Pumps – Condition responsive control of pump drive motor – By control of electric or magnetic drive motor
Reexamination Certificate
2001-12-27
2003-07-22
Freay, Charles G. (Department: 3746)
Pumps
Condition responsive control of pump drive motor
By control of electric or magnetic drive motor
C417S053000, C604S890100
Reexamination Certificate
active
06595756
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to electronic control systems, configurations and processes for electromagnetic pumps and, in particular embodiments, to such systems, configurations and processes for efficient utilization of power and reduction of power consumption requirements in electromagnetic pumps. Further embodiments of the invention relate to electromagnetic pumps which employ such systems, configurations and processes and yet further embodiments relate to infusion devices and, more preferably, implantable infusion devices which employ electromagnetic pumps having such electronic control systems, configurations and processes.
RELATED ART
Infusion devices are typically used to deliver an infusion medium, such as a medication, to a patient. Implantable infusion devices are designed to be implanted in a patient's body to administer an infusion media to the patient at a regulated dosage, over a period of time. External infusion devices may be designed to be portable, for example, to be worn outside of a patient's body and connected to the patient by a catheter. Other forms of infusion devices are non-portable devices, typically for use in a controlled environment, such as a hospital.
Infusion devices typically include an electromagnetic pump mechanism that is operated to, selectively drive infusion medium to the patient. Various forms of electromagnetic pumps have been developed for use in infusion devices operating in external or implant environments. Examples of such pumps include those described in U.S. Pat. No. 4,594,058 to Fischell; U.S. Pat. No. 4,684,368 to Kenyon; U.S. Pat. No. 4,569,641 to Falk et al.; U.S. Pat. No. 4,568,250 to Falk, et al.; U.S. Pat. No. 4,636,150 to Falk, et al.; and U.S. Pat. No. 4,714,234 to Falk et al.
Typical electromagnetic pump configurations, such as those described in the above-referenced patents, employ a conductive coil coupled to a battery, through control electronics. The coil is selectively energized by the power source and control electronics to create an electromagnetic field which operates on a moveable armature. When the coil is energized, the electromagnetic field causes the armature to move against the force of a spring, toward a stroke position. When the coil is then de-energized, the mechanical spring force returns the armature to the position it had prior to energizing the coil. By moving the armature between its energized stroke position and its return position, a pumping action is accomplished.
In some contexts of use, infusion devices may be operable for an extended period with a limited power supply. For example, battery powered infusion devices may be implanted in or otherwise connected to patients, to deliver medication at controlled intervals over a prolonged period of time. As the battery power supplies have limited capacities, such devices may require multiple replacements of batteries over their operational life. In the case of an implanted infusion device, a replacement of a battery may require the surgical removal of the infusion device. Even with external devices, the replacement of a battery may require specialized tools, parts or skills which necessitate the services of a specialist or trained technician. Thus, a patient requiring a battery replacement may experience inconveniences and costs associated with seeing specialists, while implant patients may further experience the risks, trauma and costs of surgery. Accordingly, there is a demand in the industry for infusion devices which make efficient use of power supplies and, thus, require fewer power supply replacements. This demand is particularly important for implantable devices.
Prior infusion device pumps, such as the P650005 made by Wilson Greatbatch, Ltd., employ capacitor-discharge power control circuits. Such power control circuits include a capacitor that is charged by a battery and discharged to a coil, to power the pump operation. In one representative example, such power control circuits employ a 47 micro-Farad capacitor which is charged at about 16 volts. Each complete discharge of the capacitor delivers an electric power pulse to the coil sufficient to energize the coil and cause the pump to make one complete stroke. The capacitor is fully charged by the battery between pump stokes.
Because a given capacitor charged to a given voltage level produces a fixed amount of power per complete discharge, the pump receives a fixed amount of power independent of the pump's power needs. However, the power requirements of the pump can vary due to many different factors, such as the formation of partial blockages in the flow path, changes in atmospheric pressure (which may occur, for example, if a patient travels to a high altitude location or swims or dives under water), or changes in the volume of stored infusion medium.
In order to operate the pump under all expected power load conditions, the capacitor size in such prior devices is selected such that the power output per complete discharge is sufficient to operate the pump in the greatest expected power load condition. As a result, sufficient power to operate the pump in the greatest expected load condition is provided to the pump, even when the pump is not operating under the greatest expected load. Such a power discharge at every pump operation, independent of the pump's power needs, results in a significant waste of electric power.
Accordingly, there is a demand in the industry for electronic power control systems and processes for electromagnetic pumps which provide sufficient power to operate the pump under varying load conditions, but which minimize or decrease power consumption requirements as compared to prior power control systems. There is a further need in the industry for electromagnetic pump configurations which minimize or reduce power consumption requirements as compared to prior pump configurations.
SUMMARY OF THE DISCLOSURE
Embodiments of the present invention relate to electric power control systems and processes, infusion devices and pumps for infusion devices which address the above-mentioned industry demands.
Embodiments of the invention relate to electronic control systems and process, infusion devices and pump configurations for highly efficient use of electrical power. Preferred embodiments relate to such power efficient systems and processes for prolonged operational life with a depletable power source, such as, for example, a battery. Several aspects and features of electronic power control systems and processes and pump configurations described herein allow reduced or minimized power consumption requirement for a given infusion output volume. Various embodiments of the invention include one or more of such aspects and features for improved power consumption efficiency.
Preferred embodiments of the invention relate to electronic control systems and process, infusion devices and pump mechanisms configured for implantation in a patient's body. Further preferred embodiments employ power consumption efficiency aspects and features referenced above to provide improved operational life within an implant environment.
Yet further preferred embodiments relate to such devices and pump mechanisms configured to deliver relatively precisely controlled volumes of infusion medium, within a relatively wide range of volumes, including relatively small volumes.
Yet further preferred embodiments relate to such devices and pump mechanisms configured to deliver sufficiently precise volumes of relatively high concentration infusion medium.
An infusion device according to an embodiment of the invention includes a generally disc-shaped housing made from a biocompatible material. The housing contains a reservoir for holding a volume of infusion medium, such as, but not limited to, a medication to be administered to the patient. The housing has an outlet through which the infusion medium may be expelled. The reservoir is coupled in fluid flow communication with the outlet.
The infusion device also includes or operates with a pump mechanism coupled
Bosley Robert W.
Gray John
Freay Charles G.
Liu Han L.
Medtronic MiniMed, Inc.
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