Abstract:
The invention discloses an electrotherapy device for generating specifically designed low frequency pulsed magnetic fields (Cnp waveforms). The device comprises a memory storing at least one digital Cnp waveform and a digital to analog converter converting the at least one digital Cnp waveform into an analog Cnp waveform for application to a subject. A processor communicates with the memory and is responsive to operator input and conditioning the memory to output the at least one digital Cnp waveform directly to the digital to analog converter thereby to bypass the processor. The electrotherapy device is useful for electrotherapy of a subject to modify a variety of clinical physiological, neurological and behavioural conditions.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates generally to electrotherapy and in particular to a portable electrotherapy device for generating specifically designed low frequency pulsed magnetic fields that are used to modify a variety of clinical physiological, neurological and behavioural conditions in vertebrates and invertebrates.  
       BACKGROUND OF THE INVENTION  
       [0002]     Diverse studies have shown that the behavioural, cellular and physiological functions of animals can be affected by magnetic stimuli. Weak magnetic fields exert a variety of biological effects ranging from alterations in cellular ion flux to modifications of animal orientation and learning, and therapeutic actions in humans.  
         [0003]     There are several theories addressing the mechanism of the effect of low frequency magnetic field exposure on tissues. For example, low frequency magnetic field exposures have been proposed to exert their effect(s) through the induction of electric currents. Weak magnetic fields have also been proposed to be detected by particles of magnetite in tissue and by virtue of this detection, have a physiological effect; however, this magnetite based mechanism is not widely believed (Prato, F. S.; Kavaliers, M.; Carson, J. L. L. (1996) Behavioral evidence that magnetic field effects in the land snail,  Cepaea nemoralis , might not depend on magnetite or induced electric currents. Bioelectromagnetics. 17:123-130.).  
         [0004]     Extremely low frequency (ELF) magnetic fields are a physical agent which have little attenuation in tissue and therefore, can be used to alter endogenous processes provided they can be detected and their detection coupled to a physiological process. It has now been shown that magnetic fields may be designed as time varying signals such that they can be used to alter specific targeted physiological processes and in this manner can be used to treat/modify various neurological and physiological conditions and behaviours. U.S. Pat. No. 6,234,953 to Thomas et al., the contents of which are incorporated herein by reference, discloses such a method of using low frequency magnetic pulses to treat physiological, neurological and behavioural disorders.  
         [0005]     Devices for generating electromagnetic waveforms to stimulate a subject are also known. For example, U.S. Pat. No. 6,312,376 to Koren et al. discloses an apparatus for generating electromagnetic waveforms that includes a signal generator and a selector. The selector applies mathematically-derived waveforms generated by the processor of the signal generator onto selected channels in response to channel select input. The generated waveforms are applied to electromagnetic devices thereby to expose a subject wearing the electromagnetic devices to the generated electromagnetic waveforms. Although this apparatus is satisfactory, improvements are desired.  
         [0006]     PCT Application Publication Number WO 96/11723 to Edwards et al. discloses an electromagnetic therapy device that stores waveform parameters such as pulse width, duration, duty cycles and frequency, execution order, change table and various counters in order to effect implementations of varying sequences of square waveforms. During operation, a microprocessor imports these operational parameters and produces a corresponding sequence of digital values. The digital values, together constituting a square waveform, are then converted into electrical current by a waveform generator and applied to an inductor in order to produce the resultant magnetic fields. The Edwards et al. device requires its microprocessor to execute several instructions in order to generate each digital value in real-time. In doing so, the microprocessor is occupied for several cycles per digital value produced and is accordingly restricted in terms of the frequency at which it can produce those values. As a result, Edward&#39;s device is inherently limited by its design to producing waveforms with frequencies far below the clock speed of its microprocessor, and a much faster and accordingly expensive microprocessor is required in order to overcome the limitation. Furthermore, Edward&#39;s device recalculates a change in waveform characteristics only after a session counter has reached a certain parameter value as reflected in a change table. Thus, the device is restricted to producing square waveforms in the interim, and uses up cycles when constantly comparing the counter to the change table, further restricting the frequency of the resultant waveforms.  
