Abstract:
A method of increasing bone mass throughout the body of a user. The method may include the steps of obtaining a distributor comprising a plurality of electromagnetic coils, obtaining a controller comprising a processor and a memory device, operably connected to one another, the memory device storing code executable by the processor, selecting a source of electrical current, connecting the source to the controller, and positioning a user proximate the distributor. The method may further include controlling, by the controller in accordance with the code, delivery of electrical current sequentially and exclusively to each coil of the plurality of electromagnetic coils to generate a magnetic field extending into the user.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 11/946,042, filed Nov. 27, 2007, which claims the benefit of co-pending U.S. Provisional Patent Application Ser. No. 60/867,424 filed Nov. 28, 2006, which is incorporated by reference herein. 
     
    
     BACKGROUND 
       [0002]    1. The Field of the Invention 
         [0003]    This invention relates to electromagnetic simulation of bone stress, and more particularly to methods and apparatus to stimulate or otherwise induce electrical activity in bones of a subject in order to elicit a positive response such as natural generation of increased bone density. 
         [0004]    2. The Background Art 
         [0005]    Human tissues are electrical apparatus. Likewise animal tissues are electrical apparatus. A complex assembly of structure, chemistry, and electrical connection controls and implements the activity, growth, healing, and other functions of living tissues of the animal kingdom. Manipulating the structures of tissues, whether soft tissue or bone tissue has been purview of the surgical portion of the medical community. Manipulation of chemistry has been the purview the drug portion of the medical community. Manipulation of the electrical activities of body tissues has largely been left to the other two fields, surgical and chemical treatments. 
         [0006]    There has been a development of an electrical treatment community in the medical field, particularly, dealing with electro-stimulation. However, many researchers in the field often claim a lack of understanding of the specific phenomena that affect the correlation between electrical stimulation and organic functioning of live animal tissues. Nevertheless, electrical stimulation therapy has been used in both invasive and noninvasive systems for directly applying electrical potential to stimulate a response. 
         [0007]    Within the medical community, selected, time-varying electric and magnetic fields have played an increasingly successful role in the care of several challenging medical problems, mainly fractures that have failed to heal, in both children and adults, as well as chronic skin wounds. This progress has been made over the past decades. 
         [0008]    Bioelectromagnetics is a term applied to a field developing in the biological sciences and devoted to the interaction between living organisms and electro-magnetic fields. Electrical phenomenon are inherent in most living organisms, and certainly in all animal organisms. For example bones, nerves, cartilage, muscle, and the like have been considered to contain electrical connections and circuits for their normal operation. Accordingly, these electrical circuits can be influenced by external magnetic fields and electromagnetic fields. Publications indicate that electromagnetic fields operating at frequencies below 300 hertz can influence biological functions. Some controversy exists regarding the mechanics of operation of these interactions. 
         [0009]    Pulsed electromagnetic fields in medicine are not new. Static magnets and electrical current have been used for years. In modern medicine however, it was in about the 1970&#39;s that the United States FDA approved a pulsed electromagnetic field device to assist in the healing of non-union fractures. Doctor C. A. L. Basset pioneered work leading to an 80% success rate in the healing of non-union fractures without any side effects. Accordingly, therapy by pulsed electromagnetic fields is recognized as effective in bone healing in the medical profession. 
         [0010]    Meanwhile, additional detailed work has been done on a cellular level in vitro and in vivo to evaluate the efficacy of pulsed electromagnetic fields on bone density. Much of the work seems to be devoted to establishing a specific biological mechanisms by which electromagnetic fields couple to body chemistry and cellular activity. 
         [0011]    With the magnetic fields induced by an MRI machine, molecular dipoles orient along the magnetic field lines. Once the magnetic field is collapsed, the dipoles, actual physical molecules, rotate back to their original positions. The return to the original positions generates another magnetic pulse, which pulse is detected and used to reconstruct in a computer an image of the tissues within the MRI field. 
         [0012]    Thus, electromagnetic fields are not only known to affect body tissues, but body tissues themselves generate magnetic fields by their own motion, which magnetic fields are sufficiently strong to be detected and analyzed by sophisticated signal processing in order to image tissues and boundaries of tissues in the body. 
         [0013]    Likewise, the bone structures of a body are known to have a piezoelectric characteristic. That is, they respond to stress by creating an electrical potential. Likewise, however, since piezoelectric events are symmetric. The application of electrical potential will then cause stress. 
         [0014]    What is needed is a system implementing a method and apparatus for coupling, non-invasively, an external electromagnetic field to the body tissues that may provide electrical stimulation to bones. 
         [0015]    It would be an advance in the art to improve non-invasive electro-stimulation by magnetic coupling of an electrical system outside of a subject with the electrical system within a subject. 
