Functional electrical stimulus unit

• US 9,486,627 B1
• Filed: 10/30/2009
• Issued: 11/08/2016
• Est. Priority Date: 11/04/2008
• Status: Expired due to Fees

• Current Assignee: Carter B. White
• Original Assignee: Carter B. White
• Inventors: White, Carter B.
• Primary Examiner(s): Malamud, Deborah
• Application Number:
  US12/589,953
• Time in Patent Office: 2,566 Days
• Field of Search: 607 1- 2, 607 48- 49, 607/115, 607/144
• US Class Current: 1/1
• CPC Class Codes: A61B 2562/0257 Proximity sensors
• CPC Class Codes: A61B 5/112 Gait analysis
• CPC Class Codes: A61B 5/1126 using a particular sensing technique
• CPC Class Codes: A61B 5/6828 Leg
• CPC Class Codes: A61B 5/7225 Details of analog processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation A61B5/30, A61B5/316 take precedence; transformers for specific applications H01F38/00; amplifiers H03F
• CPC Class Codes: A61N 1/0452 Specially adapted for transcutaneous muscle stimulation [TMS]
• CPC Class Codes: A61N 1/18 Applying electric currents by contact electrodes
• CPC Class Codes: A61N 1/36003 of motor muscles, e.g. for walking assistance
• CPC Class Codes: A61N 1/36031 using physiological parameters for adjustment
• CPC Class Codes: A61N 1/36034 specified by the stimulation parameters

Abstract

A functional electrical stimulation method and device that starts electrical stimulation of a first leg of a person when a distance between a reference point on the person'"'"'s first leg and the surface on which the person walks exceeds a first predetermined value and stops electrical stimulation of the first leg of the person when the distance between the reference point and the surface falls below a second predetermined value, wherein the first and second predetermined values are calculated from an initial measurement of the distance between the reference point and the surface when the person is standing still and the first leg is perpendicular to the surface. The first predetermined value is greater than the second predetermined value. The method and device produce a more natural gait in persons with drop foot, and minimize the time electrical stimulation is applied to muscles so as to minimize muscle fatigue.

Claims

1. A device comprising:

1) a first means for starting electrical stimulation of a first leg of a person when a distance between a reference point on the person'"'"'s first leg and the surface on which the person walks exceeds a first predetermined value; and

2) a second means for stopping electrical stimulation of the first leg of the person when the distance between the reference point on the person'"'"'s first leg and the surface falls below a second predetermined value.

2. The device of claim 1 wherein the first predetermined value exceeds the second predetermined value.

3. The device of claim 1 wherein the first and second predetermined values are calculated on the basis of an initial recorded distance between the reference point on the person'"'"'s first leg and the surface.

4. A functional electrical stimulator comprising:

1) a control unit removably attached to a first leg of a person standing on a surface, the control unit comprising a source of electrical power;

2) a first means of measuring in real time the distance between the control unit and the surface;

3) a second means for recording a reference distance between the control unit and the surface during an initialization procedure that occurs when the person is standing generally still with the first leg generally perpendicular to the surface;

4) a third means for continually comparing the real time distance measured to the reference distance, after the reference distance has been recorded; and

5) a fourth means for commanding an electrical signal to be generated and transmitted to a particular part of the first leg whenever the real time distance exceeds the reference distance by a first predetermined percentage, and continuing to generate and transmit the electrical signal until such time as the real time distance falls below a second predetermined percentage of the reference distance;

wherein the first predetermined percentage is greater than the second predetermined percentage.

5. The functional electrical stimulator of claim 4 further including:

1) a fifth means for ramping up the electrical signal from zero to full signal over a first predetermined period of time when the fourth means commands the electrical signal to be generated;

2) a sixth means for ramping down the electrical signal from full signal to zero over a second predetermined period of time when the fourth means ceases commanding the electrical signal;

wherein the second predetermined period of time is greater than the first period of time.

6. The functional electrical stimulator of claim 4 further including:

a remote control means for controlling the control unit.

7. The functional electrical stimulator of claim 4 further including:

a means for programming the control unit including means to program the first and second predetermined percentages.

8. The functional electrical stimulator of claim 4 wherein the control unit has a signal means for communicating multiple events to the person by generating and sending to the person'"'"'s first leg a different pulse train for each one of the multiple events.