         [0007]     It is therefore an object of the present invention to provide a novel portable electrotherapy device for generating specific low frequency pulsed magnetic fields that are used to modify a variety of physiological, neurological and behavioural conditions in vertebrates and invertebrates.  
       SUMMARY OF THE INVENTION  
       [0008]     According to one aspect of the present invention there is provided an electrotherapy device for generating specifically designed low frequency pulsed magnetic fields (Cnp waveforms) comprising:  
         [0009]     memory storing at least one digital Cnp waveform;  
         [0010]     a digital to analog converter converting said at least one digital waveform into an analog Cnp waveform for application to a subject; and  
         [0011]     a processor communicating with said memory, said processor being responsive to operator input and conditioning said memory to output said at least one digital Cnp waveform directly to said digital to analog converter thereby to bypass said processor.  
         [0012]     According to another aspect of the present invention there is provided a portable electrotherapy device for generating specifically designed low frequency pulsed magnetic fields (Cnp waveforms) comprising:  
         [0013]     a controller including a compact housing, said housing having operator controls and an interface thereon and accommodating processing circuitry therein, said processor circuitry including:  
         [0014]     memory storing a plurality of digital Cnp waveforms;  
         [0015]     a digital to analog converter converting a selected one of said digital Cnp waveforms into an analog Cnp waveform for application to a subject; and  
         [0016]     a processor communicating with said memory, said processor being responsive to commands input via said operator controls and conditioning said memory to output a selected one of said digital Cnp waveforms directly to said digital to analog converter thereby to bypass said processor; and  
         [0017]     at least one set of coils coupled to said controller, said coils being worn by a subject and being responsive to said analog Cnp waveform thereby to apply said Cnp waveform to said subject.  
         [0018]     Preferably, the memory is remotely programmable by a computer coupled to the controller via the interface. It is also preferred that the processor stores operating parameters used to control the output of the selected digital Cnp waveform to the digital to analog converter with the processor also being remotely programmable.  
         [0019]     Preferably, the processing circuitry further includes an amplifier connected to the digital to analog converter for boosting the analog Cnp waveform prior to output to the coils. In one form, the set of coils includes a set of head coils. In this case, the digital Cnp waveforms are configured so that resulting analog Cnp waveforms provide shallow to deep brain stimulation when the head coils are worn by the subject. In another form, the set of coils includes a set of wrap coils. In this case, the digital Cnp waveforms are configured so that resulting analog Cnp waveforms provide localized deep tissue exposure when the wrap coils are worn by the subject.  
         [0020]     According to a further aspect of the present invention, there is provided a portable electrotherapy device for generating specifically designed low frequency pulsed magnetic fields (Cnp waveforms) comprising:  
         [0021]     a controller including a compact housing, said housing having user controls and an interface thereon and accommodating processing circuitry therein, said processor circuitry including:  
         [0022]     memory storing a plurality of digital Cnp waveforms;  
         [0023]     a digital to analog converter converting a selected one of said digital Cnp waveforms into an analog Cnp waveform for application to a subject; and  
         [0024]     a processor communicating with said memory, said processor being responsive to commands input via said operator controls and conditioning said memory to output a selected one of said digital Cnp waveforms directly to said digital to analog converter thereby to bypass said processor, and  
         [0025]     a coil coupled to said controller, said coil being worn by a subject and being responsive to said analog Cnp waveform thereby to apply said Cnp waveform to said subject. As will be appreciated, the present invention provides a portable electrotherapy device to deliver low frequency pulsed magnetic fields (Cnp waveforms) to a subject. Previously, the generation of low frequency pulsed magnetic fields required the use of expensive, bulky and heavy equipment connected to a computer, and operated by skilled technicians. The present device offers portable operation without connection to a separate computer and ease of operation, making the device usable by non-technical people.  
