Abstract: An implantable infusion device includes a reservoir for housing an infusion medium and a drive mechanism having an inlet chamber, a piston and a piston channel. The inlet chamber is in fluid communication with the reservoir. The piston channel is in fluid communication with the inlet chamber, and has a distal end and a proximal end, the proximal end being closer to the inlet channel than the distal end. The piston is axially moveable within the piston channel to drive infusion medium out of the distal end of the piston channel. The clearance between the piston and the channel is sufficiently small to prevent undissolved gas in the inlet chamber from passing through the clearance. The inlet chamber may be sufficiently large to allow undissolved gas to accumulate without adversely affecting the performance of the infusion device.

Abstract: Techniques are disclosed for reducing the accumulation of gases in an implantable infusion device. In one example, an implantable infusion device (IID) includes a housing, an expandable and contractible reservoir, and a standoff member. The expandable and contractible reservoir is configured to store a therapeutic agent and is arranged within the housing. A first end of the reservoir is configured to collapse toward a second end of the reservoir as the reservoir contracts. The standoff member is interposed between the first end and the second end of the reservoir and is configured to hold at least a portion of the first end offset from the second end when the reservoir is in a contracted state.

Abstract: An implantable infusion device includes a reservoir for housing an infusion medium and a drive mechanism having an inlet chamber, a piston and a piston channel. The inlet chamber is in fluid communication with the reservoir. The piston channel is in fluid communication with the inlet chamber, and has a distal end and a proximal end, the proximal end being closer to the inlet channel than the distal end. The piston is axially moveable within the piston channel to drive infusion medium out of the distal end of the piston channel. The clearance between the piston and the channel is sufficiently small to prevent undissolved gas in the inlet chamber from passing through the clearance. The inlet chamber may be sufficiently large to allow undissolved gas to accumulate without adversely affecting the performance of the infusion device.

Abstract: A method of detecting a fault condition within an implantable medical pump comprises delivering therapeutic fluid using a medical pump comprising an actuation mechanism configured to be energized to provide a pump stroke, detecting a property associated with energizing the actuation mechanism, and determining whether the property associated with energizing the actuation mechanism indicates that a fault condition exists with the medical pump.

Abstract: Detection of end of stroke for an electromagnetic pump may be performed using, for example, a calculated first flux derivative. Further, inductance of a coil that can be energized to produce a pump stroke may be calculated (e.g., the pump may include an actuator moveable in response to the energization of the coil). For example, the inductance may be calculated as a function of sense coil current and source electrical potential when the actuator is not moving for use in determining position of the actuator.

Abstract: An accumulator is employed in an implantable infusion device to provide compliance in the flow path of the device. The accumulator may act to increase the pumping accuracy and repeatability while simultaneously reducing the energy requirements of the device. In one example, the accumulator is arranged at the outlet of a fluid delivery pump of the infusion device. The accumulator includes a cover and a diaphragm biased away from the cover and configured to deflect toward the cover under pressure generated by the therapeutic agent in a flow path of the infusion device. The cover of the accumulator is configured to withstand the pressure generated by the therapeutic agent in the flow path without deforming.

Abstract: An accumulator is employed in an implantable infusion device to provide compliance in the flow path of the device. The accumulator may act to increase the pumping accuracy and repeatability while simultaneously reducing the energy requirements of the device. In one example, the accumulator is arranged at the outlet of a fluid delivery pump of the infusion device. The accumulator includes a cover and a diaphragm biased away from the cover and configured to deflect toward the cover under pressure generated by the therapeutic agent in a flow path of the infusion device. The cover of the accumulator is configured to withstand the pressure generated by the therapeutic agent in the flow path without deforming.

Abstract: Techniques are disclosed for reducing the accumulation of gases in an implantable infusion device. In one example, an implantable infusion device (IID) includes a housing, an expandable and contractible reservoir, and a standoff member. The expandable and contractible reservoir is configured to store a therapeutic agent and is arranged within the housing. A first end of the reservoir is configured to collapse toward a second end of the reservoir as the reservoir contracts. The standoff member is interposed between the first end and the second end of the reservoir and is configured to hold at least a portion of the first end offset from the second end when the reservoir is in a contracted state.

Abstract: A method of detecting a fault condition within an implantable medical pump comprises delivering therapeutic fluid using a medical pump comprising an actuation mechanism configured to be energized to provide a pump stroke, detecting a property associated with energizing the actuation mechanism, and determining whether the property associated with energizing the actuation mechanism indicates that a fault condition exists with the medical pump.

