: Blood sugar levels may be slowly reduced to normal or near normal with application of a pulsed electromagnetic field (PEMF). Although the mechanism of action is not completely understood, the evidence obtained thus far indicates that the procedure not only increases the metabolism of glucose in the tissues but also increases the production of insulin and enhances insulin binding to its specific receptors. The therapy has also proven to be effective for gastritis, peptic ulcer, ulcerative colitis, irritable colon, and hemorrhoids.

Bronchial Asthma: Bronchiolar obstruction can be gradually reduced with PEMF
treatment, which liquifies the mucous and facilitates spontaneous clearance.
PEMF
therapy also has anti-inflammatory action, which helps to ensure that the airways remain free and functional. In patients who have undergone the treatment, Forced Vital Capacity, Forced Expiratory Volume, and Peak Expiratory Flow Rates have increased and wheezing and dyspnea have significantly improved. The treatment is also effective for the common cold, tonsillitis, sinusitis, chronic bronchitis, bronchiectasis Cardiovascular Diseases: PEMF therapy is useful in the prevention of heart attacks in hypertensive patients. Treatment helps to lower blood cholesterol levels and increase the circulation of blood by centrally mediating vascular dilatation.
This is particularly important in preventing platelet aggregation and maintaining adequate oxygenation and nutrition of cardiovascular and other tissues. PEMF therapy also effectively disintegrates atherosclerotic plaques. An additional advantage of the procedure is that it blocks the production of free radicals, which play a major role in cardiovascular damage at the cellular level. Other vascular conditions for which PEMF
may be effective are phlebitis, endarteritis, and varicose vein.
Brain and Mind Disorders: Directed through the skull at different points, the PEMF can, by inductive coupling, produce an electric current in specific areas of the brain. It may thus be possible to enhance higher brain functions such as learning, memory, and creative thinking by selective stimulation of certain cells. PEMF
may have broad application as the modality of choice for psychological disorders such as depression, aggression, anxiety, and stress as well as for Parkinson's disease, epilepsy, migraine, stroke, Alzheimer's and other degenerative brain disorders. In addition, cerebral palsy, mental retardation, hyperactivity, learning disabilities may be improved by PEMF stimulation of the central nervous system.
PEMF therapy can increase the efficiency of brain cells in synthesizing the neuro-chemicals required for the transmission of impulses or commands at the synaptic level and by improving the electrical activity of these cells. The brain is a neuro-chemical complex. The efficiency of the brain or intellectual capacity of the brain depends upon the efficient performance of the brain cells and production of the chemicals that are called neurotransmitters.
Too much dopamine can result in hyperactivity, while too little can result in uncoordinated movements of the limbs (Parkinsonism). Less acetylcholine, a neuro-chemical, in the brain is a reason for dementia especially of the Alzheimer's type. If the brain cells are stimulated repeatedly, after showing inhibition, they rebound and become more active than prior to stimulation. Since PEMF has the ability to stabilize the genes and prevent the activity of oxygen free radicals formed in the cells, it helps to retard the aging process.
Genitourinary Conditions: PEMF has been successfully used to treat genitourinary conditions such as menstrual irregularity, sterility, endometritis, and endometriosis in women and orchitis, prostatitis, and oligospermia in men.
Preoperative and Prophylactic Therapy: PEMF therapy over the epigastrium can provide increased blood profusion to the body's extremities to reduce the inflammatory response to injury. Preoperative treatment of the surgical site has also been shown to accelerate healing.
Post-Operative Recovery: PEMF or TENS over 1.5 inches above the wrist line may reduce or ease the nausea for post-surgical recovery, motion sickness or other forms of nausea symptoms such as vomiting.
Non-Contacting Induction of Electrical Current in Tissue Devices described herein can induce current at a high frequency. The amount of current induced by a device is partly proportional to the frequency.
Modulating a carrier waveform, such as the pulse modulation of 27 +/ 0.5Mhz (e.g., 27.1 MHz) in devices described herein, allows a larger current to be produced in a tissue than the pulse modulation waveform alone. The pulse modulation is selected for time and amplitude characteristics appropriate to biological systems. The carrier wave ensures that induced current has a magnitude that is maintained coherently within the pulse modulation. A
varying pulse modulation is sustained by a similar magnitude of induced current.
Rectification occurring in biological systems, such as across cellular membranes, causes the originating pulse modulation waveform to appear as a low frequency voltage.
Membrane capacitance allows induced currents to enter cells much more easily than the pulse modulation waveform would by itself Shunting of current around cells rather than through the cells is also reduced.
No conductive contact of the device with the tissue is required to induce the electrical current in the tissue. The size of the antenna of the device, being much smaller than a wavelength, ensures that the emission is localized to the treatment area.
Accordingly, there is generally little far-field emission that might interfere with, for example, domestic appliances.
o The devices described herein generally induce current at a much higher frequency than tissue-stimulating devices such as, for example, inductive bone-healing stimulators that pulse coils to produce a magnetic field or capacitive stimulators that produce a pulsed electric field.