         [0026]     The present invention also provides advantages in that since the digital Cnp waveforms stored in the memory are conveyed directly to the digital to analog converter under the control of the processor but not through the processor, analog Cnp waveforms can be generated at a higher speed and with better resolution. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0027]     Embodiments of the present invention will now be described more fully with reference to the accompanying drawings in which:  
         [0028]      FIG. 1  is an illustration of a portable electrotherapy device in accordance with the present invention;  
         [0029]      FIG. 2  is a block diagram of the portable electrotherapy device of  FIG. 1 ;  
         [0030]      FIG. 3  is a schematic diagram of the portable electrotherapy device of  FIG. 1 ; and  
         [0031]      FIG. 4  is a flow chart showing the steps performed by the portable electrotherapy device of  FIG. 1 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0032]     Turning now to  FIG. 1 , an illustration of a portable electrotherapy device for generating specifically designed low frequency pulsed magnetic fields (Cnp waveforms) in accordance with the present invention is shown and is generally identified by reference numeral  10 . As can be seen, portable electrotherapy device  10  includes a microprocessor-based controller  12  and a plurality of coils connectable to the controller. In the present embodiment, the coils include a pair of head coils  14  and a pair of wrap coils  16 , only one of which is shown for ease of illustration. As will be appreciated, the head coils  14  allow Cnp waveforms generated by the portable electrotherapy device to be applied to the brain tissue of a subject. The wrap coils  16  allow Cnp waveforms generated by the portable electrotherapy device to be applied to other area of a subject thereby to stimulate tissue. To facilitate application of Cnp waveforms to a subject&#39;s tissue, the wrap coils  16  are accommodated by holders that are worn by the subject to position properly the wrap coils on the subject&#39;s body. A knee wrap coil holder  18  to position the wrap coils  16  adjacent a subject&#39;s knee is shown for illustrative purposes. It is understood by one of skill in the art that while a pair of coils are shown as head coils or discussed with respect to the wrap coils, one coil may alternatively be used in either aspect.  
         [0033]     Controller  12  includes a compact portable housing  30  having output jacks  32  into which either the head or wrap coils  14  or  16  are plugged to enable the controller  12  to drive the coils. The housing  30  also includes an RS- 232  serial interface  34  to allow the controller  12  to be coupled to a remote computer (not shown). Controls and indicators, as will be described, are provided on the housing  30  enabling an operator to operate the electrotherapy device  10  in the desired manner. An electrical cord  40  extends from the housing  30  allowing the controller  12  to be powered by a conventional 110 VAC power supply.  
         [0034]      FIGS. 2 and 3  illustrate the circuitry  50  within the housing  30 . As can be seen in  FIG. 2 , the circuitry includes a central processing unit (CPU)  52  with random access memory (RAM), input/output (I/O) memory, flash program memory and electrically erasable programmable read only memory (EEPROM). CPU  52  communicates with the serial interface  34 , the controls and the indicators as well as with a pair of serial EEPROMs  54   a  and  54   b . A high resolution digital to analog convertor (DAC)  56  communicates with the EEPROMs  54   a  and  54   b  and with a dual channel high current amplifier  58  that is responsive to phase and gain controls. The amplifier  58  provides analog output to the jacks  32  and hence to the coils. A fused power supply  62  receives input power from the AC power source and provides appropriate DC power to the circuitry  50 .  
         [0035]     Turning now to  FIG. 3 , the circuitry  50  is further illustrated. Power supply  62  is conventional includes a full wave rectifier  62   a  and a series of voltage regulators  62   b ,  62   c  and  62   d  respectively. The voltage regulators provide the DC voltages necessary to power the circuitry  50 .  
