Multichannel implantable cochlear stimulator having programmable bipolar, monopolar or multipolar electrode configurations

• US 5,531,774 A
• Filed: 10/12/1994
• Issued: 07/02/1996
• Est. Priority Date: 09/22/1989
• Status: Expired due to Term

• Current Assignee: Alfred E. Mann Foundation For Scientific Research
• Original Assignee: Alfred E. Mann Foundation For Scientific Research
• Inventors: Schulman, Joseph H., Gord, John C., Wolfe, James H., Strojnik, Primoz, Whitmoyer, David I.
• Primary Examiner(s): Kamm, William E.
• Assistant Examiner(s): LAYNO, CARL HERNANDZ
• Application Number:
  US08/322,065
• Time in Patent Office: 629 Days
• Field of Search: 607/55, 607/56, 607/57, 607/5, 607/8
• US Class Current: 607/56
• CPC Class Codes: A61N 1/36038 Cochlear stimulation
• CPC Class Codes: A61N 1/36185 Selection of the electrode configuration
• CPC Class Codes: A61N 1/37252 Details of algorithms or data aspects of communication system, e.g. handshaking, transmitting specific data or segmenting data
• CPC Class Codes: H04R 2460/03 Aspects of the reduction of energy consumption in hearing devices
• CPC Class Codes: H04R 25/505 using digital signal processing

Abstract

An implantable cochlear stimulator (ICS) has eight output stages (212), each having a programmable current source (212B) connected to a pair of electrodes, designated "A" and "B", through respective output coupling capacitors and an electrode switching matrix (212C). An indifferent electrode is connected to each output stage by way of an indifferent electrode switch (212D). An output mode register (208) controls the switching matrix of each stage, as well as the indifferent electrode switch, to configure the electrodes for: (1) bipolar stimulation (current flow between the pair of electrodes of the output stage), (2) monopolar A stimulation (current flow between the "A" electrode of the output stage and the indifferent electrode), (3) monopolar B stimulation (current flow between the "B" electrode of the output stage and the indifferent electrode), or (4) multipolar stimulation (current flow between the "A" or "B" electrode of one output stage and the "A" or "B" electrode of another output stage). The mode register is set by way of a command word, transmitted to the ICS from an external wearable system (10) as part of a data frame. The voltage at the "A" and "B" electrode of each output stage may be selectively telemetered to the wearable system, as may the current flow through the indifferent electrode, thereby facilitating a measurement of the electrode impedance. The "A" and "B" electrodes of each output stage may be selectively shorted through a high or low resistance in order to discharge the output coupling capacitors.

Claims

1. A multichannel implantable cochlear stimulator (ICS) for use with an external wearable processor (WP) system, said ICS comprising:

receiver means for receiving a data signal from the WP, the data signal comprising a series of data frames containing an end of frame signal, each data frame comprising a plurality of data words, each data word defining an amplitude for an output stimulation current for a different output channel of the ICS, and a command word for controlling a processor means in the ICS;

power supply means coupled to said receiver means for extracting a raw power signal from the data signal and generating a plurality of power signals therefrom that provide operating power to the ICS;

a multiplicity of output stages within said ICS, one for each of a multiplicity of output channels provided by said ICS, with each output stage having an "A" and a "B" stimulating electrode connected thereto;

indifferent electrode switch means within said ICS for connecting an indifferent electrode to each output stage;

processor means coupled to said receiver means, multiplicity of output stages, and power supply means for serially processing the plurality of data words and command word in each data frame received by the receiver means, said processor means comprising;

command detector means responsive to the command words for controlling the functions of the processor means, including setting an electrode configuration in each output stage of the ICS,

data word latching means for successively storing the data words,

switch means for successively generating and coupling a signal voltage representative of the output stimulation signal defined by the data word stored by the data word latching means to successive ones of the multiplicity of output stages; and

wherein

each of the multiplicity of output stages is contained within the ICS, is powered by the power signals generated by the power supply means, and includes;

refresh voltage controller means for generating an isolated refresh voltage for the output channel,

a voltage controlled current source powered by the isolated refresh voltage controller means for amplitude controlling, in accordance with the signal voltages coupled from the switch means, an output stimulation current,

electronic switching matrix means responsive to the command detector means for configuring the "A" and "B" electrodes of each output stage, and the indifferent electrode, in a selected one of at least the following four electrode configurations;

(1) bipolar stimulation, wherein the output stimulation current flows between the "A" and "B" electrodes of the output stage, (2) monopolar A stimulation, wherein the output stimulation current flows between the "A" electrode of the output stage and the indifferent electrode, (3) monopolar B stimulation, wherein the output stimulation current flows between the "B" electrode of the output stage and the indifferent electrode, and (4) multipolar stimulation, wherein the output stimulation current flows between the "A" or "B" electrode of one output stage and the "A" or "B" electrode of another output stage.

2. The multichannel ICS of claim 1 wherein the number of output stages comprises eight, each having its own "A" and "B" electrode connected thereto.

3. The multichannel ICS of claim 1 wherein the ICS further includes telemetry means for transmitting a backtelemetry signal to the WP, said telemetry means comprising:

carrier means for generating a telemetry carrier signal,

decoder means coupled to the command detector means for generating a multiplexer control signal as a function of information received within the command word of the data frame,

multiplexer means for selecting one of a plurality of ICS status signals as a function of the multiplexer control signal, said ICS status signals including output voltages at the "A" and "B" electrodes of each output stage,

modulator means for modulating the telemetry carrier signal with the ICS status signal selected by the telemetry multiplexer means;

whereby ICS status information may be selectively telemetered back to the WP.