Positioning of Therapeutic Devices Therapeutic devices such as a PEMF apparatus, a transcutaneous electrical neural stimulator (TENS), or a static magnet array can be positioned at particular points on the body to achieve an enhanced medical therapeutic effect, e.g., accelerate healing, reduce pain, swelling and bruising. TENS operates by causing an electric current to be passed between electrodes placed on the skin over, for example, a painful area.
Devices are described herein that can induce electrical current in a bodily tissue without the use of electrodes that are applied to the skin.
A therapeutic device can be positioned and operated at a specific acupuncture point, including but not limited to the following: the external end of the elbow transverse crease; the depression at the lower border of the malleolus lateralis; below (e.g., about 1 inch below) the lateral extremity of the clavicle at the level of the first intercostals space; between the fourth lumbar vertebra and the fifth lumbar vertebra; 1 inch to the right or left (horizontally) of the position between the fourth lumbar vertebra and the fifth lumbar vertebra; a depression anterior or inferior to the head of the fibula;
about 1.5 inches above the medial border of the patella; between the radius and the palmaris longus; or at a position of pain (e.g., where the pain sensation is the strongest in an individual). FIG. 9 depicts specific anatomical locations where a therapeutic device described herein can be placed on an individual as part of a treatment program (e.g., a treatment for the reduction or elimination of pain).
The therapeutic devices described herein can be used in combination with specific acupuncture positioning techniques to reduce or eliminate pain.
Examples of pain-related disorders include, for example, pain response elicited during tissue injury (e.g., inflammation, infection, and ischemia), pain associated with musculoskeletal disorders (e.g., joint pain such as that associated with arthritis, toothache, and headaches), pain associated with surgery, pain related to irritable bowel syndrome, and chest pain.
In some cases, implementations of the therapeutic devices described above can be used in combination with negative pressure therapy. An example implementation is shown in FIG. 10. In this example, a negative pressure therapy system 1002 is positioned over a wound site 1004. Negative pressure therapy system 1002 includes a patch 1006 and a tubing 1008 coupled via a connecting element 1010. Connecting element 1010 provides an air-tight connection between patch 1006 and tubing 1008, such that an air-tight channel 1010 is defined through the center of tubing 1008, through an aperture 1012 of patch 1006, and through to the underside 1014 of patch 1006. When a negative pressure (e.g., a vacuum or suction force) is applied to the end 1016 of tubing 1008, air is drawn from the underside 1014 of patch 1006 (indicated by dashed arrows 1018), through the aperture 1012 (indicated by dashed arrow 1020), through tubing 1008 (indicated by dashed arrow 1022), and out the end 1016 of tubing 1008.
In an example usage, negative pressure therapy system 1002 is positioned over a wound site 1004, such that the patch 1006 fully or partially covers the wound site 1004.
After the periphery of patch 1006 is securely fastened to the patient's skin 1024 (e.g., using an adhesive material such as an adhesive tape, liquid, or gel), negative pressure is applied to the end 1016 of tubing 1008, causing air to be drawn from the underside 1014 of patch 1006, and creating a suction force on the wound site 1004.
Negative pressure can be applied to the end 1016 of tubing 1008 in a variety of ways. For example, in some implementations, negative pressure can be applied through an air pump (e.g., an electronic and/or mechanical pump that draws air from tubing 1008), a syringe (e.g., an automated or manually operated syringe that draws air from tubing 1008), or any other device capable of exerting a vacuum or suction force of tubing 1008. A range of negative pressure can be applied to tubing 1008. For example, in some implementations, a pressure of approximately -75mmHg to -125mmHG can be applied to tubing 1008, such that a similar pressure is applied to the wound site 1004.
Tubing 1010, patch 1006, and connecting element 1010 can each be made of similar or different materials. In some implementations, tubing 1010, patch 1006, and connecting element 1010 are made of materials that are substantially air-impermeable, such that air can only enter and exit channel 1010 from the ends of the channel. As an example, tubing 1010, patch 1006, and connecting element 1010 can be made of a synthetic or natural plastic, rubber, or other suitable substance. Tubing 1010, patch 1006, and connecting element 1010 can be secured together in various ways, for example using an adhesive substance (e.g., an adhesive tape, liquid, or gel), through frictional fitting between each of the components, or using other securing components (e.g., brackets, clamps, clips, braces, and pins).
Negative pressure therapy system 1002 can be combined with one or more of the therapeutic electromagnetic devices described above. As shown in FIG. 10, an example therapeutic electromagnetic device 1050 can be placed in the vicinity of the wound site 1004 (e.g., around the wound site 1004 and along the periphery of patch 1006), such that electromagnetic radiation is directed into the wound site 1004. Therapeutic electromagnetic device 1050 can be similar to one or more of the electromagnetic devices described above (e.g., device 300 shown in FIG. 3). In this example, therapeutic electromagnetic device 1050 includes an antenna 1052 that extends around the periphery of patch 1006 and encompasses the wound site 1004. Antenna 1052 is coupled to a control module 1054, which houses the other components of the therapeutic electromagnetic device 1050 (e.g., one or more of the components shown in FIG.