         [0036]     The EEPROMs  54   a  and  54   b  are coupled to the serial interface  34  via an RS232 converter  54 . Each EEPROM  54   a ,  54   b  stores a different digital Cnp waveform table. The digital Cnp waveform tables are preloaded into the EEPROMs  54   a  and  54   b  by the remote computer via the serial interface  34 . The digital Cnp waveform tables are characterized by bipolar decimal values that are assembled into analog Cnp waveforms using high resolution digital to analog conversion. The digital Cnp waveform table data is selected so that the portable electrotherapy device  10  generates Cnp waveforms similar to those described in U.S. Pat. No. 6,234,953 to Thomas et al., the contents of which are incorporated herein by reference. Specifically, the digital Cnp waveform table data is selected so that the resulting analog Cnp waveforms provide shallow to deep brain stimulation when the head coils  14  are used and localized deep tissue exposure when the wrap coils  16  are used.  
         [0037]     The amplifier  58  includes a pair of channels, each channel having two amplifying stages. Each amplifying stage includes an input amplifier  72   a ,  72   b  and an output amplifier  72   c ,  72   d . The amplifier  58  supplies enough current to drive the coils to provide a magnetic field density sufficient to deliver a Cnp waveforms having a 100 microTesla peak magnitude field flux density at 8 cm (16 cm between coils). The dual channels of the amplifier  58  permit in-phase or out-of-phase operation of multiple coil configurations.  
         [0038]     The controls on the housing  30  include a power on/off switch  70  on one end panel of the housing  30  adjacent the electrical card  40 . A push button switch  36  is located on the opposite end panel of the housing  30  adjacent the indicators  38   a  and  38   b . The push button switch  36  allows an operator to select the desired Cnp waveform to be output by the electrotherapy device  10  or initiate a digital Cnp waveform table download as will be described. A phase switch  72  and a gain control switch  74  are also provided on the end panel adjacent the push button switch  36 . The phase switch  72  allows the polarity of one of the output channels of the amplifier  58  to be inverted. The gain control switch  74  controls the gain of the amplifier  58  with a 5 to 1 range.  
         [0039]     The EEPROM in the CPU  52  stores a number of digital Cnp waveform operating parameters such as point number, latency period and refractory period. The point number determines the size of the Cnp waveform to be generated by the portable electrotherapy device  10  by specifying the number of points in the digital Cnp waveform table that are used to create the output analog Cnp waveform. The latency period specifies the duration between successive points and the refractory period specifies the time between repeating Cnp waveforms. The digital Cnp waveform operating parameters are downloaded into the EEPROM of the CPU  52  by the remote computer via the serial interface  34  and RS232 converter  54 .  
         [0040]     The operation of the portable electrotherapy device  10  will now be described with reference to FIGS.  1  to  4 . It will be assumed that the digital Cnp waveform tables and operating parameters have been loaded into the EEPROMs and that the coils to be used to simulate the subject are worn by the subject at the appropriate locations. When the controller  12  is powered, the CPU  52  initializes its variables, pointers and registers (step  100 ) and then initializes the serial interface  34  and the DAC  56  (step  102 ). If the operator conditions the controller  12  to generate a Cnp waveform by pressing switch  36  (step  104 ), the CPU  52  selects the EEPROM  54   a ,  54   b  that is to be used to generate the Cnp waveform (steps  106  and  108 ). The CPU  52  also illuminates the indicator  38   a ,  38   b  associated with the selected EEPROM via an amplifier  80   a ,  80   b  to provide the operator with visual feedback concerning the selected digital Cnp waveform table. The CPU  52  then loads the digital Cnp waveform operating parameters stored in its EEPROM (step  110 ). Following this, the CPU  52  conditions the EEPROM  54   a ,  54   b  to transfer the digital Cnp waveform table to the DAC  56  without the digital Cnp waveform table data passing through the CPU  52 . The DAC  56  in turn converts the digital Cnp waveform table into an analog signal (i.e. the Cnp waveform) that is applied to the amplifier  58 . The amplifier  58  in turn boosts the DAC output and supplies the output analog Cnp waveform to the coils via the output jacks  34  (step  112 ). The Cnp waveform generation process continues as specified by the refractory period parameter. If during this process the operator presses the switch  36  again, the CPU  52  conditions the other EEPROM to output its digital Cnp waveform table stored therein and the above steps are re-performed (steps  114  and  116 ). Beneficially, switch  36  is connected via an interrupt line to CPU  52  so that it can immediately respond when switch  36  is pressed, rather than wait until the end of a wave.  
