Implantable infusion device with optimized peristaltic pump motor drive

• US 20030199855A1
• Filed: 04/22/2002
• Published: 10/23/2003
• Est. Priority Date: 04/22/2002
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Rogers, Charles R., Seifert, George P.
• Granted Patent: US 7,122,026 B2
• Time in Patent Office: Days
• US Class Current: 604/891.1
• CPC Class Codes: A61M 2205/8212 with means or measures taken for minimising energy consumption
• CPC Class Codes: A61M 5/14276 specially adapted for implantation
• CPC Class Codes: A61M 5/172 electrical or electronic A61M5/16804, A61M5/16831 take precedence
• CPC Class Codes: H02P 8/16 Reducing energy dissipated or supplied

Abstract

A medical device known as an implantable therapeutic substance delivery device is configured for implanting in humans to deliver a therapeutic substance such as pharmaceutical compositions, genetic materials, and biologics to treat a variety of medical conditions such as pain, spasticity, cancer, and many other conditions. The infusion device incorporates a stepper motor that controls the infusion flow rate during the service life of the device. The stepper motor is controlled by continuously varying electrical pulse parameters based on the continuously decreasing power source voltage during the service life of the substance delivery device. In particular the stepper motor electrical pulse parameters, especially duty cycle, are selected to efficiently compensate for decreasing battery voltage thereby optimizing the motor performance while maximizing the power source service life. The infusion device has a housing, a power source, a therapeutic substance reservoir, a therapeutic substance pump, and electronics. Many embodiments of the therapeutic substance delivery device with optimized pump motor drive and its methods of operation are possible.

Claims

1. An implantable infusion device with energy efficient motor drive, comprising:

a housing;

a power source carried in the housing;

a therapeutic substance reservoir carried in the housing, the therapeutic substance reservoir configured for containing a therapeutic substance and being refilled with the therapeutic substance while implanted;

a therapeutic substance pump carried in the housing, the therapeutic substance pump fluidly coupled to the therapeutic substance reservoir, and electrically coupled to the power source;

a motor coupled to the power source and coupled to the therapeutic substance pump;

electronics carried in the housing, the electronics coupled to the motor and the power source, the electronics including,

a processor,

memory coupled to the processor,

an infusion program residing in memory, the infusion program capable of being modified once the therapeutic substance infusion device is implanted;

transceiver circuitry coupled to the processor for externally receiving and transmitting therapeutic substance infusion device information;

a power source measurement circuit to measure power source voltage; and

,

a motor drive circuit configured to generate a varying duty cycle of drive pulses in a substantially fixed drive interval, the varying duty cycle of drive pulses varying according to the power source voltage measured by the power source measurement circuit to optimize and reduce motor energy consumption.

2. The implantable infusion device as in claim 1 wherein the motor drive circuit comprises,

a drive interval timing circuit that specifies a substantially fixed drive interval for drive energy to be delivered to the motor to operate a therapeutic substance pump according to a therapy program;

and,

a drive pulse circuit coupled to the power source measurement circuit that generates a predetermined number of drive pulses within the drive interval according to the power supply voltage to reduce motor energy consumption.

3. The implantable infusion device as in claim 1 wherein the predetermined number of drive pulses are in the range from about 10 to about 25 drive pulses within the substantially fixed drive interval.

4. The implantable infusion device as in claim 1 wherein the drive interval has a duty cycle in the range from about 75% to about 100% of the step interval.

5. The implantable infusion device as in claim 1 wherein the predetermined number of drive pulses is selected to operate the stepper motor while substantially maintaining motor stability and substantially avoid motor stall.

6. The implantable infusion device as in claim 1 wherein the motor drive circuit uses logic contained in registers to configure the drive pulses.

7. The implantable infusion device as in claim 6 wherein registers include a pulse interval register, a drive pulse width register, a drive pulse duty cycle register, and a drive pulse expiration register.

8. The implantable infusion device as in claim 1 further comprising a power source forecast circuit or program that identifies that the power source voltage will change abruptly and that the drive duty cycle must be adjusted.

9. An energy efficient motor drive for an implantable infusion device, comprising:

a power source measurement circuit to measure power source voltage; and

,

a drive interval timing circuit that specifies a substantially fixed drive interval for drive energy to be delivered to the motor to operate a therapeutic substance pump according to a therapy program; and

,

a drive pulse circuit coupled to the power source measurement circuit that generates a predetermined number of drive pulses within the drive interval according to the power supply voltage to reduce energy consumption of the motor.

10. A method for reducing energy consumption in a implantable infusion device, comprising:

receiving an instruction to infuse a therapeutic substance;

measuring power source voltage;

calculating a duty cycle of the drive pulses to delivery within a substantially fixed drive interval to operate a stepper motor;

delivering the varying duty cycle drive pulses within a substantially fixed drive interval to operate the stepper motor; and

,

infusing therapeutic substance when the stepper motor operates a peristaltic pump to meter therapeutic substance from a therapeutic substance reservoir into an infusion outlet.