3).
During use, in a similar manner as described above, therapeutic electromagnetic device 1050 emits electromagnetic radiation into the wound site 1004, increasing blood circulation in the region.
This combination of negative pressure and increased blood flow can provide a variety of benefits. For example, to heal, wounds ideally need to be maintained in a moist condition, ideally need to have a robust blood supply to the region, and ideally need to be kept warm (i.e., as close to normal body temperature as possible, for example 37 C). By applying a negative pressure to the wound site 1004 (e.g., by using negative pressure therapy system 1002), fluid extravasation from the blood supply in the vicinity of the wound site 1004 is enhanced. Due to this increased influx of fluid, the wound is kept moist. Further, by applying electromagnetic radiation to the wound site 1004 (e.g., by using therapeutic electromagnetic device 1050), the region is provided with an increased supply of blood, which increases oxygen and nutrient delivery to the wound site. Further, as blood flow is a major mechanism by which heat is delivered to the periphery, enhanced blood flow will result in a warming of the wound region.
Thus, by combining negative pressure therapy with enhanced blood flow, a synergistic effect is obtained which significantly increases the rate of wound healing well beyond the effect of either therapy alone, or the expected sum of the effect of the two individual therapies.
Further, this synergistic effect may be particularly beneficial in certain circumstances. For example, in chronic (i.e., non-healing) wounds that occur in the extremities, maintaining adequate blood flow and warmth at the wound site may be a challenge for a healthcare provider. This concern may be compounded if the patient is elderly, or otherwise has relatively poor circulation. The negative pressure therapy system 1002 and the therapeutic electromagnetic device 1050 can be used in conjunction to provide more effective therapy.
In some implementations, negative pressure therapy system 1002 can be used to remove excess fluid from the wound site 1004. As an example, if the wound site contains an excess of fluid, the negative pressure provided by negative pressure therapy system 1002 may cause a portion of this fluid to be drawn out from the wound site 1004 and removed through tubing 1008. As above, therapeutic electromagnetic device also can be used to increase blood circulation to the region. When used in combination, these two systems can improve the speed of healing of certain types of wounds (e.g., bedsores) by simultaneously reducing the swelling and pain of the wound.
Hence, by combining the above blood flow enhancement/wound healing short wave therapy with negative pressure therapy, the wound bed is provided with sufficient blood flow (e.g., to provide oxygen and nutrient delivery), is kept moist, and is maintained at a warm temperature. The combination of these factors can potentially improve the rate of wound healing beyond the rate achieved if only one or two of these three conditions are attained in the wound region.
Various therapeutic modalities can be used to treat pain and edema (i.e., swelling) of injured tissue. For instance, therapeutic electromagnetic device 1050 can provide short wave therapy (SWT) to a wound region. In one example implementation, therapeutic electromagnetic device 1050 is a self-contained, portable, battery operated therapeutic device that operates at approximately 27 MHz, produces pulses at 1 kHz, has an 8-10% duty cycle, produces a peak power of less than 1 mW, and produces an incident radiant power of less than 100 microwatts/cm2. In another example implementation, therapeutic electromagnetic device 1050 operates at approximately 27 MHz, produces pulses at 9 kHz, has a 50% duty cycle, produces a peak power of less than 1 mW. In some cases, one or both of these parameters are sufficient to reduce edema under certain circumstances, suggesting that the therapeutic electromagnetic device 1050 is enhancing interstitial fluid (e.g., lymph) return from the region, resulting in reduced pain.
While example parameters are provided above, these are only examples. Other parameters can be used to provide different effects, for example to provide enhanced blood flow into a region. Particular parameters can be selected based on experimentation.
As an example, in some implementations, therapeutic electromagnetic device 1050 operates at 27.1 MHz (+/- 0.5 MHz), produces pulses at a rate of between approximately 100 Hz ¨ 50kHz (e.g., 100 Hz, 500 Hz, 1 kHz, 2, kHz, 3 kHz, 4 kHz, 5kHz, 6kHz, 7 kHz, 8 kHz, 9kHz, 10 kHz, 11 kHz, 12 kHz, 13 kHz, 14 kHz, 15 kHz, 16 kHz, 17 kHz, 18 kHz, 19 kHz, 20 kHz, 22 kHz, 24 kHz, 26 kHz, 28 kHz, or 50 kHz), has an 5% to 50% duty cycle (e.g., 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50% duty cycle), produces a peak power of between approximately 100 p.W/cm2 to mW/cm2 (e.g., about 250 pW/cm2, about 500 pW/cm2, about 750 pW/cm2, about 1 mW/cm2, about 2 mW/cm2, about 3 mW/cm2, or about 4 mW/cm2), has a treatment area (e.g., antenna area) of between approximately 50 cm2 to 200 cm2, and delivers a total power of between approximately 5 mW to 1000 mW (e.g., 10 mW, 50 mW, 100 mW, 200 mW, 300 mW, 400 mW, 500 mW, 600 mW, 700 mW, 800 mW, or 900 mW) to the tissue (depending on treatment area). In this example, the effects on blood flow are detectable within five minutes of initiating of treatment. As above, while example parameters are provided, these are only examples. Other parameters can be used to provide similar or different effects.
In some cases, the therapeutic electromagnetic device can also operate according to different carrier frequencies. As an example, some therapeutic electromagnetic devices can operate according to a 1 MHz, 5 MHz, 10 MHz, 15 MHz, 20 MHz, 25, MHz, 30 MHz, 35 MHz, 40 MHz, 45 MHz, 50 MHz, or any other carrier frequency.

