Abstract: A charging system for an Implantable Medical Device (IMD) is disclosed having a charging coil and one or more sense coils. The charging coil and one or more sense coils are preferably housed in a charging coil assembly coupled to an electronics module by a cable. The charging coil is preferably a wire winding, while the one or more sense coils are concentric with the charging coil and preferably formed in one or more traces of a circuit board. One or more voltages induced on the one or more sense coils can be used to determine the resonant frequency of the charging coil/IMD coupled system. The determined resonant frequency can then be used to determine the position of the charging coil relative to the IMD. The magnetic field produced from the charging coil may also be driven at the resonant frequency to optimize power transfer to the IMD.

Abstract: A charging system for an Implantable Medical Device (IMD) includes a split charging coil for generating a magnetic field to provide power to the IMD. The split charging coil includes a first coil portion and a second coil portion, each of which can be formed as a mechanical winding of an insulated conductor. The first and second coil portions are connected to each other in a way that substantially reduces or eliminates any current-carrying path that is routed radially with respect to the coil. As a result, the split coil produces a uniform magnetic field that enables a more accurate determination of alignment between the coil and the IMD than is available using traditional charging coils.

Abstract: A charging system for an Implantable Medical Device (IMD) is disclosed having a charging coil and one or more sense coils. The charging coil and one or more sense coils are preferably housed in a charging coil assembly coupled to an electronics module by a cable. The charging coil is preferably a wire winding, while the one or more sense coils are concentric with the charging coil and preferably formed in one or more traces of a circuit board. One or more voltages induced on the one or more sense coils can be used to determine whether the charging coil is (i) centered, (ii) not centered but not misaligned, or (iii) misaligned, with respect to the IMD being charged, which three conditions sequentially comprise lower coupling between the charging coil and the IMD. A charging algorithm is also disclosed that control charging dependent on these conditions.

Abstract: A charging system for an Implantable Medical Device (IMD) is disclosed having a charging coil and one or more sense coils preferably housed in a charging coil assembly coupled to an electronics module by a cable. The charging coil is preferably a wire winding, while the sense coils are preferably formed in one or more traces of a circuit board. One or more voltages induced on the one or more sense coils can be used to determine one or more parameters (magnitude, phase angle, resonant frequency) indicative of the position between the charging coil and the IMD, which position may include the radial offset and possibly also the depth of the charging coil relative to the IMD. Knowing the position, the power of the magnetic field produced by the charging coil can be adjusted to compensate for the position.

Abstract: A charging system for an Implantable Medical Device (IMD) is disclosed having a charging coil and one or more sense coils preferably housed in a charging coil assembly coupled to an electronics module by a cable. The charging coil is preferably a wire winding, while the sense coils are preferably formed in one or more traces of a circuit board. One or more voltages induced on the one or more sense coils can be used to determine a phase angle between the voltage and a driving signal for the charging coil. The determined phase angle can then be used to determine the position of the charging coil relative to the IMD. Additionally, more than one parameter (phase angle, magnitude, resonant frequency) may be determined using the voltage may be used to determine position, including the radial offset and depth of the charging coil relative to the IMD.

Abstract: An external charger for an implantable medical device (IMD) includes a multi-layer shield to direct the magnetic field generated by its charging coil towards the IMD. Each of the shield's multiple layers includes a ferromagnetic material that increases the permeance of the magnetic field's flux paths. The layers decrease in magnetic saturation point with increasing distance from the external charger's charging coil. That is, the layer closest to the charging coil has a higher saturation point than the next layer further from the charging coil, and so on. Layers that are positioned closer to the charging coil shield layers that are further from the charging coil, which generally have higher magnetic permeabilities, such that the magnetic intensity does not exceed any layer's saturation point. In this way, the multi-layer shield provides a beneficial balance between permeability and saturation, which can limit the required dimensions of the shield.