       BRIEF SUMMARY OF THE INVENTION 
       [0016]    In view of the foregoing, in accordance with the invention as embodied and broadly described herein, a method and apparatus are disclosed in one embodiment of the present invention as including a distributor comprising a plurality of electromagnetic coils. A controller may control the operation of the distributor. The controller may include a processor and a memory device operably connected to one another, the memory device storing code executable by the processor. The controller may be connected to a source of electrical current. During operation, a user may be positioned proximate the distributor (e.g., recline or lie over or below the distributor). The controller may then control, according to the code, delivery of electrical current to the coils. In one embodiment, the controller may deliver current sequentially and exclusively to each coil to generate a magnetic field extending into the user. 
         [0017]    In accordance with the foregoing, an apparatus and method in accordance with the invention implement a magnetic coil providing a magnetic field penetrating a depth into a body sufficient to provide the designated field strength near a bone thereof. Accordingly, in an apparatus and method in accordance with the invention, the magnetic field acts in several ways. 
         [0018]    First, as the field is established, and as it collapses, it is effectively capable of inducing currents in circuits within the field. That is, whenever a circuit moves through a magnetic field, or a magnetic field moves across a circuit current is induced in the circuit. Thus, electrical circuits within the magnetic field generated by an apparatus will obey the law of physics and generate currents. Whether a circuit is formed of wire or of animal tissues, relative motion between the circuit and the magnetic field will generate electrical currents in the circuit. 
         [0019]    Second, by generating a magnetic field, certain molecular dipoles in cells within the body will undergo alignment or a tendency to align with the field lines of the applied magnetic field. This provides an actual mechanical displacement stimulation. 
         [0020]    Third, any generation of an electrical potential across a piezoelectric element causes stress and typically strains at a “micro” level. This stress and strain is not distinguishable from “macro” level stresses and strains corresponding to exercise. 
         [0021]    Applicants observed in the use of electromagnetic stimulation for bone healing of fractures in persons having poor bone repair function (e.g., smokers, diabetics, poor circulation subjects, etc.) that electromagnetic stimulation aided both fracture healing and joinder of fused constituents. However, following treatments effective to aid the bone healing, it was observed that even on the gross scale provided by X-ray images, an increase in bone density was apparent. Thus, Applicants engineered a system to augment bone density increase over the entire body. Applying a local electromagnetic field to one location of the body is not scalable by simply adding more devices, to treat the entire body with a mechanism of electromagnetic therapy. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    The foregoing features of the present invention will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only typical embodiments of the invention and are, therefore, not to be considered limiting of its scope, the invention will be described with additional specificity and detail through use of the accompanying drawings in which: 
           [0023]      FIG. 1  is a schematic diagram of an apparatus in accordance with the invention; 
           [0024]      FIG. 2  is a schematic top plan view of a coil in the apparatus of  FIG. 1 ; 
           [0025]      FIG. 3  is an end view of the coil of  FIG. 2 ; 
           [0026]      FIG. 4  is a plan view of one embodiment of the distributor portion of the apparatus of  FIG. 1 ; 
           [0027]      FIG. 5  is a schematic block diagram of one embodiment of a method in accordance with the invention in a very simplified form; 
           [0028]      FIG. 6  is a diagram of a side elevation view of the distributor of  FIG. 4  illustrating application of current and thus magnetic field as applied to each coil in sequence in accordance with the invention; 
           [0029]      FIG. 7  is a schematic block diagram of a method in accordance with the invention for controlling treatment and recording therapy session data; 
           [0030]      FIG. 8  is a schematic block diagram of a more sophisticated process in accordance with the invention identifying various decisions and options as well as the effect of sensing as a means to control operation of an apparatus in accordance with the present invention; 
           [0031]      FIG. 9  is a diagram of top plan view of a sensor-equipped distributor with coils of various alternative configurations; and 
           [0032]      FIG. 10  illustrates one example of an embodiment of a distributor of an apparatus in accordance with the invention, illustrating one implementation for a double bed cover, blanket, mattress-cover, or the like. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0033]    It will be readily understood that the components of the present invention, as generally described and illustrated in the drawings herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the system and methods of the present invention, as represented in the drawings, is not intended to limit the scope of the invention, as claimed, but is merely representative of various embodiments of the invention. The illustrated embodiments of the invention will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. 
         [0034]    Referring to  FIG. 1 , an apparatus  10  in accordance with the invention may include a distributor  12  effective to distribute electromagnetic flux through a subject or user. The distributor  12  may be controlled by a controller  14 . The controller  14  may control current, duration, frequency, and the like for the electromagnetic flux provided by the distributor  12  to a subject. 