In some cases, one or more of the parameters can be adjustable by a user or operator in order to induce different patterns of electromagnetic fields (e.g., magnetic fields having different carrier frequencies, pulse frequencies, duty cycles, and/or power).
This can be useful, for example, as it allows a patient or other user to move the device between different locations on the patient, and induce different patterns of electromagnetic fields in each of the different treatment area of the patient's body. As different treatment areas of a patient's body can, in some cases, respond differently to different patterns of electromagnetic fields, this allows a patient or other user to adjust the induced electromagnetic field to achieve an optimal therapeutic response in each particular location. Likewise, this also can be useful, for example, as it allows a user to move the device between multiple patients, and induce different patterns of electromagnetic fields in each of the different patients. As different patients can, in some cases, respond differently to different patterns of electromagnetic fields, this allows a user to adjust the induced electromagnetic field to achieve an optimal therapeutic response in each particular patient.
In some cases, the pulse frequency can be adjustable between 100 Hz and 50 kHz, the duty cycle can be adjustable between 1% and 99%, and/or the peak power can be adjustable between 100 nW/cm2 to 5 mW/cm2. Other adjustment ranges are also possible, depending on the implementation. For example, in some cases, the pulse frequency can be adjustable between 1 kHz and 30 kHz.
The SWT parameters can be adjustable by a user or operator in a variety of ways.
For example, in some cases, the therapeutic electromagnetic device can include an adjustment module having one or more potentiometers that adjustably divide the voltage across one or more portions of the circuitry of the therapeutic electromagnetic device.
As the potentiometer is adjusted, voltages across particular portions of the circuitry are correspondingly changed, resulting in a different electromagnetic energy output. Thus, the user or operator can adjust the one or more potentiometers until a particular set of SWT parameters is achieved (e.g., a particular carrier frequency, pulse frequency, duty cycle, and/or power). In some cases, the potentiometer can be access by the user or operator through a knob, a slider, a dial, a level, or some other suitable input device. As another example, in some cases, the therapeutic electromagnetic device can include an adjustment module having one or more microcontrollers that receive one or more SWT
parameters (e.g., through user input from a key pad, dial, slider, or other suitable input device). In response, the microcontroller can regular the electric energy applied to the circuit (e.g., by applying a signal having a particular voltage, current, frequency, pulse rate, and so forth) in order to achieve the desired SWT parameters (e.g., a particular carrier frequency, pulse frequency, duty cycle, and/or power).
In some cases, parameters can be selected by stimulating a subject using SWT
and varying the SWT parameters (e.g., peak power, pulse rate, duty cycle, carrier frequency, feedback jitter frequencies, and other parameters) in order to achieve a desirable (or otherwise acceptable) degree of electrical nerve stimulation.
This nerve stimulation can provide various benefits. For example, in some implementations, io inducing localized nerve stimulation at the wound site might stimulate vibrations in the tissue of the wound site (e.g., by inducing rapidly cycling periods of muscle contraction and muscle relaxation). This vibration can enhance blood flow and circulation to the wound site, and as a result, can further improve the rate of healing. In some implementations, the SWT parameters can be tuned in order to induce a desired degree of electrical nerve stimulation and tissue vibration.
As an example, FIG. 11 shows a hypothetical relationship between one SWT
parameter, the pulse rate of the carrier signal, and the repetition rate of afferent nerve fiber stimulation in a subject. In this hypothetical example, as pulse rate is increased, the repetition rate of afferent nerve fiber stimulation varies over a range of values. For example, as the pulse rate increases, the repetition rate may peak at a particular pulse rate. This particular pulse rate can be selected for use in SWT. Thus, a maximal repetition rate of afferent nerve fiber stimulation is not achieved simply by maximizing or minimizing a particular SWT parameter, but rather by "tuning" one or more SWT
parameters within a particular range to obtain the desired result.
In practice, however, the repetition rate of afferent nerve fiber stimulation need not always be maximized. For example, in some cases, the SWT parameters can be selected such that a particular repetition rate of afferent nerve fiber stimulation or range of repetition rates is achieved, or such that a localized maximum repetition rate is achieved (as opposed to an absolute maximum repetition rate). This repetition rate or range of repetition rates can also vary, depending on the implementation. In some cases, this repetition rate or range of repetition rates can vary between different locations on a patient or vary between different patients. In some cases, a suitable repetition rate or repetition range of rates can be determined experimentally.