Abstract: A charging system for an Implantable Medical Device (IMD) is disclosed having a charging coil and one or more sense coils. The charging coil and one or more sense coils are preferably housed in a charging coil assembly coupled to an electronics module by a cable. The charging coil is preferably a wire winding, while the one or more sense coils are concentric with the charging coil and preferably formed in one or more traces of a circuit board. The magnitude of one or more voltages induced on the one or more sense coils can be measured to determine the position of the charging coil relative to the IMD, and in particular whether the charging coil is (i) centered, (ii) not centered but not misaligned, or (iii) misaligned, with respect to the IMD being charged, which three conditions sequentially comprise lower coupling between the charging coil and the IMD.

Abstract: A charging system for an Implantable Medical Device (IMD) is disclosed. The charging system features an electronics module connected to a charging coil by a cable. The charging system can be configured with a belt or harness that holds the charging coil position to charge the IMD and also providing a user with easy access to the electronics module. Resistance in the cable between electronics module and the charging coil is minimized by using multiple, individually insulated conductors to carry AC current.

Abstract: An implantable medical device (IMD) is disclosed having measurement circuitry for measuring one or more currents in the IMD, such as the currents drawn from various power supply voltages. Such currents are measured without disrupting normal IMD operation, and can be telemetered from the IMD for review. Switching circuitry in line with the current being measured is temporarily opened for a time period to disconnect the power supply voltage from the circuitry being powered. A voltage across a capacitance in parallel with the circuitry is measured when the switching circuitry is opened and again closed at the end of the time period, with the circuitry drawing power from the charged capacitance during this time period. The average current drawn by the power supply voltage is determined using the difference in the measured voltages, the known capacitance, and the time period between the measurements.

Abstract: An implantable medical device (IMD) is disclosed having measurement circuitry for measuring one or more currents in the IMD, such as the currents drawn from various power supply voltages. Such currents are measured without disrupting normal IMD operation, and can be telemetered from the IMD for review. Switching circuitry in line with the current being measured is temporarily opened for a time period to disconnect the power supply voltage from the circuitry being powered. A voltage across a capacitance in parallel with the circuitry is measured when the switching circuitry is opened and again closed at the end of the time period, with the circuitry drawing power from the charged capacitance during this time period. The average current drawn by the power supply voltage is determined using the difference in the measured voltages, the known capacitance, and the time period between the measurements.

Abstract: A neurostimulation device and system are provided. At least one neurostimulation lead having a plurality of electrodes is configured for being implanted within tissue of a patient. A shunt capacitance is coupled to one of the electrodes. Time-varying electrical current is delivered to at least one of the electrodes, wherein the shunt capacitance would, without compensation, absorb charge from or inject charge into the tissue in response to time-varying changes in the delivered electrical current, thereby causing an uncompensated electrical waveform to be delivered to the tissue adjacent the one electrode, The absorbed or injected charge is at least partially compensated for, thereby causing a compensated electrical waveform to be delivered to the tissue adjacent the one electrode.

Abstract: Receiver and digital demodulation circuitry for an external controller for communicating with an implantable medical device (IMD) is disclosed. A Digital Signal Processor (DSP) is used to sample received analog data transmitted from the IMD at a lower rate than would otherwise be required for the frequency components in the transmitted data by the Nyquist sampling criteria. To allow for this reduced sampling rate, the incoming data is shifted to a lower intermediate frequency using a switching circuit. The switching circuit receives a clock signal, which is preferably but not necessarily the same clock signal used by the DSP to sample the data. The switching circuit multiplies the received data with the clock signal to produce lower intermediate frequencies, which can then be adequately sampled at the DSP at the reduced sampling rate per the Nyquist sampling criteria.

Abstract: An implantable medical device (IMD) is disclosed having measurement circuitry for measuring one or more currents in the IMD, such as the currents drawn from various power supply voltages. Such currents are measured without disrupting normal IMD operation, and can be telemetered from the IMD for review. Switching circuitry in line with the current being measured is temporarily opened for a time period to disconnect the power supply voltage from the circuitry being powered. A voltage across a capacitance in parallel with the circuitry is measured when the switching circuitry is opened and again closed at the end of the time period, with the circuitry drawing power from the charged capacitance during this time period. The average current drawn by the power supply voltage is determined using the difference in the measured voltages, the known capacitance, and the time period between the measurements.

