Chemistry: electrical current producing apparatus – product – and – Having diverse cells or diverse removable cells in a support...
Reexamination Certificate
1998-07-24
2001-05-29
Maples, John S. (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Having diverse cells or diverse removable cells in a support...
C429S099000, C429S176000, C607S036000
Reexamination Certificate
active
06238813
ABSTRACT:
TECHNICAL FIELD
The invention relates generally to electrochemical batteries and, in particular, to electrochemical batteries for use in implantable medical devices.
BACKGROUND
The battery of an implanted medical device should have a reliable, long life. Engineering progress in battery design has lead to substantial reductions in battery volume while maintaining, or improving upon, the device longevity. This reduction in battery volume has resulted in smaller and more comfortable devices for the patient.
Implantable cardiac defibrillators (ICDs) generally have monitoring and control circuitry to sense and analyze cardiac events, and electrical output circuitry to provide both pacing level and defibrillation level electrical energy to the cardiac tissue in response to the control circuitry. These ICD circuitry components, however, have different power requirements. While the monitoring and the pacing control and output circuitry require a continuous low-current supply over the life of the ICD, the defibrillation output circuitry require a high-current supply for very short time durations to enable the defibrillation electrical output circuitry to deliver a defibrillation level shock to the patient in a timely manner. Therefore, one of the challenges in designing ICDs is the integration of these circuitry components with vastly different power requirements into a ICD using a single current battery.
Typically, two lithium silver vanadium pentoxide batteries coupled in series have been used to achieve the high-current, high power density, requirements for the ICDs defibrillation output circuity. This high power capability battery design is suited for the high-voltage defibrillation output circuity which draws peak current drains on the order of amperes from the battery. By contrast, the low-current monitoring circuit, the logic control circuit, and any accompanying pacing output circuit of the ICD have peak battery demands in the microampere to milliampere range. The high power density batteries are typically regulated down to provide a stable low-current power supply to the monitoring and pacing control circuits over a wide range of potential battery loads. The down regulation of the power dense batteries is, however, an inefficient use of the depletable power source and thus a larger battery must be used to provide for the reliable operation of the ICD.
To resolve the dichotomy of combining high- and low-power circuits, the use of two separate batteries has been attempted. These “dual battery” systems provide two physically independent batteries matched to the separate power requirements of the ICD. U.S. Pat. Nos. 5,405,363 (Kroll et al.) and 5,439,482 (Adams et al.) describe the use of “dual battery” ICD systems. Each patent suggests that utilizing two batteries can result in a reduction of overall volume of the battery system as compared to a single battery system. While these patents describe reductions in ICD battery volumes, further reductions in battery volume and weight continue to be a goal of ICD designers.
SUMMARY OF THE INVENTION
The present battery system provides a dual battery system for use within an implantable medical device. The battery housings of the system share a common wall.
The shared common wall of the dual battery system reduces the weight and volume of the battery system, and thus the weight and volume of the implantable medical device. The result is a smaller, lighter, and more comfortable device for the patient.
The invention provides a battery system including (1) a unitary battery housing having a plurality of chambers; (2) a common wall between adjacent chambers; and (3) a plurality of batteries.
In one embodiment, the battery system has a unitary housing having at least two chambers, in which each pair of adjacent chambers share a common wall. Each chamber contains one battery, and at least one battery of the system has a different chemical composition than any or all of the remaining batteries.
In one application of the battery system, the battery is used in an ICD. The battery system comprises a unitary housing having a plurality of walls defining a first and a second chamber. The plurality of walls includes a common wall between the first chamber and the second chamber. Housed within the first chamber is a first electrochemical cell having a first cathode, a first anode, and a first electrolyte between the first cathode and the first anode. The second chamber houses a second cathode, a second anode, and a second electrolyte between the second cathode and the second anode. The two electrochemical cells have different chemical compositions such that one electrochemical cell can supply, for example, a energy dense low current output, in the microampere range, while the other electrochemical cell can supply a power dense high current output, in the ampere range. In this way the battery system can supply the distinct electrical needs of the various components of the implanted device while conserving both volume and weight of the implanted device.
In alternative embodiments, different numbers and locations of chambers can also be used to house the electrochemical cells. When only first and second chambers are used, they share an entire housing wall. However, when three or more chambers are used it is possible to have each chamber sharing a housing wall with more than one of the remaining chambers. In this way, further reductions in both volume and weight of the implanted device can be attained.
REFERENCES:
patent: 2212054 (1940-08-01), Spicer
patent: 3601601 (1971-08-01), Eilenberger
patent: 3918460 (1975-11-01), King et al.
patent: 3926198 (1975-12-01), Kolenik
patent: 4547894 (1985-10-01), Benson et al.
patent: 5370669 (1994-12-01), Daglow et al.
patent: 5405363 (1995-04-01), Kroll et al.
patent: 5439482 (1995-08-01), Adams et al.
patent: 5614331 (1997-03-01), Takeuchi et al.
patent: 3507092 (1986-08-01), None
patent: 0771576 (1997-05-01), None
patent: 0777286 (1997-06-01), None
Abstract of Japanese Patent Publication No. 59-018576 (Kubo), published on Jan. 30, 1984, from Patent Abstracts of Japan, vol. 008, No. 103 (E-244), 1 pg., (May 1984).
Maile Keith R.
Warren Jay A.
Cardiac Pacemakers Inc.
Maples John S.
Schwegan, Lundberg, Woessner & Kluth, P.A.
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