Although FIG. 11 shows an example of how one SWT parameter can be varied in order to select a suitable SWT parameter, this is merely an illustrative example. In practice, multiple SWT parameters can be similarly varied in order to find a suitable set of SWT parameters. In some implementations, SWT parameters can be selected based on factors other than the SWT parameters themselves. As an example, each particular set of SWT parameters might different based on the temperature of the subject's tissue.
In some implementations, SWT parameters might be selected in order to enhance nerve stimulation by inducing a stochastic response. In a stochastic response, a signal can be boosted through the addition of noise (e.g., "white noise," or other noise from a io relatively wide spectrum of frequencies). The frequencies in the noise corresponding to the original signal's frequencies will resonate with each other, amplifying the original signal while not amplifying the rest of the white noise (i.e., inducing a "stochastic resonance"). Accordingly, in some implementations, SWT parameters can be selected in order to intentionally induce noise (e.g., thermal noise) at a wound site in order to amplify the nerve stimulation properties of the induced electromagnetic field.
The amount of noise can be "tuned" in order to provide the desired effect. As an example, SWT parameters might be selected to induce a particular amount of energy (e.g., up to 100 pW/cm2) into a wound site in order to induce a stochastic response, thereby increasing the amount of nerve stimulation induced by the therapeutic electromagnetic device 1050. As another example, the pulse rate of the carrier signal can be increased (e.g., from 1 kHz to 2 kHz, 3 kHz, 4, kHz, 5kKhz, 6 kHz, 9 kHz, 10 kHz, 30 kHz, 50 kHz, and so forth) in order to induce a stochastic response.
As yet another example, the duty cycle of the pulses can be increased (e.g., from 10%
to 50%, 60%, 70%, and so forth) in order to induce a stochastic response. In some implementations, one or more parameters can be simultaneously "tuned." For example, in some implementations, for a 27.1 MHz carrier signal, the energy level can be increased (e.g., from 100 pW/cm2 to 200 pW/cm2, 300 pW/cm2, 400 pW/cm2, 2 mW/cm2 and so forth), the duty cycle can be increased (e.g., from 10% to 70%), and the pulse rate can be increased (e.g., from 1 kHz to 10 kHz) in order to induce a stochastic response. Other parameters are also possible, depending on the implememtation.
In some cases, the therapeutic electromagnetic device might output electromagnetic energy having a particular jitter (e.g., a deviation from true periodicity).
For example, in some cases, counter-electromotive force (commonly known as "back EMF") can be act against the current induced by the therapeutic electromagnetic device, resulting in an increase in current draw from device's power source. In some cases, this current increase can affect the local oscillator and/or the drive circuit of the device, and introduce a jitter.
In some cases, this jitter can introduce additional spectral components of electromagnetic energy into the subject's tissue (e.g., additional harmonic frequencies other than those specified). In some cases, this jitter can have beneficial effects. For example, the additional spectral components, in some cases, that increase the white noise phenomenon found in stochastic resonance effects. Further, in some cases, the additional spectral components introduced by jitter may themselves have a positive therapeutic effect, either alone or in combination with the spectral components associated with otherwise truly periodic electromagnetic energy. Thus, in some cases, jitter can be selectively adjusted in order to obtain a desirable therapeutic result (e.g., using a microprocessor feedback circuit that controls the degree of jitter in the outputted energy). In some cases, a suitable jitter or range of jitters can be determined experimentally.
While several example SWT parameters, tissue temperatures, and spectral responses are described above, these are only examples. In some implementations, SWT
parameters, tissue temperatures, and spectral responses can vary, depending on the application. Further, while in the above examples, parameters are selected based on certain criteria (e.g., to maximize blood flow or nerve stimulation), parameters may be selected based on other criteria. For example, parameters may be selected such that the therapy remains safe to a patient and is power efficient, while providing a specified degree of blood flow, nerve stimulation, and/or heating. Further, blood flow, nerve stimulation, and/or heating need not be maximized in order to provide effective therapy.
As an example, in some implementations, an effective set of SWT parameters might include a 27.1 MHz carrier signal pulsed at 10 kHz. As the magnitude of the carrier signal or pulse duration will have an effect on the heat delivered to the patient (and can potentially harm the patient if too much heat is delivered, or if heat is delivered too quickly), it might be desirable to use therapeutically effective SWT
parameters that avoid a "saturation point," above which little or no additional healing benefits can be obtained. For example, in some implementations, while inducing a particular amount of heat over a relatively short period of time (e.g., 10 minutes) might provide a desired biological effect, in some implementations, it may be preferred to induce this heat over a longer period of time (e.g., 30 minutes, 4 hours, or 8 hours). Prolonging the heating can also potentially reduce the amount of undesired heat generated by the device itself (e.g., heat generated by batteries or power supply due to high current draw), and can potentially improve the power efficiency of the device.
Accordingly, suitable SWT parameters can vary, depending on the application.
Once suitable SWT parameters have been selected, they can be implemented in a variety of ways. As an example, in a pulse rate of approximately 1-3 kHz and a current density of 4 p.A/cm2 are desired to induce 1 mV/cm into a subject's tissue, this results in io approximately 0.1 V/m. In order to induce this voltage, the magnetic field required at 3 kHz is approximately 2 Gauss. For a 10 turn coil of 5 cm, this would require approximately 30 mA, and 24 hour operation would require approximately 500 mAh of electric charge. This can be provided, for example, by two 250 mAh AA sized Li-ion (3.2V) batteries. This example implementation is provided merely as an example. Other implementations are possible, depending on each particular application.
As another example, as an increase in temperature can increase the potential response, a therapeutic electromagnetic device can be used to warm a subject's tissue through RF diathermy. For example, an example therapeutic electromagnetic device might operate at approximately 0.3V/cm at a 10% duty cycle in order to produce approximately 24 [tJ/s/cm3 rms. In this sufficient to produce 15x10-6 C/S, or 0.05 C of heating per hour in skin tissue in the deep tissue. In another example, the therapeutic electromagnetic device might instead operate at approximately three times the current with a duty cycle of 100%, resulting in an output power of approximately 2 mJ/s/cm3, or approximately 4.5 C of heating per hour (assuming not heat loss). As above, these example implementations are provided merely as examples. Other implementations are possible, depending on each particular application.
While an example therapeutic electromagnetic device 1050 is shown in FIG. 10, this is merely one example. Other configurations are possible. For instance, another example therapeutic electromagnetic device 2000 is shown in FIGS. 12A-B, showing the top of the device (FIG. 12A, shown with an antenna 2002) and the bottom of the device (FIG. 12B, shown without antenna 2002). In addition to an antenna 2002, therapeutic electromagnetic device 2000 includes an enclosure 2004. Enclosure 2004 houses batteries 2006a-b, a control module 2008, and radio frequency (RF) drive circuits 2010.