         [0035]    A power supply  16  may provide conditioned power to the controller  14 . The power supply  16  may be adapted to receive electric power from a power source  18  such as conventional wall current, multi-phase current available on distribution in a building, a generator, or the like. In selected embodiments, a power supply  16  may convert alternating current (AC) received from the power source  18  into low voltage DC power suitable for operating the controller  14 . A power supply  16  may also condition power to be provided to the distributor  12 . 
         [0036]    In certain embodiments, a distributor  12  may include multiple coils  20   a ,  20   b ,  20   c , each formed of several turns of an electrical conductor. When energized with current, each coil  20  may become an electromagnetic coil creating an electromagnetic field. A distributor  12  in accordance with the present invention may also include one or more feedback devices  22 . 
         [0037]    A feedback device  22  may provide information assisting the controller  14  in controlling the distributor  12 . For example, various types of feedback devices  22  may be implemented including human actuated controls, detectors for detecting the presence of a user, temperature sensors, current sensors, or the like. In selected embodiments, the feedback devices  22  may insure safety, proper operation, limit duty cycles, and so forth. 
         [0038]    In addition to controller feedback devices  22 , a distributor  12  may include user feedback devices  24 . A user feedback device  24  may provide confirmation to the user that the apparatus or distributor  10  is functioning properly. That is, a user without additional aids may be unable to perceive the electromagnetic field or fields being generated by a system  10  in accordance with the present invention. Accordingly, a system  10  may include one or more feedback devices  24  providing visual confirmation of activity. Such devices  24  may include light-emitting diodes (LEDs), displays, lights, or the like to encourage or sustain a user in his or her use of the system  10 . 
         [0039]    In selected embodiments, a controller  14  may include a processor  26  operably connected to a memory device  28 . A memory device  28  may store the applications, programs, or code executed by the processor  26  during operation of the system  10 . In selected embodiments, a processor  26  and memory device  28  may collectively be embodied as a microprocessor. 
         [0040]    In certain embodiments, a controller  14  may include a user interface  30  receiving inputs from a user. For example, certain interfaces  30  may include keypads, switches, knobs, buttons, touch screens, monitors, or other mechanisms for interaction with a user in generating electrical signals to be received by a processor  26 . Accordingly, a user may enter program parameters, timing information, duration information, frequency control information, current information, or the like and thereby influence or control operation of the distributor  12 . Likewise, a user may select a particular intensity of electromagnetic field, frequency thereof, or the like. Alternatively, certain parameters may be “hardwired” into a controller  14  while others may be controlled through a user interface  30 . 
         [0041]    In selected embodiments, a user interface  30  may accept inputs that are more qualitative then quantitative to a user. Such inputs may be translated by a processor  26  into specific engineering and physics terms or variables suitable for implementation. For example, a user may input selection of a long or short session. A user may input a request for a weak, medium, or strong intensity, and the like. Accordingly, preselected ranges may be programmed into the processor  26  in order to comply with the user&#39;s qualitative requirements with quantitative data that will be used by the processor  26  when controlling the distributor  12 . 
         [0042]    A user interface  30  in accordance with the present invention may also provide selected feedback or information to a user. For example, a user interface  30  may include one or more displays. In certain embodiments, the operating conditions of a controller  14  may show in a display. The display may show simultaneously, sequentially (e.g., cycle through), or as instructed by a user any or all parameters. Parameters may include repetition frequency, pulse current, duty cycle, magnetic field values, or other parameters of the system  10 . A display may also show treatment progress, time elapsed, time to end of treatment, or the like, and may include audio or other outputs to signal various stages of the session (e.g., the end of the session). 
         [0043]    In selected embodiments, a controller  14  may include one or more control devices  32 . A control device  32  may implement the control functions specified by the processor  26  of the controller  14 . For example, a control device  32  may include control circuitry (e.g., logic, switches, various relays, etc.) translating a control signal from the processor  26  into an actual current delivered to a specific coil  20  of the distributor  12 . 
         [0044]    A controller  14 , through a processor  26 , may dictate the current waveforms supplied to the coils  20  of a distributor  12 . Parameters dictated by a controller  14  may include pulse repetition frequency, pulse amplitude, duty cycle of pulse current, duration of treatment sessions, or the like. Such parameters may be fixed at the time of manufacture or be selectable by a user or treatment controller (e.g., medical personnel). 
         [0045]    Referring to  FIGS. 2-3 , an apparatus  10  in accordance with the invention may include several coils  20  each having a specified interior width  34  as well as an exterior width  35 . Typically, it is good magnetic design to maintain the interior width  34  as close to the exterior width  35  as possible. Nevertheless, to be more comfortable for a user, it may be preferable to distribute wires or cables further apart in order to avoid a sensation or feel of too much weight or stiffness in a particular area of the distributor  12 . 
