System and method of generating electrical stimulation waveforms as a therapeutic modality

• US 20070299895A1
• Filed: 06/11/2007
• Published: 12/27/2007
• Est. Priority Date: 06/09/2006
• Status: Abandoned Application

• Current Assignee: Axiom Worldwide, Inc.
• Original Assignee: Axiom Worldwide, Inc.
• Inventors: Johnson, Scot, DeWeerd, Andrew
• Application Number:
  US11/811,485
• Publication Number:
  US 20070299895A1
• Time in Patent Office: Days
• US Class Current: 708/270
• CPC Class Codes: A61N 1/323 Interference currents, i.e. treatment by several currents summed in the body
• CPC Class Codes: A61N 1/36034 specified by the stimulation parameters
• CPC Class Codes: G06F 1/0321 Waveform generators, i.e. devices for generating periodical functions of time, e.g. direct digital synthesizers G06F1/0314, G06F1/035 take precedence
• CPC Class Codes: H03G 3/3021 by varying the duty cycle

Abstract

Embodiments of the present invention provide an apparatus and method of generating electrical stimulation waveforms using Direct Digital Synthesis (DDS). The waveform generation substantially reduces intensive processor calculations and commands required for the generation of waveforms via Pulse Width Modulation (PWM). DDS technology is integrated into single-integrated circuit components, capable of generating waveforms based on singular digital word commands. The use of DDS integrated circuits allows for rapid changes in frequencies, automatically sweeps frequencies between user defined limits, and are capable of a wide range of frequencies. Further, utilization of DDS in waveform generation allows for software updatable functionality. Additionally, because DDS technology outputs a smooth sine wave, the need for extensive filtering is drastically reduced. Further, DDS technology can be utilized in an amplitude modulation stage beyond the DDS waveform generator, further reducing the burden on processor systems.

Claims

1. A system comprising:

a processor;

a DDS circuit;

a filtering circuit;

a gain loop including a digital potentiometer,

a step-up transformer, and

an electrode pair for creating and delivering electrical stimulation to a patient,

said processor issuing digital words to said DDS circuit, the digital words instructing said DDS circuit to generate a sine waveform at an instructed frequency, said DDS circuit delivers the sine waveform output to said filtering circuit, the filtered waveform being delivered to said gain control loop that receives commands from said processor that change digital potentiometer values and adjust waveform amplitude, the amplitude adjusted waveform being fed through a step-up transformer whose output is fed through wires to said electrode pair that is placed on a patient'"'"'s body.

2. The invention of claim 1 wherein said DDS circuit includes a sweep generator such than a single command to said DDS circuit from said processor generates and sweeps the frequency of the sine waveform automatically.

3. The invention of claim 1 wherein said DDS circuit includes an accumulator, a Sine ROM, and a Digital to Analog converter, said DDS circuit interpreting the digital words as a frequency for an output sine wave, said accumulator counting out a signal based on information from the digital word, the signal being delivered to said Sine ROM for defining at least one period of the output sine wave, the signal being communicated from said Sine ROM to the said Digital to Analog converter, said Digital to Analog converter converts the signal to the output sine wave.

4. The system of claim 1 wherein the digital words instruct said DDS to generate the sine waveform at a frequency above 2000 Hz.

5. The system of claim 4 wherein said processor communicates the digital words in series to said DDS circuit.

6. The system of claim 4 wherein the processor communicates the digital words in parallel to said DDS circuit.

7. A system comprising:

a processor;

a first DDS circuit;

a filtering circuit;

a gain loop including a second DDS circuit;

a step-up transformer; and

an electrode pair for creating and delivering electrical stimulation to a patient,

said processor issuing digital words to said first DDS circuit, the digital words instructing said first DDS circuit to generate a sine waveform at an instructed frequency, said first DDS circuit delivers the sine waveform output to said filtering circuit, the filtered waveform being delivered to said gain control loop that receives commands from said processor instructing said second DDS circuit to automatically adjust waveform amplitude, the amplitude adjusted waveform being fed through said step-up transformer whose output is fed through wires to said electrode pair positioned on a patient'"'"'s body.

8. The invention of claim 7 wherein said DDS circuit includes a sweep generator such than a single command to said DDS circuit from said processor generates and sweeps the frequency of the sine waveform automatically.

9. The invention of claim 7 wherein said first DDS circuit includes an accumulator, a Sine ROM, and a Digital to Analog converter, said DDS circuit interpreting the digital words as a frequency for an output sine wave, said accumulator counting out a signal based on information from the digital word, the signal being delivered to said Sine ROM for defining at least one period of the output sine wave, the signal being communicated from said Sine ROM to the said Digital to Analog converter, said Digital to Analog converter converts the signal to the output sine wave.

10. The system of claim 7 wherein the digital words instruct said DDS to generate the sine waveform at a frequency above 2000 Hz.

11. The system of claim 8 wherein said processor communicates the digital words in series to said DDS circuit.

12. The system of claim 8 wherein the processor communicates the digital words in parallel to said DDS circuit.

13. A method for generating electrical stimulation waveforms comprising the steps of:

a. issuing at least one digital word from a processor to a first DDS circuit, the at least one digital word instructing said first DDS circuit to generate a sine waveform at an instructed frequency;

b. filtering the sine waveform through a filtering circuit, the filtering circuit outputting a filtered sine waveform;

c. adjusting the amplitude of the filtered sine waveform.

d. feeding the amplitude adjusted filtered sine waveform through a step-up transformer wherein the voltage of the amplitude adjusted filtered waveform is stepped up to levels sufficient for electrical stimulation therapy; and

e. passing the amplitude adjusted filtered sine waveform outputted from the step-up transformer to an electrode pair positioned on a patient'"'"'s body.

14. The method of claim 13 wherein the step of adjusting the amplitude of the filtered sine waveform includes the delivering commands from the processor to a gain control loop instructing a second DDS circuit to automatically adjust waveform amplitude.

15. The method of claim 13 wherein the step of adjusting the amplitude of the filtered sine waveform includes the delivering commands from the processor to a gain control loop that change digital potentiometer values and adjust waveform amplitude.