4. The multichannel ICS of claim 3 wherein said indifferent electrode switch means includes means for inserting a first resistor in series with the indifferent electrode, and wherein the plurality of ICS status signals includes a first voltage developed across said first resistor, which first voltage provides an indication of the stimulating current flowing through the indifferent electrode, whereby the ICS status information telemetered back to the WP may include an output voltage and a stimulating current for monopolar A and monopolar B electrode configurations, from which ICS status information a determination of electrode impedance may be calcuated.

5. The multichannel ICS of claim 4 wherein the indifferent electrode switch means further includes means for inserting a second resistor, having a resistance higher than the first resistance, in series with the indifferent electrode, whereby stimulating currents of a low amplitude may be more readily determined.

6. The multichannel ICS of claim 1 wherein each of the "A" and "B" stimulating electrodes are connected to their respective output stage through an output coupling capacitor, and wherein each output stage includes shorting means for selectively shorting the "A" and "B" electrodes through a resistor in order to discharge the output coupling capacitor.

7. The multichannel ICS of claim 6 wherein the shorting means of each output stage includes means for selectively shorting the "A" and "B" electrodes through a selected one of either a high resistance or a low resistance in order to control the discharge time of the output coupling capacitor.

8. The multichannel ICS of claim 7 wherein the high resistance used to short the "A" and "B" electrodes of each output stage comprises a resistance of at least 150K ohms.

9. The multichannel ICS of claim 1 wherein the output stage of each channel includes means for responding to a ZERO command, corresponding to a zero amplitude data word of a prescribed polarity in the data frame received from the WP, in a way that places the output stage in an open state, such that the "A" and "B" electrodes of that output stage electrically float relative to each other.

10. The multichannel ICS of claim 1 wherein the multipolar electrode configuration includes means for configuring a first and a second output stage in a monopolar configuration, and means for disconnecting the indifferent electrode using the indifferent electrode switch, whereby current flows between one of the "A" or "B" electrodes of the first output stage and one of the "A" or "B" electrodes of the second output stage.

13. The multichannel ICS of claim 3 wherein said indifferent electrode switch means includes means for inserting a first resistor in series with the indifferent electrode, and wherein the plurality of ICS status signals includes a first voltage developed across said first resistor, which first voltage provides an indication of the stimulating current flowing through the indifferent electrode, whereby the ICS status information telemetered back to the WP may include an output voltage and a stimulating current for monopolar A and monopolar B electrode configurations, from which ICS status information a determination of electrode impedance may be calcuated.

11. A multichannel implantable cochlear stimulator (ICS) for use with an external wearable processor (WP) comprising:

a multiplicity of output stages, one for each of a multiplicity of output channels provided by said ICS, with each output stage having an "A" and a "B" stimulating electrode connected thereto;

indifferent electrode switch means coupled to said multiplicity of output stages for connecting an indifferent electrode to each output stage;

processor means coupled to said multiplicity of output stages and indifferent electrode switch means for controlling the functions of the ICS, including setting an electrode configuration in each output stage of the ICS;

current source means coupled to said multiplicity of output stages and indifferent electrode for generating a precise stimulation current pulse that is applied between a first electrode and a second electrode of said ICS, said first and second electrodes belonging to a group of electrodes that comprises the "A" and "B" electrodes of each of said multiplicity of output stages and said indifferent electrode; and

electronic switching matrix means included within each of said multiplicity of output stages and coupled to said current source means, and responsive to control signals generated by the processor means, for configuring the "A" and "B" electrodes of each output stage and the indifferent electrode in a selected one of at least the following four electrode configurations;

(1) bipolar stimulation, wherein the output stimulation current pulse flows between the "A" and "B" electrodes of the output stage, (2) monopolar A stimulation, wherein the output stimulation current pulse flows between the "A" electrode of the output stage and the indifferent electrode, (3) monopolar B stimulation, wherein the output stimulation current pulse flows between the "B" electrode of the output stage and the indifferent electrode, and (4) multipolar stimulation, wherein the output stimulation current pulse flows between the "A" or "B" electrode of one output stage and the "A" or "B" electrode of another output stage.

12. The multichannel ICS of claim 11 wherein the ICS further includes telemetry means for transmitting a backtelemetry signal to the WP, said telemetry means comprising:

carrier means for generating a telemetry carrier signal,

means for generating a multiplexer control signal,

multiplexer means for selecting one of a plurality of ICS status signals as a function of the multiplexer control signal, said ICS status signals including output voltages at the "A" and "B" electrodes of each output stage,

modulator means for modulating the telemetry carrier signal with the ICS status signal selected by the telemetry multiplexer means;

whereby ICS status information may be selectively telemetered back to the WP.

14. The multichannel ICS of claim 11 wherein each of the "A" and "B" stimulating electrodes are connected to their respective output stage through an output coupling capacitor, and wherein each output stage includes shorting means for selectively shorting the "A" and "B" electrodes through a resistor in order to discharge the output coupling capacitor.

15. The multichannel ICS of claim 14 wherein the shorting means of each output stage includes means for selectively shorting the "A" and "B" electrodes through a selected one of either a high resistance or a low resistance in order to control the discharge time of the output coupling capacitor.

16. The multichannel ICS of claim 15 wherein the high resistance used to short the "A" and "B" electrodes of each output stage comprises a resistance of at least 150K ohms.