         [0046]    Likewise, the coils  20  may each have an interior length  36  as well as an exterior length  37 . The interior width  34  and interior length  36  may establish a flux window through which the magnetic flux of the coil  20  passes. The dimensions  34 ,  35 ,  36 ,  37  of the coil  20 , as well as the number of turns  38  of the coil  20 , may be used to control the magnetic strength of flux generated by the coil  20 . The current passing through the turns  38  of the coil  20  may also provide a degree of control over the magnetic flux. 
         [0047]    Accordingly, a window  40  or aperture  40  may represent the area filled with the flux of the magnetic field generated by current through the turns  38  of the coil  20 . In general, the coil  20  will extend in a longitudinal direction  42  and the lateral direction  44 , corresponding, typically, to the width  34  and the length  36 , respectively. Thus the flux through the aperture  40  or window  40  passes in the transverse direction  46  through the window  40 . 
         [0048]    As can be determined by the directional arrows  42 ,  44 ,  46 , the illustration of  FIG. 3  represents an end view of the coil  20  of  FIG. 2 . Thus, the direction of current flowing through the coil  20  or through the turns  38  of the coil  20  is illustrated by the arrow  48 . The direction  48  of current controls, according to the respective laws of physics, the direction of the magnetic field  50  passing through the window  40 . 
         [0049]    Meanwhile, the depth  52  of the magnetic field  50  may characterize the strength of a field  50  at a certain distance from the coil  20 . That is, for example, the earth has a magnetic field that extends from pole to pole and extends out through a large volume of space. Similarly, the coil  20  has the ability to create flux lines  50  that extend far away. Nevertheless, at greater distances  52 , the intensity or strength of the flux  50  may be less. 
         [0050]    For example, near the actual wires forming the turns  38  of the coil  20 , a very tightly turned flux  50  may be generated. Meanwhile, near the center of the coil  20 , the flux lines may be substantially perpendicular or “normal” to the plane of the coil  20 . While lines of flux  50  near the turns  38  themselves may close in a comparatively “tight” loop, the lines of flux  50  nearer to the center may extend a far distance before they eventually turn back and enclose on themselves in a loop. Necessarily, the flux density out in that large expanse of space may be commensurately small. 
         [0051]    By contrast, the flux density within the window  40  containing the same amount of flux will be comparatively higher. Thus, the width  34  and length  36  of a coil  20  may create a flux distribution of a desired intensity within the window  40  and a desired intensity at a distance  52  corresponding to the depth of a human body. 
         [0052]    Referring to  FIG. 4 , in certain embodiments, when treatment is commenced, repetitive current pulses may be transferred (e.g., through cabling) to a distributor  12 . A distributor  12  may include one or more coils  20 , typically one to six. The coils  20  may cover a significant portion of the distributor. For example, in selected embodiments, coils  20  may consume about 60% to about 90% of the surface area of the distributor  12 . 
         [0053]    In certain embodiments, the coils  20  may be connected in series. When so connected, the overall effect is that the pulse current circulates unidirectionally around the periphery of the array of coils  20 . This ensures that a patient or user will experience at least a minimum value of the electromagnetic field, typically about 25% to about 30% of the maximum field produced in the middle of the user&#39;s body. Alternatively, coils  20  may be divided into sets of one or more, with each set being sequentially pulsed. This may avoid the partial field cancellation that may otherwise occur when coils  20  (or the electromagnetic fields produced by the coils  20 ) overlap. 
         [0054]    In selected embodiments, each cycle of the current waveform may include an equal number of current pulses in each directions. This may permit a distributor  12  to be positioned easily, without any preferred or required orientation. Additionally, if any area of the body is more responsive to an electromagnetic field in one direction more than in the other, that area will receive adequate stimulation. 
         [0055]    In one embodiment of an apparatus  10  in accordance with the invention, a distributor  12  may be formed as an article of bedding. For example, a distributor  12  may comprise a matrix  54  of fabric or similar materials suitable for use as a blanket, mattress cover, layer within a mattress, or the like. The matrix  54  may provide a soft feel, warmth, or other sensory and tactile features desired by a user. 
         [0056]    In selected embodiments, a matrix  54  may connect, stabilize, and secure the various coils  20   a ,  20   b ,  20   c ,  20   d ,  20   e . Since electromagnetic flux  50  can directly interfere with and cancel other electromagnetic flux, two conditions may be maintained with respect to the coils  20 . First, the coils  20  may be set in a non-overlapping arrangement in space. For example, the coils  20  may be positioned so as to be substantially coplanar (e.g., distributed in a longitudinal direction  42  along the matrix  54 ). Second, the coils  20  may be activated in a non-overlapping arrangement in time. That is, in selected embodiments, the controller  14  may ensure that no coil  20  is building, sustaining, or collapsing an electromagnetic field  50  at the same time that another coil  20  is building, sustaining, or collapsing an electromagnetic field  50 . Thus, there is no interference between the coils  20  and no negation of the effectiveness thereof. 
