This patent application relates to pulsed electromagnetic field (PEMF) devices. More particularly, the application relates to PEMF devices where magnetic flux is created by one or more coil positioned in proximity to at least one permanent magnet.
Prior art PEMF devices generate electromagnetic field flux and induce voltage within the body by varying current through a coil. This non-invasive technique produces beneficial results as demonstrated in thousands of studies and research papers over more than five decades. The strength of the electromagnetic field can be increased by increasing the number of coil turns, by increasing current through a coil, or by increasing both the number of coils and the current. Magnetic field flux is designated as dB/dt where the “dB” represents the change in the magnetic field “B” for a time interval “dt”.
Low to medium intensity PEMF devices can produce a peak magnetic field up to about 200 gauss at high pulse frequencies directly from AC or battery power supplies. High intensity “impulse devices” such as transcranial magnetic stimulation (TMS) devices typically produce brief high amperage pulses at a peak intensity of 1,000-25,000+ Gauss, once or twice per second, by charging and discharging capacitors.
A 2003 NASA study reported that fast rise-time pulses promoted a 4× improvement for in vitro stem cell growth, but that sinusoidal pulses were not effective. U.S. Pat. No. 8,376,925 to Dennis et al describes commercial versions of high slew rate trapezoidal-wave pulsed electromagnetic field devices and the ICES-PEMF™, a low to medium intensity PEMF device.
U.S. Pat. No. 10,500,408 to Helekar et al. proposes advantages of a rotating permanent magnet device over conventional TMS devices. Strong permanent magnets can provide a strong magnetic field, but the flux created by rotating magnets is sinusoidal and less that effective than fast rise time coil pulses.
Most PEMF devices are operated at a frequency of 7-100 Hz. Some studies have reported that pathogen-specific “targeted frequencies” between about 1000 Hz and 2 MHz can kill or disable pathogens.
There are two fundamental limitations of coil-based PEMF devices to create effective magnetic field flux within tissue. First, the magnetic field strength drops sharply with distance from the coil with a decrease of 50% in the first 0.5 inch and over 99% in the first 3 inches. Second, it is not practical for an affordable device to create a strong magnetic field with pulse frequencies greater than a few pulses per second.
Applicants suggest that prior art PEMF devices cannot deliver combinations of pulse intensity and pulse frequency that effectively address many ailments. Low or medium intensity devices appear to have insufficient pulse intensity, and high intensity impulse devices appear to be have insufficient pulse frequency, to address many chronic conditions.
In one embodiment, a PERMAFLUX™ PEMF device has a flux module comprising a coil assembly having at least one coil configured in proximity to a permanent magnet assembly with at least one permanent magnet. The permanent magnets deliver a strong and persistent magnetic field deep into tissue. A coil controller employs pulse width modulation and a phase controller to deliver a series of fast-rise-time current pulses to a first coil to “ripple” the magnetic field.
The flux module can deliver a sustained modulation with duty cycles that are orders of magnitude higher than impulse PEMF devices, so PERMAFLUX can exceed the effective dosage of impulse devices by delivering many more pulses at a lower, and more benign, intensity. This ripple creates significant magnetic flux deep into the tissue without the need to recreate a strong magnetic field with each pulse. The pulse duration can be significantly longer than what is practical with many impulse devices.
When the first coil is energized with a positive current direction, the coil generates an electromagnetic field with the same polarity as the magnet assembly and thereby enhances the permanent magnetic field. When the first coil is energized with a negative current direction, the coil generates an electromagnetic field with the opposite polarity as the magnet assembly and thereby partially retracts the permanent magnetic field. A magnetic field flux is produced by the enhancement and retraction of the magnetic field. The device also appears to function as an antenna to transmit the coil electromagnetic field into adjacent tissue. Flux can be provided from a series of positive or negative pulses, an alternating series of positive and negative pulses, or other pulse patterns.
High intensity appears to be important, but not sufficient, to treat chronic ailments. If medium intensity resonant devices could be effective, then they should have been well-established in the last 15 years. Likewise, if impulse devices were effective, then more successes should have been documented in the last 10 years. Applicants suggest that both types of devices can offer some benefit, but that each has a fundamental limitation.
In this specification, the term “PEMF” means pulsed electromagnetic field. The term “PEMF therapy” refers to the use of a PEMF device on a living organism, including the human body; dogs, horses, and other animals; or plants. The embodiments described herein can be considered PEMF devices where one or more coil supplies a pulsed electromagnetic field by “rippling” a permanent magnetic field, or PEMF devices where the combination of a permanent magnet assembly and a coil assembly acts as an antenna to broadcast the electromagnetic fields created by the coil and magnet assemblies.
The term “slew rate” refers to the calculated magnetic flux value “dB/dt” where dB is the change in magnetic field strength B, and “dt” is the change in time. Some PEMF devices with an ultra-fast pulse rise time can yield a high calculated dB/dt, but might have little practical benefit because of the small actual magnetic field intensity.
