Implantable stimulator that prevents DC current flow without the use of discrete output coupling capacitors
First Claim
1. An implantable living tissue stimulator comprising:
- a case having a plurality of feed-through terminals;
first circuit means inside of the case for generating a stimulating current pulse; and
second circuit means within the case for providing an electrical current path between the first circuit means and a selected pair of the plurality of feed-through terminals through which the stimulating current pulse must pass, and for blocking dc current flow through the electrical current path;
said second circuit means comprising a plurality of circuit elements that do not include a coupling capacitor and do not include a coupling transformer in the electrical current path.
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Accused Products
Abstract
An implantable living tissue stimulator avoids the use of conventional coupling capacitors in its output stage, yet still prevents an average dc current flow from flowing through living tissue in electrical contact with the stimulator. The output stage generates and applies a biphasic stimulating current pulse to selected paired output terminals. The terminals, in turn, are electrically connected to respective electrodes which are positioned so as to contact the living tissue to be stimulated. In one embodiment, special circuitry is employed within the output stage to block dc current flow through the living tissue and to balance the electrical charge that is delivered to the living tissue. In another embodiment, the electrodes themselves are made from a material that allows them to function as a capacitor. In yet an additional embodiment, the coupling capacitors are integrated into the leads that connect the output terminals of the output stage with the electrodes.
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Citations
38 Claims
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1. An implantable living tissue stimulator comprising:
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a case having a plurality of feed-through terminals; first circuit means inside of the case for generating a stimulating current pulse; and second circuit means within the case for providing an electrical current path between the first circuit means and a selected pair of the plurality of feed-through terminals through which the stimulating current pulse must pass, and for blocking dc current flow through the electrical current path; said second circuit means comprising a plurality of circuit elements that do not include a coupling capacitor and do not include a coupling transformer in the electrical current path. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. An implantable living tissue stimulator comprising:
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a biphasic current pulse generator; and output circuit means for receiving a biphasic current pulse generated by the biphasic current pulse generator and directing such biphasic current pulse along an electrical current path to a selected pair of a plurality of output terminals; said output circuit means comprising prevention means for preventing an average dc current flow through the electrical current path, said prevention means comprising a plurality of circuit elements that do not include a coupling capacitor in the electrical current path. - View Dependent Claims (26, 27, 28, 29)
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30. An implantable living tissue stimulator comprising:
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biphasic current pulse generator means for generating a series of biphasic current pulses; output circuit means for receiving a biphasic current pulse generated by the biphasic current pulse generator means and directing such biphasic current pulse along an electrical current path to a selected pair of a plurality of output terminals; an electrode array comprising a plurality of electrodes, each electrode of said plurality of electrodes being connected to one of the plurality of output terminals, a selected pair of said plurality of electrodes thereby having the biphasic current pulse applied thereto; and means for preventing dc current flow, without output coupling capacitors or output coupling transformers, through the selected pair of said plurality of electrodes of said electrode array. - View Dependent Claims (31, 32, 33, 34, 35, 36)
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37. A method of stimulating living tissue with a stream of biphasic stimulation current pulses while preventing an average dc current flow from flowing through the living tissue, said method comprising:
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generating a series of biphasic stimulation current pulses; applying the series of biphasic stimulation pulses to an electrical current path that includes an electrode pair in contact with the living tissue; and cancelling dc current flow in the electrical current path by; sensing any dc current flow in the electrical current path having a time constant associated therewith that is longer than the biphasic stimulation current pulse, generating an offsetting current that is equal to but opposite in polarity from the sensed dc current flow, and injecting the offsetting current into the electrical current path.
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38. A method of stimulating living tissue with a stream of biphasic stimulation current pulses while preventing an average dc current flow from flowing through the living tissue, said method comprising:
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generating a series of biphasic stimulation current pulses; applying the series of biphasic stimulation pulses to an electrical current path that includes an electrode pair in contact with the living tissue; and blocking dc current flow in the electrical current path by; sensing any dc current flow in the electrical current path having a time constant associated therewith that is longer than the biphasic stimulation current pulse, comparing the sensed dc current to a prescribed threshold level, and disrupting the electrical current path to the tissue whenever the sensed dc current exceeds the prescribed threshold level.
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Specification