Diagnostic circuitry for monitoring charge states of electrodes of a lead system associated with an implantable pulse generator

Abstract

A system and method for measuring and monitoring charge states of one or more electrodes of an implanted stimulation lead system associated with an IPG. A Kelvin connection scheme operative with a switching circuit is provided for coupling select electrode terminals disposed in a Kelvin connection measurement loop in a switchable manner to sense and reference inputs of an analog-to-digital converter (ADC) configured as at least part of diagnostic circuitry for the IPG.

1 . A biostimulation system, comprising:
 an implantable medical device (IMD) including:
 a power supply module; 
 a processing unit; 
 a pulse generator; 
 an implantable lead system including at least one lead having a plurality of electrodes adapted to stimulate a patient's tissue responsive to instructions generated by the processing unit in association with the pulse generator; 
 diagnostic circuitry comprising an analog-to-digital converter (ADC) having a sense input and a reference input; and 
 switching circuitry operative to selectively couple one or more terminals associated with each electrode to the ADC of the diagnostic circuitry, the switching circuitry including one or more switches for each electrode corresponding to the one or more terminals associated therewith; and 
   an external programmer device disposed in a communicative relationship with the IMD, the external programmer device having a processor operative to execute program instructions responsive to user input, the program instructions for selectively actuating the switching circuitry of the IMD based on a selection of a particular Kelvin connection mode with respect to an active electrode and a Kelvin electrode, wherein the switching circuitry couples a terminal of the active electrode and a terminal of the Kelvin electrode, respectively, to the sense input and the reference input of the ADC for obtaining a voltage measurement indicative of a charge state associated with the active electrode.   
     
     
         2 . The biostimulation system as recited in  claim 1 , wherein the switching circuitry is selectively actuated responsive to the particular Kelvin connection mode such that a direct current (DC) blocking stimulation capacitor (C DC ) terminal of the active electrode is coupled to the sense input of the ADC and a DC blocking stimulation capacitor (C DC ) terminal of the Kelvin electrode is coupled to the reference input of the ADC. 
     
     
         3 . The biostimulation system as recited in  claim 1 , wherein the switching circuitry is selectively actuated responsive to the particular Kelvin connection mode such that a DC blocking stimulation capacitor (C DC ) terminal of the active electrode is coupled to the sense input of the ADC and an alternating current (AC) coupling sense capacitor (C SENSE ) terminal of the Kelvin electrode is coupled to the reference input of the ADC. 
     
     
         4 . The biostimulation system as recited in  claim 1 , wherein the switching circuitry is selectively actuated responsive to the particular Kelvin connection mode such that an AC coupling sense capacitor (C SENSE ) terminal of the active electrode is coupled to the sense input of the ADC and a DC blocking stimulation capacitor (C DC ) terminal of the Kelvin electrode is coupled to the reference input of the ADC. 
     
     
         5 . The biostimulation system as recited in  claim 1 , wherein the switching circuitry is selectively actuated responsive to the particular Kelvin connection mode such that an AC coupling sense capacitor (C SENSE ) terminal of the active electrode is coupled to the sense input of the ADC and an AC coupling sense capacitor (C SENSE ) terminal of the Kelvin electrode is coupled to the reference input of the ADC. 
     
     
         6 . The biostimulation system as recited in  claim 1 , wherein the external programmer device further includes program instructions for configuring the active electrode as one of a cathode to provide cathodic stimulation to the patient's tissue and an anode to provide anodic stimulation to the patient's tissue with respect to a particular therapy application. 
     
     
         7 . The biostimulation system as recited in  claim 6 , wherein the particular therapy application comprises a therapy selected from at least one of a spinal cord stimulation (SCS) therapy, a neuromuscular stimulation therapy, a dorsal root ganglion (DRG) stimulation therapy, a deep brain stimulation (DBS) therapy, a cochlear stimulation therapy, a drug delivery therapy, a cardiac pacemaker therapy, a cardioverter-defibrillator therapy, a cardiac rhythm management (CRM) therapy, an electrophysiology (EP) mapping and radio frequency (RF) ablation therapy, an electroconvulsive therapy (ECT), a repetitive transcranial magnetic stimulation (rTMS) therapy, and a vagal nerve stimulation (VNS) therapy. 
     
     
         8 . An implantable medical device (IMD) for biostimulation, the IMD including:
 a power supply module;   a processing unit;   a pulse generator;   an implantable lead system including at least one lead having a plurality of electrodes adapted to stimulate a patient's tissue responsive to instructions generated by the processing unit in association with the pulse generator;   switching circuitry operative to selectively couple one or more terminals associated with each electrode to an analog-to-digital converter (ADC) having a sense input and a reference input, the switching circuitry including one or more switches for each electrode corresponding to the one or more terminals associated therewith; and   diagnostic circuitry comprising the ADC operative for selectively actuating the switching circuitry based on a Kelvin connection mode with respect to an active electrode and a Kelvin electrode, wherein the switching circuitry couples a terminal of the active electrode and a terminal of the Kelvin electrode, respectively, to the sense input and the reference input of the ADC for obtaining a voltage measurement indicative of a charge state associated with the active electrode.   
     
     
         9 . The IMD as recited in  claim 8 , wherein the switching circuitry is selectively actuated responsive to the Kelvin connection mode such that a direct current (DC) blocking stimulation capacitor (C DC ) terminal of the active electrode is coupled to the sense input of the ADC and a DC blocking stimulation capacitor (C DC ) terminal of the Kelvin electrode is coupled to the reference input of the ADC. 
     
     
         10 . The IMD as recited in  claim 8 , wherein the switching circuitry is selectively actuated responsive to the Kelvin connection mode such that a DC blocking stimulation capacitor (C DC ) terminal of the active electrode is coupled to the sense input of the ADC and an alternating current (AC) coupling sense capacitor (C SENSE ) terminal of the Kelvin electrode is coupled to the reference input of the ADC. 
     
     
         11 . The IMD as recited in  claim 8 , wherein the switching circuitry is selectively actuated responsive to the Kelvin connection mode such that an AC coupling sense capacitor (C SENSE ) terminal of the active electrode is coupled to the sense input of the ADC and a DC blocking stimulation capacitor (C DC ) terminal of the Kelvin electrode is coupled to the reference input of the ADC. 
     
     
         12 . The IMD as recited in  claim 8 , wherein the switching circuitry is selectively actuated responsive to the Kelvin connection mode such that an AC coupling sense capacitor (C SENSE ) terminal of the active electrode is coupled to the sense input of the ADC and an AC coupling sense capacitor (C SENSE ) terminal of the Kelvin electrode is coupled to the reference input of the ADC.