         [0057]    As a practical matter, the sequencing of energy delivery or current delivery to each of the coils  20   a ,  20   b ,  20   c ,  20   d ,  20   e  may be in any suitable sequence. For example, a strict sequential alternating between coils or from one coil to the next, adjacent coil may be appropriate. Likewise, a completely random distribution or sequencing between coils  20  may be acceptable and provided by the controller  14 . 
         [0058]    Moreover, since the strength of an electromagnetic field  50  may be dependent upon the electrical current and the number of turns  38  in a coil  20 , electrical heating may occur if the duty cycle for a coil  20  is too high. It has been found that a duty cycle in the range of from about 2% to about 10% is adequate. With variations in current, the duty cycle may be manipulated. That is, for example, with a lower current the same magnetic flux may be obtained with more turns  38  in a coil  20 . Thus, the dynamic flux  50  desired through the aperture  40  of a coil  20  may be designed to control the heat losses and the appropriate duty cycle for the apparatus  10 , and for the individual coils  20 . 
         [0059]    Referring to  FIGS. 5 and 6 , one approach to sequencing the current through the individual coils  20  may be to rely on a process  60  dictated by the controller  14 . For example, upon starting  62 , the process  60  may apply  64  power to the system  10 . Thereafter, inputs may be received  66  by the system  10 . Such inputs may include any parameters used by the processor  26  in controlling operation of the coils  20  (e.g., times, durations, intensities, frequencies, currents, or other similar values on a quantitative, qualitative, or comparable basis). 
         [0060]    In accordance with the input received  66  or other pre-set instructions or code, the controller  14  may apply  68  current to a particular coil  20 . After a preselected time, or a calculated time based on other parameters such a flux density, current, and time, or the like, the controller  14  may dictate removal  72  (termination) of the current from the coil  20 . 
         [0061]    Next, the controller  14  may advance  74  to the next coil  20  in the sequence. The controller  14  may then return  70  to application  68  of current to a coil  20 , followed by a removal  72  of the current and advancing  74  to the next coil  20 . The cycle of applying current  68 , removing  72  current, and then advancing  74  to the next coil  20  may continue for some period of time (e.g., a session duration), in accordance with an appropriate duty cycle. 
         [0062]    A duty cycle that is too great for a power supply  16  or for a coil  20  may cause failure of the power supply  16  or overheating of the coils  20 . Accordingly, power may be removed  76  from the system  10  between activation of individual coils  20  for some extended period of time in order to enforce a duty cycle. Alternatively, power may be removed  76  from the system after cycling through all the coils  20  within the distributor  12 . In yet another alternative embodiment, power may be removed  76  from the system  10  after a preselected or sensed number of cycles of applying  68  and removing  72  current from the coils  20 . 
         [0063]    The end  78  of a treatment session may be controlled by time, or by a net effective dosage of electromagnetic fields  50 . For example, a user may have an exposure to higher field strength of flux  50  for a lower time or have an exposure to a lower strength of flux  50  for a greater amount of time. In certain embodiments, the field  50  or the flux density  50  and field strength may not be changeable by user, and the time may be fixed at some appropriate amount of time (e.g., one to three hours). In other embodiments, these parameters may all be changed and exchanged in order to approach the therapy desired. 
         [0064]    Referring to  FIG. 6 , a sequence  80  illustrates the generation of magnetic flux  50  consequent to applying current  68  to each coil  20  in sequence. Accordingly, during a first time period, an electromagnetic field  50  may be generated from one coil  20   a . In a subsequent time period, an electromagnetic field  50  may be generated from another coil  20   b . In yet other subsequent time periods, electromagnetic fields  50  may be generated sequentially or in turn from the remaining coils  20   c ,  20   d , and  20   e . Thus,  FIG. 6  illustrates the application  68  of current to a coil  20 , followed by removal  72  thereof and advancing  74  to the next loop  20 . 
         [0065]    Referring to  FIG. 7 , an alternative method  60  in accordance with the invention may include additional optional steps with respect to the basic process  60  of  FIG. 5 . For example, after application  64  of power to the system  10 , receipt  66  of inputs thereto, application  68  of current to a coil  20 , and removal  72  thereof, the return  70  may include additional steps. A decision  82  may be made as to whether continued treatment is to be implemented. This may be accomplished in any suitable manner. 
         [0066]    For example, in one embodiment, a controller  14  may include a timer establishing a therapy duration. The controller  14  may enforce that duration by any mechanical, electrical, or electro-mechanical timer that will shut off current to the coils  20  after a specified duration. For example, a time period from about half an hour to about three hours may be an adequate duration. Times up to ten hours may be effective. Nevertheless, for the use in stabilizing or reversing osteoporosis, between one and a half and two and a half hours may be a suitable duration. 
