Cochlear implant systems can include a cochlear electrode and a stimulator in electrical communication with the cochlear electrode. The stimulator can be in communication with a controller, which is in communication with a testing circuit and a switching network. The stimulator can include a plurality of source elements. The controller can control the switching network to place the plurality of source elements into communication with the testing circuit. The controller can further cause one of the plurality of source elements to emit an electrical current and can determine an amount of electrical current emitted from the source element using the testing circuit. The controller can compare the determined amount of electrical current emitted by the source element with a prescribed current. The controller can adjust the output of each of the plurality of source elements based on the determined amount of electrical current emitted by the stimulator.

Systems and methods for active charge-balancing for high frequency neural stimulation are disclosed. One illustrative method described herein includes: applying, through a pair of electrodes electrically coupled to a bundle of nerve fibers during a stimulation phase of a neural stimulation procedure, a first current to the bundle of nerve fibers; applying, through the pair of electrodes during a recovery phase of the neural stimulation procedure, a second current to the bundle of nerve fibers, the first current and the second current having opposite polarities; determining sampled voltages between the pair of electrodes during the stimulation phase, during the recovery phase, or between the stimulation phase and the recovery phase; determining a charge buildup in the bundle of nerve fibers based on the sampled voltages; applying, through the pair of electrodes during the stimulation phase or during the recovery phase, a delta current to the bundle of nerves based on the sampled voltages to minimize the charge build up.

A method for estimating an offset between a first group and a second group of contacts with respect to a longitudinal direction. Each group of contacts includes a plurality of electrodes arranged along a surface of a body of a lead. The method includes the steps of: (a) Selecting a number of electrode pairs, each electrode pair including an electrode of the first contact group and an electrode of the second contact group, and measuring the impedances between the electrodes of each selected electrode pair; (b) pre-conditioning the measured impedances for attenuating unwanted noise to generate pre-conditioned impedances, and (c) determining the lead offset using the pre-conditioned impedances.

Improved stimulation circuitry for controlling the stimulation delivered by an implantable stimulator is disclosed. The stimulation circuitry includes memory circuitry that stores pulse programs that define pulse shapes, steering programs that define electrode configurations, and aggregate programs that link a selected pulse program with a selected steering program. The aggregate programs also include an amplitude modulation factor that modulates the amplitude defined by the pulse program. The inclusion of an amplitude modulation factor in the aggregate program allows complex amplitude-modulated waveforms to be produced. Pulse definition circuits in the stimulation circuitry execute aggregate programs to generate stimulation waveforms, which stimulation waveforms can be generated simultaneously by the different pulse definition circuits.

A wireless charger system for inductively charging a rechargeable battery of an implantable pulse generator (IPG) implanted in a human body is provided. A charging coil in the charger is wirelessly coupled to a receiving coil of the IPG to charge the rechargeable battery. An end-of-charge (EOC) circuit continuously monitors the reflected impedance from a reflected impedance sensor and determines the end of charge when a predetermined pattern of the reflected impedance corresponding to an EOC signal from the IPG is received. Advantageously, receiving the EOC signal through the charging coil eliminates the need to provide a separate communication circuit in the IPG that communicates with the charger.

A medical apparatus for an organ has a substrate that conforms to a shape of the organ, and a plurality of processing units connected to the substrate and distributed throughout the substrate. Each of the processing units has a sensor, processing device and actuator. The sensor senses a condition of the organ and provides a sensed signal. The processing device receives the sensed signal from said sensor, analyzes the sensed signal and provides a control signal. The actuator applies an output pulse to the organ in response to the control signal from the processing device.

An Implantable Pulse Generator (IPG) is disclosed that is capable of sensing a degree to which recruited neurons in a patient's tissue are firing synchronously, and of modifying a stimulation program to promote desynchronicity and to reduce paresthesia. An evoked compound action potential (ECAP) of the recruited neurons is sensed as a measure of synchronicity by at least one non-active electrode. An ECAP algorithm operable in the IPG assesses the shape of the ECAP and determines one or more ECAP shape parameters that indicate whether the recruited neurons are firing synchronously or desynchronously. If the shape parameters indicate significant synchronicity, the ECAP algorithm can adjust the stimulation program to promote desynchronous firing.

A method and apparatus for measuring a bioimpedance and performing an electrical stimulation is provided. The method includes generating a first current corresponding to a first high-frequency, generating a second current corresponding to a second high-frequency, generating a low-frequency current based on a beat phenomenon of the first current and the second current, and calculating an impedance of a target part based on a voltage induced to the target part by a high-frequency current corresponding to at least one of the first current and the second current and the low-frequency current.

Sense amplifier circuits particularly useful in sensing neural responses in an Implantable Pulse Generator (IPG) are disclosed. The IPG includes a plurality of electrodes, with one selected as a sensing electrode and another selected as a reference to differentially sense the neural response in a manner that subtracts a common mode voltage (e.g., stimulation artifact) from the measurement. The circuits include a differential amplifier which receives the selected electrodes at its inputs, and comparator circuitries to assess each differential amplifier input to determine whether it is of a magnitude that is consistent with the differential amplifier's input requirements. Based on these determinations, an enable signal is generated which informs whether the output of the differential amplifier validly provides the neural response at any point in time. Further, clamping circuits are connected to the differential amplifier inputs to clamp these inputs in magnitude to prevent the differential amplifier from damage.

A group select matrix is added to an implantable stimulator device to allow current sources to be dedicated to particular groups of electrodes at a given time. The group select matrix can time multiplex the current sources to the different groups of electrodes to allow therapy pulses to be delivered at the various groups of electrodes in an interleaved fashion. Each of the groups of electrodes may be confined to a particular electrode array implantable at a particular non-overlapping location in a patient's body. A switch matrix can be used in conjunction with the group select matrix to provide further flexibility to couple the current sources to any of the electrodes.