Abstract: Detection of end of stroke for an electromagnetic pump is performed using, for example, a calculated first flux derivative.

Abstract: Detection of end of stroke for an electromagnetic pump is performed using, for example, a calculated first flux derivative.

Abstract: An implantable drug delivery device includes a pump motor that is driven by electrical energy from a storage capacitor. At the end of each pump delivery cycle, electrical energy stored in the pump motor is recovered and returned to the storage capacitor, so that it can be used in subsequent delivery cycles.

Abstract: The present invention relates to a method and related apparatus for rotating a piston of a drug pump during the pumping stroke to reduce drug pump wear. The actuator may move a piston that pumps fluid through a pumping channel. In the present invention, the armature includes one or more openings or shapes that cause the actuator, including the armature and the piston, to rotate about a longitudinal axis of the piston during the pumping stroke. Rotation of the actuator member may help to reduce wear to the actuator member and the pump itself caused by repetitive pumping motions.

Abstract: An implantable infusion device includes a reservoir for housing an infusion medium and a drive mechanism having an inlet chamber, a piston and a piston channel. The inlet chamber is in fluid communication with the reservoir. The piston channel is in fluid communication with the inlet chamber, and has a distal end and a proximal end, the proximal end being closer to the inlet channel than the distal end. The piston is axially moveable within the piston channel to drive infusion medium out of the distal end of the piston channel. The clearance between the piston and the channel is sufficiently small to prevent undissolved gas in the inlet chamber from passing through the clearance. The inlet chamber may be sufficiently large to allow undissolved gas to accumulate without adversely affecting the performance of the infusion device.

Abstract: A drive mechanism for delivery of infusion medium in an implantable medical device includes an inlet for receiving the infusion medium and a piston channel for communication of infusion medium received by the inlet. The piston channel has a distal end and a proximal end. The proximal end is closer to the inlet than the distal end. The drive mechanism further includes a coil surrounding the piston channel and a piston located within the piston channel and moveable axially within the piston channel to drive infusion medium out of the distal end of the piston channel. The mechanism also includes an armature operably coupled to the piston and disposed adjacent the coil. The armature has first and second opposing major surfaces and a plurality of vents extending through the armature from the first major surface to the second major surface. The plurality of vents cumulatively occupy between about 20% and about 40% of the total surface area of the first major surface.

Abstract: The present invention is an actuator for a piston pump that includes a separately formed piston and armature. The piston and the armature are later assembled together or are inserted into the piston pump in such a manner as to cooperate during pumping. Assembling the piston and the armature as separate components may provide for improved form of the piston component when manufactured separately from the armature, due to, for example, increased simplification of the manufacturing process. In addition, effects of manufacturing the piston and the armature together, such as stress on the piston, may be reduced.

Abstract: Detection of end of stroke for an electromagnetic pump is performed using, for example, a calculated first flux derivative.

Abstract: The present invention relates to a method and related apparatus for rotating a piston of a drug pump during the pumping stroke to reduce drug pump wear. The actuator may move a piston that pumps fluid through a pumping channel. In the present invention, the armature includes one or more openings or shapes that cause the actuator, including the armature and the piston, to rotate about a longitudinal axis of the piston during the pumping stroke. Rotation of the actuator member may help to reduce wear to the actuator member and the pump itself caused by repetitive pumping motions.

Abstract: An implantable drug delivery device includes a pump motor that is asserted by drive currents from a storage capacitor. A programmable rate charge control delivers charging current from a battery to the storage capacitor based upon a programmable charge rate value, a minimum battery voltage value, sensed charging current, and sensed battery voltage. When sensed battery voltage droops to below a threshold value, the charge control reduces the charging rate value until other electrical loads within the drug device have been serviced and battery voltage is restored. The charge control also monitors capacitor voltage and provides a charge complete signal to a motor control, which then connects the pump motor to the storage capacitor to produce a pump stroke. Efficiency of charging is enhanced by controlling the charging at a programmable substantially constant rate.

Abstract: An implantable drug delivery device includes a pump motor that is driven by electrical energy from a storage capacitor. At the end of each pump delivery cycle, electrical energy stored in the pump motor is recovered and returned to the storage capacitor, so that it can be used in subsequent delivery cycles.