         [0067]    Thus, at the end of a predetermined duration or by any other suitable parameter, the decision  82  may be made to continue or discontinue the present treatment session. If treatment is to be continued, an affirmative answer may result in advancement  74  to the next coil  20 . Alternatively, an affirmative answer may lead to an additional decision  84  as to whether a cycle of all the coils  20  within a distributor  12  has been completed. If a cycle of all the coils  20  has not been completed, then an advance  74  may occur, returning to the application  68  of current to the next coil  20  in the sequence. Alternatively, if the cycle has been completed, then a change  86  in the direction of current may be applied. 
         [0068]    Certain molecules in the cells of the body are dipoles. They act as small bar magnets rotating to align with a magnetic field  50 . Accordingly, it may be beneficial to change  86  the direction of current and thus reverse the polarity of the magnetic field  50  induced by the various coils  20 . A change  86  in the direction of the current applied to a coil  20  may be done on every alternate cycle, or after a number of cycles. For example, the direction of current may be changed with each cycle, or with every five cycles, every ten cycles, etc. as determined to be most beneficial. Alternatively, each application  68  of current to a coil  20  may include application of current in both directions (e.g., one followed by the other). 
         [0069]    For example, current may be applied  68  at a step function  85 , “on” followed by “off” followed by “on.” The direction of the current may then be changed  86  and the step function  85  may continue. Alternatively, the current may be applied  68  in an alternating manner (e.g., in a sinusoidal pattern  87 ) where the current transitions from a maximum peak in one direction to zero to a maximum peak in the opposite direction. When the current is applied  68  in such an alternating manner, there may be no need to determine  84  whether a cycle has been completed, and the process  60  may simply advance  74  to the next coil  20 . 
         [0070]    When the decision  82  of whether a treatment session should be continued is answered in the negative, application  68  of current to the coils  20  may cease. If desired, certain data characterizing the treatment session may be recorded  88 , output  90 , or both. In one embodiment, recording  88  the treatment session data may include recording user identification, session duration, current or magnetic field strength, waveform characteristics, or the like. 
         [0071]    Such data may assist in determining effectiveness of treatment and monitoring whether the prescribed treatment has been completed. Output  90  of session data may be provided to a centralized computer, printed, or simply displayed so that it may be logged by user patient. Accordingly, information characterizing a treatment session may be used for more general parametric evaluation of the efficacy of treatments over a broad population of patients. Finally, removal  76  of power from the system  10  or disconnection  76  of power from the system  10  results in an end  78  of the treatment. 
         [0072]    Referring to  FIG. 8 , in various applications of medical treatments or other therapies, patient compliance is often a concern. Patient compliance may be limited due to memory issues, confusion, fatigue, or the like. Thus, everything from aptitude to attitude may affect the efficacy or the administration of any treatment. 
         [0073]    Accordingly, a method  60  in accordance with the invention may provide for certain user-system interactivity that may aid in compliance. For example, in selected embodiments, a process  60  may include detecting  92  whether a user is present. This may be accomplished by implementation of a sensor of any several types. In one embodiment, a distributor  12  may be installed on a bed as a mattress or mattress cover. 
         [0074]    The distributor  12  may include one or more sensors using capacitance, contact, inductance, or the like to detect the presence of a user. A simple pressure contact or capacitance change sensor may detect  92  the presence of a user lying on the bed. When that presence is detected  92 , the apparatus  10  may proceed to apply current to the coils  20 . 
         [0075]    By contrast, if a user is not detected  92 , the apparatus  10  may enter  94  a holding pattern and wait unit a user is present (e.g., enter  94  a pattern of periodically polling one or more sensors to determine whether a user is present). 
         [0076]    In some embodiments, a controller  14  may utilize an algorithm to determine  92  whether a user is present in a manner suitable for treatment. For example, a user sitting on a bed to put on a pair of shoes, may not be suited for treatment. Accordingly, in selected embodiments, both a particular time of day or night or a particular duration of presence may be required to move on within the process  60 . Likewise, if a user is seated, it may be that only sensors near one or two coils may be activated. Accordingly, the controller  14  may determine  92  that the user is not present for treatment. Thus, an algorithm may assist in interpreting the various parameter indicating that a user is present, leading to a better decision  92  as to whether treatment should begin or continue. 
         [0077]    In selected embodiments, once the decision  82  has been made to end a treatment session, a system  10  may wait  96  for the next treatment session to begin. The duration of that waiting period  96  may depend upon one or more factors. For example, if a system  10  is dedicated to a particular user (e.g., positioned on the bed of a particular user), the wait  96  may be preprogrammed by a delay time, time of day, or the like. 