         [0041]     As will be appreciated, during Cnp waveform generation, since the digital Cnp waveform table is transferred directly from the EEPROM  54   a ,  54   b  to the DAC  56  under the timing control of the CPU  52 , but does not pass through the CPU, many CPU instruction cycles are eliminated. This is due to the fact that the need to read serial digital Cnp waveform table data into the CPU and then write the serial digital Cnp waveform table data to the DAC  56  is avoided. The CPU  52  of course has the ability to read and write to the EEPROMs  54   a ,  54   b  and the DAC  56  during periods where no Cnp waveform is being generated. This data transfer method provides for a higher speed, which produces finer time resolution for the output Cnp waveforms.  
         [0042]     At step  104 , if the operator conditions the controller  12  to receive digital Cnp waveform table data from the remote computer by processing the switch  36 , the CPU  52  initializes the EEPROMs  54   a  and  54   b  and the serial interface and awaits input digital Cnp waveform tables from the remote computer (steps  120  and  122 ). When the CPU  52  receives an overwrite command from the remote computer, the CPU  52  erases the appropriate digital Cnp waveform table from the selected EEPROM  54   a ,  4   b  and notifies the remote computer (steps  124  and  126 ). The CPU then awaits receipt of the replacement digital Cnp waveform table (step  128 ). When the digital Cnp waveform table is received from the remote computer, the CPU writes the digital Cnp waveform table to the selected EEPROM (step  130 ).  
         [0043]     If the operator conditions the controller  12  to receive updated digital Cnp waveform operating parameters, the CPU  52  monitors the remote computer for digital Cnp waveform operating parameter input. The digital Cnp waveform operating parameter input is in the form of character strings that are serially loaded into the CPU  52  and stored in a string buffer. Once the digital Cnp waveform operating parameter data is completely received, the CPU  52  stores the new digital Cnp waveform operating parameters into its EEPROM.  
         [0044]     Although the controller  12  is shown as being supplied with power from an AC power source, those of skill in the art will appreciate that the controller may also be fitted with a rechargeable power supply as shown in  FIGS. 2 and 3 , an AC adapter or alternative power supply. For a controller  12  that employs, for instance, batteries, it may be useful to incorporate a battery-power detection circuit, software and an indicator to show a user the power status with the ultimate goal of preventing corruption of the EEPROM parameters due to a low or unusable battery. In addition, the controller  12  need not be remotely programmable. In this case the EEPROMs  54   a  and  54   b  are pre-programmed with the digital Cnp waveform tables of interest and the serial interface  34  is unnecessary.  
         [0045]     It may be envisaged by one of skill in the art to couple an alphanumeric display such as an LCD module to controller  12  in order to display device operational information. To this end, such a display may be used to show to a user any of the active pattern parameters, the name of the pattern and its refractory status (using, for example, a blinking “*”). The display may further be used to replace the pattern indicator LEDs  38   a  and  38   b , reducing unnecessary power consumption, or indicate battery-power status.  
         [0046]     If desired the circuitry  50  may be provided with a balance control to balance the output of the amplifier  58 . Such a balance control could be in the form of a variable potentiometer inserted at the input of the two output amplifiers  72   c ,  72   d  with the center lead grounded so that adjustment of the potentiometer reduces the gain of one output amplifier and increases the gain of the other output amplifier.  
         [0047]     Although preferred embodiments of the present invention have been described, those of skill in the art will appreciate that variations and modifications may be made without departing from the spirit and scope thereof as defined by the appended claims.