The term “coil controller” refers to the conversion of a power supply to a series of discrete current pulses to a coil. In some examples, the coil controller may be adjustable to produce various pulse intensities, pulse frequencies, and pulse durations.
“Pulse width modulation” is a method of controlling current to a device by producing trapezoidal waves, where input DC voltage is switched “on” and “off” to create nominal square waves. In this specification, the terms “current control” and “current controller” are used in preference to the terms “voltage control” or “voltage control”.
The term “North polarity” means that a magnet assembly has magnet(s) with a North pole oriented toward a subject. The term “positive current” means the current direction through a coil which produces an electromagnetic field with North polarity oriented toward a subject.
Example embodiments describe a pulsed electromagnetic field device configured to apply a fluctuating electromagnetic field to a subject organism. The devices have at least one flux module comprising a permanent magnet assembly with at least one permanent magnet, and a coil assembly comprising at least one first configured in proximity to the permanent magnet assembly. A first coil controller is configured to intermittently apply current from a power supply to a first coil.
Some embodiments have a plurality of parallel cylindrical magnets where the first coil is wound around the permanent magnet assembly and configured perpendicular to the longitudinal axes of the magnets.
The devices are held or supported near or against a subject organism, such as a human, animal, or plant. In one example, the pulse controller delivers a plurality of positive and negative current pulses with rise times less than 5 microseconds to generate magnetic filed flux and to induce voltage within the organism.
The single coil 310 is wound symmetrically about an axis parallel to the longitudinal axis of the magnet assembly, and extends around a substantial length of the magnet assembly. In other examples, the coil orientation may be asymmetric to the magnet assembly, the coil may be the same width as, or shorter than, the magnet assembly, or overhang the magnet assembly in one or both directions as indicated by coil sections 311a and 311b. The coil width to diameter aspect ratio may be substantially more or less than shown.
The permanent magnet assembly provides a permanent magnetic field M+ in the direction of tissue (not shown). In this specification, M+ is designated as being directed from the North pole of the magnet assembly. In some configurations, the coil leads (not shown) are introduced at the South pole end of the device. In other configurations, the coil leads are introduced in a manner that does not obstruct either pole region of the magnet assembly, and the device may be used with either the North polarity M+, or the South polarity M−, field lines directed toward tissue. The latter configuration permits the spaced apart placement of two or more devices in various opposing or attracting polarity orientations as discussed below.
In one example, the coil has approximately 200 turns of 26 gauge insulated wire. In other examples, the number of turns may be less, or substantially higher, and various wire size may be used. This example coil configuration appears to be reasonably “tuned” for various magnet assembly configurations, but is likely to be optimized with further modeling and empirical testing. At least two factors appear to influence coil design. First, there are traditional tradeoffs in all coil-based devices between coil intensity from more coil turns and/or higher coil current, versus the duty cycle and heat buildup in the coil due to wire resistance. Second, the combination of magnet and coils creates an antenna which can be “tuned” to reduce reflected signal and thereby increasing the transmission of coil signal. The reflected signal from inefficient tuning generates heat in the coil control, and increases the energy demand of the device.
The flux module acts as an antenna to transmit the coil electromagnetic field. In order to reduce feedback and increase transmission, it is desirable to “tune” the system as described in references [1, 2]. When the assembly is tuned, less power is wasted on feedback to the controller, and the coil may be energized with less current. In prototype devices, tuning reduced the current from a 12 volt power supply from about 1 amp to less than 0.3 amps, and eliminated heat buildup in the controller. A coil of approximately 200 turns appears to perform well with many N52 NIB permanent magnet assemblies, but is likely to be further optimized.
Since antenna signals can be focused or directed with parabolic or other shaped reflectors, it should be possible to provide rear and/or peripheral shielding with various materials to improve the electromagnetic field transmission. In one example, shielding or reflector elements may be configured as a parabolic antenna positioned behind or around the flux module.
Testing indicates that example assemblies are tuned to provide sufficient intensity and depth of field for good therapeutic results for chronic conditions without cooling of either the coil or the control. Further clinical testing may suggest a need for greater coil intensities to address various conditions, and coil or cooling can be provided with active cooling or static cooling, such as cooling rods.
From one perspective, devices appear to work as an antenna which delivers the coil magnetic field flux substantially deeper into tissue than can be achieved with the coil only.
From another perspective, as suggested by the observed oscillation of small permanent magnets suspended along return magnetic field lines of force, the device appears to “ripple” the permanent magnetic field lines by the coil alternately partially repelling the magnet field lines in the direction of C1 when coil and magnet polarity is matched, and partially attracting the magnet field lines in the direction of C2 when the coil and magnet polarity is opposed. This perspective suggests that the coil would be effective with a sequence of only positive or negative current pulses.