         [0078]    For example, a typical user will may undergo a period of therapy perhaps once every evening (or every other evening) shortly after retiring. Accordingly, the wait  96  may begin with the end of one treatment session and end the evening of a later day. At that time, the sensors may be activated, permitting the system  10  to again apply  68  current when it is determined  92  that a user is present. 
         [0079]    Referring to  FIG. 9 , a distributor  12  may include one or more user feedback devices  24 . In certain embodiments, user feedback devices  24  may be embodied as one or more light emitting diodes  98  (LEDs) arranged on a distributor  12 . The LEDs  98  may be configured in any suitable arrangement and be illuminated in any suitable degree, pattern, sequence, or the like. 
         [0080]    For example, in one embodiments, LEDs  98  may be positioned along the borders of a distributor  12 . The LEDs  98  may be illuminated by a controller  14  whenever current is being applied  68  to the coils  20 . Alternatively, certain LEDs  98  may be illuminated whenever to the overall system  10  is powered, while other may be illuminated whenever current is being applied  68  to the coils  20 . In one embodiment, LEDs  98  may illuminate only when the coil  20  most proximate thereto is receiving current. 
         [0081]    In selected embodiments, a distributor  12  may include one or more sensors  100  distributed throughout the matrix  54 . In certain embodiments, the sensors  100  may all be identical. In other embodiments, an array of sensors  100  may include various sensors for different parameters. For example, in selected embodiments, one or more sensors  100  may represent a capacitance detector for pressure. Accordingly, if a user is present, then pressure on one side of a flexible capacitive sensor  100  may decrease capacitance and thereby indicate the presence of a user. 
         [0082]    In other embodiments, one or more sensors  100  may be simple contact sensors that indicate pressure as a digital “yes” or “no” (“on” or “off”) condition. In still other embodiments, one or more sensors  100  may sense temperature, heart rate, inductance, or the like to detect, monitor, or otherwise provide information to the controller  14 . In more sophisticated systems, a pulse, represented by either a repetitive motion or cyclical pressure, or a temperature increase due to the presence of a living person may serve to trigger a sensor  100  to activate the apparatus  10 . 
         [0083]    Meanwhile, the insets illustrate alternative embodiments of the coils  20  in accordance with the invention. For example, the orientation of the coils  20  may be with their long direction extending in the longitudinal direction of the distributor  12 . Likewise, in certain embodiments, the coils  20  may be circular. In other embodiments, the coils  20  may have an aspect ratio closer to one. That is, in certain embodiments, the ratio of width  34  to the length  36  of a coil  20  may approximate a value of unity. In other embodiments, the ratio of the width  34  to the length  36  of a coil  20  may be significantly less then one. 
         [0084]    Referring to  FIG. 10 , an apparatus  10  in accordance with the invention may include a distributor  12  sized to fit a double bed (i.e., double, queen, king, etc.). The matrix  54  may be provided with coils  20  distributed to be separately controllable between two individuals. Accordingly, one array may be aligned with one side of a double bed, whereas another array of coils may be aligned with the other side of the same double bed. 
         [0085]    In a simplified embodiment, both sides may be controlled at the same time. Nevertheless, the embodiment of  FIG. 10  illustrates one reason why individual controls such as those illustrated in  FIGS. 7-8  may efficaciously apply the electromagnetic therapy only when a user is present. 
         [0086]    In one embodiment, an apparatus as illustrated in  FIGS. 1-4  was configured with the matrix being a blanket containing five coils. The interior width of each coil had a value of 18 cm and the interior length had a value of 48 cm. Each coil included ten turns. The field strength at 30 cm from the blanket surface, was controllable or presetable at from about zero to about 100 micro Tesla (uT), for an effective range of from about 1 to about 100 micro Tesla. The duty cycle target was in the range of from about 5% to about 15%, depending on current flow, with a target of about 7%. 
         [0087]    Coils may be connected in series, so long as the direction of current is the same in each, avoiding cancellation. Series connection, or individually activated in sequence, they provided relatively uniform coverage over the dimensions of a whole body covered by the blanket. Field cancellation was largely avoided. In one embodiment, additional coils were added around the periphery of the entire array of the five coils. The overall effect of the peripheral current in the peripheral coil was about one fifth the field strength of the regular coils  20  at 30 cm from the blanket. 
         [0088]    Thus, even a simple series connection of the coils can provide a good coverage of the whole volume of the body with the difference between minimum and maximum exposure generally varying by less that about one third. 
         [0089]    Typically from about five to about twenty turns make a suitable coil, with ten to twelve turns forming a good design target. However, it was found that the turns per coil can realistically be varied from about one to about 100 or even more with proper engineering. The magnetic field produced is directly proportional to the product of current and number of turns, a small number of turns requires a high current, which requires heavy duty circuitry and robust connectors, but a large number of turns has a high resistance and so requires a high voltage and good quality insulation. 