During operation, control module 2008 (using a data processing apparatus, such as a computer processor or application-specific integrated circuit (ASIC)) controls the operation of RF drive circuits 2010 in order to induce an electromagnetic field.
Specifically, RF drives circuits 2010 draw electrical power from batteries 2006a-b, and applies an electrical current to antenna 2002 in order to induce an electromagnetic field.
Control module 2008 can also control RF drive circuits 2010 such that the desired electromagnetic field is induced (e.g., by varying the electric current that is applied to antenna 2002). As shown in FIGS. 12A-B, therapeutic electromagnetic device 2000 also includes a tab 2012, which allows the therapeutic electromagnetic device 2000 to be affixed to the skin of a patient (e.g., using an adhesive substance applied to the lower surface 2014 of tab 2012). After use, therapeutic electromagnetic device 2010 can be removed by peeling tab 2012 from the skin.
In some implementations, a single loop antenna is sufficient to achieve enhancement of blood flow. However, in some implementations, antennas with a multiple loop design may also be effective as long as the antenna is sufficiently compliant to conform to the shape of the body tissue. In some implementations, two or more antennas can be used simultaneously, or in succession. As an example, a single loop antenna might be used for RF diathermy, while a multi-loop antenna might be used for electromagnetic stimulation. These antennas can be driven by two or more different control units, or by the same control unit. Similarly, these antennas can be included in a single device (e.g., in a single shared housing), or in different devices (e.g., in different individual housings).
Other implementations are within the scope of the following claims.