It is not practical in medium intensity PEMF devices to provide a large enough coil or enough current to produce a constant magnetic field to match the strength of a strong permanent magnet field. Likewise, it is not practical to create pulses of that strength without accumulating energy to discharge into stronger pulses. Impulse devices use capacitors to provide short pulses that can match or exceed the permanent magnet field, but practical devices cannot be recharged to peak intensity at a rate much greater than a few pulses per second.
Various embodiments of flux modules deliver an increased magnetic flux deeper into tissue that prior art medium intensity PEMF devices. Embodiments have been successfully tested at 900 pulses per second without the need for supplemental coil or controller heat removal, and higher frequencies are likely to be feasible with additional optimization such as faster pulse rise times, shorter pulses, or heat removal.
High intensity impulse PEMF devices can be adapted to incorporate permanent magnet assemblies in order to deliver greater magnetic field flux at higher pulse frequencies (and therefore shorter treatment session times) than can be provided by coils alone.
To date, prototype devices have used the strong N52 NIB magnets, approximately 200 turn coils, and a coil current that can be applied to achieve relatively long pulse duration and relatively high pulse frequency without producing significant heat build-up. Prototype devices have shown unexpected beneficial results for a number of chronic conditions, so development has been directed to improving pulse control, reducing pulse rise times, and designing portable devices. Future research will test various other magnet and coil sizes and configurations, conduct finite element analysis and otherwise characterize and optimize design and control parameters. It may be also be desirable, in some cases, to use stronger permanent magnets as they become available, or weaker permanent magnets.
In other examples, one or more magnets may be used in the magnet assembly, the magnets may have the same dimensions and strengths, different dimensions, different strengths, and symmetric or asymmetric configurations relative to circular or other layouts. In other examples, the magnet assembly comprises one or more permanent magnet of various shapes and sizes in symmetric or asymmetric alignment, and similar or various magnetic strengths. These examples describe various sizes and orientations of cylindrical or ring magnets. Other magnet shapes, such as bar magnets may be used to achieve different magnetic field characteristics. Magnets within a magnet assembly typically have the same polarity alignment. Other polarity alignments could be used to modify magnetic field profiles.
In other examples, the magnet assembly comprises a central cylindrical ring magnet oriented within the hole of a ring magnet.
A magnetic strength calculator [REF 3] demonstrates the effect of magnet shape and dimensions on peak intensity and intensity at distance from the head. Without being limited by theory, applicants suggest that these calculated differences are due, in part, to the relative number of “shortcut” magnetic field lines of force between the poles. This suggests that magnetic field intensity at a distance might be increased with various arrangements of multiple smaller magnets rather than a single larger diameter magnet. The use of smaller magnets also reduces device weight and cost.
Controls may be provided to select pre-programmed pulse protocols, or to select one or more of pulse intensity, pulse frequency, pulse duration, pulse pattern, or session timing. Prior art has suggested that organisms may adapt to constant frequencies, and that it may be desirable to randomly or otherwise vary the coil frequency and/or coil intensity. For reasons described below, prototype devices were simplified.
Measurements of induced voltage from flux modules are substantially greater than the induced voltage from the coil only. In one example, the difference ranged from about 40% at close range to about 25% at distances of a few centimeters.
Over 30 prototype Permaflux devices have been built with various N52 NIB magnet sizes and configurations, and approximately 200 turn coils with 0.3 amp pulse width modified current at 50 Hz with 9 positive and 9 negative current fast-rise pulses per cycle. The device is typically held against or near the skin or head for two minutes per site. Significant beneficial results have been reported for both in-clinic and at-home device use for a number of chronic conditions including pain and inflammation.
Devices used in two minute sessions appear to provide more effective symptom and/or substantive relief than 20-30 minute TMS treatments for a variety of chronic conditions. These results suggest the importance of an overall “dosage” parameter that incorporates the number of pulse events, the intensity of the events, and the effective reach of those events relative to a target region in the body or brain.
In another embodiment, a plurality of flux modules are provided in order to induce voltages over a larger area or volume. As examples, a plurality of flux modules may be affixed to a helmet, headband, belt, vest, or sling support; or provided in a paddle, mat, or mattress housing to deliver flux over a larger area. While magnets having a length to diameter aspect ratio of 2.5 to 5 or more appear to be desirable to improve magnetic field intensity at increased distances from the flux module, larger applicators can employ lower aspect ratio magnets.
The AC powered examples described above have a coil control circuit board that is small enough to be incorporated in a hand-held portable device. In one example, three lithium ion rechargeable batteries, can provide a total voltage of over 11 amps with a battery life that can support many treatment sessions before recharge.
Pods are portable flux modules incorporating smaller power supplies that can be quickly recharged with direct or induction recharged for a few treatments.