         [0090]    From about 15 to about 60 volts may be preferable for safety, but many countries use 240 volts, while the U.S. uses 115 volts (often characterized as 110 or 120 volt outlet power). For not more than 50 volts, a good compromise is around 10 turns per coil. 
         [0091]    With respect to coil dimensions, the field of a circular coil of diameter D at a distance D normal (perpendicular) to the plane of the coil, the field strength is about 45% of the field at the center of the coil in the plane of the coil. With rectangular coils 60 cm×30 cm, the field strength 30 cm from the center of the coil along its axis of symmetry is slightly above 50% of the field at the center of the coil. Thus dimensions of 60 cm×30 cm are adequate for good field penetration and even distribution to a depth of at least about 40 cm. Coils 50 cm×25 cm are adequate but might be regarded as the smaller end of the size range effective for full body exposure. However, they require proportionately less current for the same field strength exposure. 
         [0092]    In one engineered design, a single peripheral coil of from about 15 to about 40 turns, having a (maximum) pulsed current from about 10 to about 15 amperes provides about the same weight of conductor as a five-coil distributor. Fabrication is simpler, cheaper and field exposure is more uniform. However, user perception has a psychological effect. A user may think (incorrectly) that the absence of coils in the main area of the blanket is a disadvantage. 
         [0093]    High frequencies such as radio frequency (RF) waves produce heating but no known, physio-chemical response in mammalian tissue. However, an apparatus and method in accordance with the invention induces currents in circuits within its fields. Likewise, those currents distribute voltages across all elements of tissue circuits that conduct. Accordingly, all circuits that include bone cells as elements expose that piezoelectric bone to a potential, e.g. voltage, inducing a stress (load force per unit area) and a strain (displacement length per unit length), prompting a response by the organism. The stress, strain, and potential appear to be consistent with exercise, and the physiology of the organism (e.g. person, animal) may respond as if it were. Thus, frequencies of from about 1 Hertz (i.e. low values, single digits or fractions) up to about 100 Hertz may trigger or otherwise couple with such physiological responses. 
         [0094]    In addition, a mammalian body has immune and nervous systems having chemical reactions that generate electrical signals. These may respond repetitively at a communication frequency of from about 10 to about 100 Hertz. On the other hand, a single response may often be triggered by pulses of much shorter duration. Thus, a repetition rate in the range of from about 10 Hertz to about 1000 Hertz may rely on comparatively shorter pulses. 
         [0095]    A duty cycle in the range of 2 to 15% with the above pulse repetition rates may cause a repetitive electro-chemical stimulation in the body simulating use of parts by communicating as much, even without actually loading these tissues. 
         [0096]    For stimulation effect caused by induced potential, the pulse shape may be sharp, i.e. a square or rectangular pulse waveform, or a comparatively short duration sinusoidal waveform at frequencies corresponding to bodily electrical functions. A very much slower rise is not contemplated to be effective for this type of coupling. 
         [0097]    A repetition rate of from about 100 Hertz to about 300 Hertz provides a frequency similar to that of the immune system, relevant body mechanisms, or both, in vigorous exercise. It is contemplated that a duration of from about one half hour to about 2 hours per day. A repetition frequency of 3 to 5 sessions (days of treatment) per week is consistent with exercise rates known to be effective in maintaining general health. 
         [0098]    In one embodiment, a magnetic field of up to 100 uT may be supplied to the bulk of a human body at a pulse repetition rate of from about 50 to about 500 Hz. A duty cycle of over 1% and preferably from about 5% to about 15% may ensure a magnetic pulse long enough for the body electrochemical processes to be stimulated. A rectangular or rapidly rising and falling current pulse shape or waveform from a large, single magnetic coil having from about 5 to about 50 turns extending around a blanket, proximate the perimeter thereof may serve well. Sequencing current delivery to an array of from 1 to about 6 coils, each having from about 5 to about 15 coils, and preferably about 10 turns each may cover the same area. 
         [0099]    A treatment period may operate with power inputs greater than 1 VA, and typically may draw from about 5 to about 10 VA of power. During each cycle, the pulses may be reversed in a manner to provide about an equal number of magnetic pulses in the forward and reverse directions. For this and other reason there need be no requirement for any specific orientation of the blanket. 
         [0100]    The frequency and field range provided by the coils of a distributor, such as one with a blanket or mattress pad acting as a matrix, may be fixed or adjustable by a user or caretaker. It may also be regularly cycled, or timed by calendar or computer clock as to repetition of sessions, or the like. 
         [0101]    The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative, and not restrictive. The scope of the invention is, therefore, indicated by the appended claims, rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.