Claims (14)

WHAT IS CLAIMED IS:

1. A system comprising:
an electromagnetic stimulation module comprising:
an electromagnetic field generator;
an antenna coupled to the generator and arranged to radiate the electromagnetic field;
a power source coupled to the generator;
an activator to initiate radiation of the electromagnetic field; and a negative pressure module comprising:
a patch;
a tubing coupled of the patch; and a negative pressure generator coupled to the tubing and arranged to induce a negative pressure on an underside of the patch.

2. The system of claim 1, wherein the electromagnetic field has a carrier frequency of 27.1 MHz.

3. The system of claim 1, wherein the electromagnetic field generator comprises an adjustment module for adjusting a property of the electromagnetic field.

4. The system of claim 1, wherein the property is a pulse frequency.

5. The system of claim 4, wherein the adjustment module is configured to adjust the pulse frequency of the electromagnetic field between 100 Hz and 50 kHz.

6. The system of claim 1, wherein the property is a duty cycle.

7. The system of claim 6, wherein the adjustment module is configured to adjust the duty cycle between 1% and 50%.

8. The system of claim 1, wherein the system is configured to deliver less than 100 µW/cm2 of energy into a wound site.

9. The system of claim 1, wherein the system is configured to deliver between 100 µW/cm2 and 2 mW/cm2 of energy into a wound site.

10. The system of claim 1, wherein the system is configured to reduce pain at a wound site.

11. The system of claim 1, wherein the system is configured to reduce inflammation at a wound site.

12. The system of claim 1, wherein the system is configured to accelerate healing at a wound site.

13. The system of claim 1, wherein the system is configured to stimulate blood flow at a wound site.

14. The system of claim 13, wherein the system is configured to stimulate blood flow by inducing a stochastic resonance.