Prototype devices were designed, at clinic request, for simplicity of operation, with only an on/off switch. Therapy sessions were timed, and the device could be either held against the subject for maximum intensity, or could be spaced away from the subject by up to a centimeter to reduce intensity by about half.
There are several advantages to this approach relative to more complex programming or control options, including consistency of operation, ease of administration or supervision, and lower patient intimidation.
In one example of a home use treatment protocol for a particular ailment, a medical provider can specify device location, device contact or spacing, and treatment session times and frequency. Since the device price is very low compared to clinical devices, the device can be sold, rented, or borrowed for home use; and home use sessions can be monitored by medical staff by a simple video link such as ZOOM™ or FACETIME™.
By reducing the need for study participants to travel to a supervised test site, video monitoring can also dramatically reduce administration costs and increase feasible participant sample size for controlled studies of device effectiveness for various ailments.
In other examples, the device may include a communications link which permits remote programming of pulse control parameters and session timing.
Operating devices at 900 pulses per second appears to be particularly effective at addressing pain and chronic inflammation, and in strengthening immune response. Other higher or lower pulse rates are also likely to be effective.
In other examples, a second coil is provided, and is operated at a higher targeted frequency than the first coil. In one example, the second coil can be operated a constant frequency in the range of 2000-5000 Hz. Literature suggests that frequencies as high as 1.6 megaHz may be effective. A dual coil device provides two base frequencies as well as sums and differences of the base frequency harmonics. In other examples, the second coil can be operated a variable frequencies. Limited in vitro testing suggests the dual coil device operating at a specific target frequency may be effective in killing or weakening pathogens.
Dual Heads with Attractive or Repulsive Orientations
Despite the significant drop in field intensity with distance from the head, the testing of single devices has shown effectiveness for a wide range of ailments.
In some cases, it may be desirable to provide a more intense and focused magnetic field over a longer distance. The potential effectiveness of using spaced-apart dual flux modules with attracting or opposing heads can be demonstrated with a chamber having iron filings suspended in a viscous liquid. When a first flux module is placed on opposite sides of a chamber several inches from a second flux module having opposite polarity, a horizontal column of filings is suspended between the modules—indicating a strong and near-uniform magnetic field. This type of dual device placement can provide a strong and focused field across a head, torso, leg, or arm.
In other cases, two or more same-polarity devices may be positioned to create repulsive interference regions. Various devices can be positioned to generate a desired magnetic field interference boundary location and shape; and to move that boundary back and forth relative to a desired region of interest.
These types of opposed or attractive polarity configurations may also serve as antennae when a coil is provided with at least one of the magnet assemblies.
The flux module approach shifts the intensity versus distance curve for low to medium intensity PEMF devices toward greater intensity at a given distance from the coil. Since these devices can operate at any pulse frequency, the primary benefit is in improving effective magnetic flux at distance from head.
In some examples, it may be desirable to provide flux modules with much higher coil current than can be supplied without a voltage multiplier. Prior art impulse devices can only provide peak intensity at low pulse rates. For example, an impulse PEMF vendor reported 2020 data showing a peak intensity of 1400 Gauss at 0.54 pulses per second; but dropping to 350 Gauss at 6 pulses per second and to 220 Gauss at 10 pulses per second.
The flux module approach of combining a magnet assembly with high intensity coils in impulse PEMF devices can provide greater intensity, more frequent pulses, or both.
For a given intensity at or below peak, a flux module approach could enable a higher pulse rate, so that treatment times could be reduced by a factor of 2-3× or more. In other cases, such as pelvic muscle contraction, TMS, or migraine therapy, where slow pulse rates may be preferred, a flux module approach —particularly in a dual head opposed polarity configuration—could substantially reduce the required coil size or coil current to match or exceed coil-only performance.
Based on initial clinic use, home use, and device measurements, the embodiments described herein appear to be more effective than prior art PEMF devices in addressing a variety of acute and chronic ailments. The devices appear to be particularly effective in reducing inflammation so that the body's immune system can address those ailments. Many of the applications of PEMF are summarized in U.S. Pat. No. 8,376,925 to Dennis et al. and that list is substantially repeated in the attached claims.
While these embodiments have been described with emphasis on the embodiments, it should be understood that within the scope of the appended claims, the embodiments might be practiced other than as specifically described herein. In particular various configurations of coil assemblies, magnet assemblies, and pulse intensities, pulse duration, pulse rise times, treatment protocols, and device placement may be used.
This is a US National Stage application of PCT application PCT/US21/21295, published as WO 2021/183410, which claims priority from U.S. Provisional Patent Application No. 62/986,758 filed on Mar. 8, 2020.
Filing Document | Filing Date | Country | Kind |
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PCT/US21/21295 | 3/8/2021 | WO |
Number | Date | Country | |
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62986758 | Mar 2020 | US |