9. A method comprising the steps of:

1) measuring, in real time, the distance between a control unit removably attached to a first leg of a person and a surface on which the person stands;

2) recording a reference distance between the control unit and the surface at a time when the person is standing generally still and when the first leg is generally perpendicular to the surface;

3) thereafter, continually comparing the real time distance measured to the reference distance; and

4) generating an electrical signal and transmitting it to a part of the first leg of the person whenever the real time measured distance exceeds the reference distance by a first predetermined percentage, and thereafter continuing to generate and transmit the electrical signal until such time that the real time measured distance is less than a second predetermined percentage of the reference distance.

10. The method of claim 9 wherein the first predetermined percentage is greater than the second predetermined percentage.

11. The method of claim 9 wherein, during the electrical signal generation step, the electrical signal is ramped-up over a first predetermined period of time from zero to full signal.

12. The method of claim 9 wherein, when the real time measured distance is less than the second predetermined percentage of the reference distance, the electrical signal generated and transmitted to the first leg is ramped-down over a second predetermined period of time from full signal to zero.

13. The method of claim 9 wherein, during the electrical signal generation step, the electrical signal is ramped-up over a first predetermined period of time from zero to full signal;

and wherein, when the real time measured distance is less than the second predetermined percentage of the reference distance, the electrical signal generated and transmitted to the first leg is ramped-down over a second predetermined period of time from full signal to zero;

with the first predetermined period of time being shorter than the second predetermined period of time.

14. An electrical stimulation apparatus comprising:

1) a control unit removably attached to a person'"'"'s first leg;

2) a means for initially measuring a reference distance between the control unit and the surface on which the person stands and walks, when the person is relatively stationary with the person'"'"'s first leg relatively perpendicular to the surface;

3) a means for determining a first predetermined multiple of the reference distance, and for determining a second predetermined multiple of the reference distance;

4) a means for subsequently continuously measuring in real time the distance between the control unit and the surface, and for continuously comparing the real time measured distance with the reference distance; and

5) a means for generating and transmitting electrical stimulation to the first leg, the electrical stimulation ramping up to full value beginning when the real time distance exceeds the first predetermined multiple of the reference distance and ramping down from full value to zero beginning when the real time distance falls below the second predetermined multiple of the reference distance.

15. A means for providing electrical stimulation to a person comprising:

1) a source of electrical power;

2) a liner voltage regulator;

3) a programmable microcontroller powered by the source of electrical power;

the microcontroller having an addressable analog-to-digital converter, a universal synchronous asynchronous receiver transmitter (USART), multiple input-output ports, and a nonvolatile memory;

4) at least one output circuit for delivering electrical stimulation to a person, each output circuit comprising;

(a) a first switchable driver means for driving the primary winding of a first step-up transformer, and

(b) a first means for applying power to a part of a person'"'"'s body, the first means for applying power being connected across the secondary winding of the first step-up transformer;

5) a means for determining a first physical distance and producing an electrical signal that is proportional to the magnitude of the first physical distance; and

6) a means to receive programming information and transmit it to the programmable microcontroller;

wherein the microcontroller monitors the electrical signal that is proportional to the first physical distance, and commands each output circuit to deliver electrical stimulation to the person whenever the electrical signal equals a first predetermined level and, thereafter, continues commanding each output circuit to deliver electrical stimulation until the electrical signal reaches a second predetermined level, at which time the microcontroller ceases commanding each output circuit to deliver electrical stimulation until such time as the electrical signal equals the first predetermined level.

16. A means for providing functional electrical stimulation to a person comprising:

1) a source of electrical power;

2) a first diode having its anode connected to the positive terminal of the means for providing power;

3) a power switch having a first terminal connected to the cathode of the first diode and a second terminal connected to a first circuit bus line;

4) a liner voltage regulator having its input connected to the first circuit bus line, a first output connected to a second circuit bus line, and a second output connected to a third circuit bus line;

5) a capacitor having its positive terminal connected to the third circuit bus line and its negative terminal connected to the second circuit bus line;

6) a programmable microcontroller being powered by a connection to the third circuit bus line;

the microcontroller having an addressable analog-to-digital converter, a universal synchronous asynchronous receiver transmitter, multiple input-output ports, and nonvolatile flash memory;

7) a distance means for determining a first physical distance wherein the distance means comprises a circuit that produces a first electrical signal that represents the first physical distance determined by the distance means;

8) means for transmitting the first electrical signal of the distance means to an input port of the microcontroller; and

9) at least one output circuit, each output circuit comprising;

(a) a first NPN transistor having its collector connected to the first circuit bus line,

(b) a first potentiometer having a first terminal connected to the emitter of the first NPN transistor,

(c) a first resistor having a first terminal connected to a second terminal of the first potentiometer and having a second terminal connected to the second circuit bus line,

(d) a first Darlington transistor having its emitter connected to the second circuit bus line, and its base connected to the adjustable terminal of the first potentiometer through a second resistor,

(e) a first step-up transformer having one primary winding terminal connected to the collector of the first Darlington transistor and a second primary winding terminal connected to the first circuit bus line, and having its secondary winding connected across a first output power jack to which electrode pads may be connected,

(f) a second diode connected in parallel to the primary winding of the first step-up transformer with the second diode'"'"'s anode connected to the collector of the first Darlington transistor and the second diode'"'"'s cathode connected to the first circuit bus line, and

(g) a third resistor with a first terminal connected to the base of the first NPN transistor and a second terminal connected to an output port of the microcontroller.

17. The means for providing functional electrical stimulation of claim 16 wherein the distance means for determining a first physical distance is a distance measuring sensor which detects reflected infrared radiation.

18. The means for providing functional electrical stimulation of claim 16 further comprising a means for receiving a control signal from a remote control, a means for converting the control signal to an electrical signal, and a means for transmitting the electrical signal to an input of the microcontroller.

19. A means for providing functional electrical stimulation to a person comprising:

1) a source of electrical power;

2) a first diode having its anode connected to the positive terminal of the means for providing power;

3) a power switch having a first terminal connected to the cathode of the first diode and a second terminal connected to a first circuit bus line;

4) a liner voltage regulator having its input connected to the first circuit bus line, a first output connected to a second circuit bus line, and a second output connected to a third circuit bus line;

5) a capacitor having its positive terminal connected to the third circuit bus line and its negative terminal connected to the second circuit bus line;

6) a programmable microcontroller being powered by a connection to the third circuit bus line;

the microcontroller having an addressable analog-to-digital converter, a universal synchronous asynchronous receiver transmitter, multiple input-output ports, and nonvolatile flash memory;

7) a distance means for determining a first physical distance wherein the distance means comprises a circuit that produces an first electrical signal that represents the first physical distance determined by the distance means;

8) means for transmitting the first electrical signal of the distance means to an input port of the microcontroller;

9) a first output circuit comprising;

(a) a first NPN transistor having its collector connected to the first circuit bus line,

(b) a first potentiometer having a first terminal connected to the emitter of the first NPN transistor,

(c) a first resistor having a first terminal connected to a second terminal of the first potentiometer and having a second terminal connected to the second circuit bus line,

(d) a first Darlington transistor having its emitter connected to the second circuit bus line, and its base connected to the adjustable terminal of the first potentiometer through a second resistor,

(e) a first step-up transformer having one primary winding terminal connected to the collector of the first Darlington transistor and a second primary winding terminal connected to the first circuit bus line, and having its secondary winding connected across a first output power jack to which electrode pads may be connected,

(f) a second diode connected in parallel to the primary winding of the first step-up transformer with the second diode'"'"'s anode connected to the collector of the first Darlington transistor and the second diode'"'"'s cathode connected to the first circuit bus line, and

(g) a third resistor with a first terminal connected to the base of the first NPN transistor and a second terminal connected to an output port of the microcontroller; and

10) a second output circuit comprising;

(a) a second NPN transistor having its collector connected to the first circuit bus line,

(b) a second potentiometer having a first terminal connected to the emitter of the second NPN transistor,

(c) a fourth resistor having a first terminal connected to a second terminal of the second potentiometer and having a second terminal connected to the second circuit bus line,

(d) a second Darlington transistor having its emitter connected to the second circuit bus line, and its base connected to the adjustable terminal of the second potentiometer through a fifth resistor,

(e) a second step-up transformer having one primary winding terminal connected to the collector of the second Darlington transistor and a second primary winding terminal connected to the first circuit bus line, and having its secondary winding connected across a second output power jack to which electrode pads may be connected,

(f) a third diode connected in parallel to the primary winding of the second step-up transformer with the third diode'"'"'s anode connected to the collector of the second Darlington transistor and the third diode'"'"'s cathode connected to the first circuit bus line, and

(g) a sixth resistor with a first terminal connected to the base of the second NPN transistor and a second terminal connected to an output port of the microcontroller.

20. The means for providing functional electrical stimulation of claim 19 wherein the distance means for determining a first physical distance is a distance measuring sensor which detects reflected infrared radiation.

21. The means for providing functional electrical stimulation of claim 19 further comprising a means for receiving an infrared signal from a remote control, a means for converting the infrared signal to an electrical signal, and a means for transmitting the electrical signal to an input of the microcontroller.