Abstract: An implantable control module for an electrical stimulation system includes a connector to couple to a lead or lead extension; an electronics housing coupled to the connector and having a first major surface, a second major surface, and at least one side surface; and an electronic subassembly disposed within the electronics housing. The electronics housing includes a first portion formed of a first conductive material and a second portion formed of a second conductive material. The second portion forms at least part of the first major surface and extends to form an adjacent region of the side surface or the second major surface. In some embodiments, the first conductive material has a resistivity that is no more than 50% of a resistivity of the second conductive material. In some embodiments, the first conductive material is titanium and the second conductive material is a titanium alloy.

Abstract: An implantable medical device (IMD) is disclosed having measurement circuitry for measuring one or more currents in the IMD, such as the currents drawn from various power supply voltages. Such currents are measured without disrupting normal IMD operation, and can be telemetered from the IMD for review. Switching circuitry in line with the current being measured is temporarily opened for a time period to disconnect the power supply voltage from the circuitry being powered. A voltage across a capacitance in parallel with the circuitry is measured when the switching circuitry is opened and again closed at the end of the time period, with the circuitry drawing power from the charged capacitance during this time period. The average current drawn by the power supply voltage is determined using the difference in the measured voltages, the known capacitance, and the time period between the measurements.

Abstract: An improved implantable medical device system having dual coils in one of the devices in the system is disclosed. The dual coils are used preferably in an external device such as an external controller or an external charger. The dual coils are wrapped around axes that are preferably orthogonal, although other non-zero angles could be used as well. When used to transmit, the two coils are driven (for example, with FSK-modulated data when the transmitting data) out of phase, preferably at 90 degrees out of phase. This produces a magnetic field which rotates, and which reduces nulls in the coupling between the external device and the receiving coil within the implanted device. Moreover, implementation of the dual coils to transmit requires no change in the receiver circuitry of the implanted device. Should the device with dual coils also receive transmissions from the other device (e.g.

Abstract: A neurostimulation device and system are provided. At least one neurostimulation lead having a plurality of electrodes is configured for being implanted within tissue of a patient. A shunt capacitance is coupled to one of the electrodes. Time-varying electrical current is delivered to at least one of the electrodes, wherein the shunt capacitance would, without compensation, absorb charge from or inject charge into the tissue in response to time-varying changes in the delivered electrical current, thereby causing an uncompensated electrical waveform to be delivered to the tissue adjacent the one electrode, The absorbed or injected charge is at least partially compensated for, thereby causing a compensated electrical waveform to be delivered to the tissue adjacent the one electrode.

Abstract: An implantable medical device (IMD) is disclosed having measurement circuitry for measuring one or more currents in the IMD, such as the currents drawn from various power supply voltages. Such currents are measured without disrupting normal IMD operation, and can be telemetered from the IMD for review. Switching circuitry in line with the current being measured is temporarily opened for a time period to disconnect the power supply voltage from the circuitry being powered. A voltage across a capacitance in parallel with the circuitry is measured when the switching circuitry is opened and again closed at the end of the time period, with the circuitry drawing power from the charged capacitance during this time period. The average current drawn by the power supply voltage is determined using the difference in the measured voltages, the known capacitance, and the time period between the measurements.

Abstract: Receiver and demodulation circuitry for an external controller for an implantable medical device is disclosed. The circuitry comprises two high Quality-factor band pass filters (BFPs) connected in series. Each BFP is tuned to a different center frequency, such that these center frequencies are outside the band of frequencies transmitted form the IMD. The resulting frequency response is suitably wide to receive the band without attenuation, but sharply rejects noise outside of the band. The resulting filtered signal is input to a comparator to produce a square wave of the filtered signal, which maintains the frequencies of the received signal and is suitable for input to a digital input of a microcontroller in the external controller. Demodulation of the square wave occurs in the microcontroller, and involves assessing the time between transitions in the square wave. These transmission timings are compared to expected transition times for the logic states in the transmitted data.

Abstract: Receiver and digital demodulation circuitry for an external controller for communicating with an implantable medical device (IMD) is disclosed. A Digital Signal Processor (DSP) is used to sample received analog data transmitted from the IMD at a lower rate than would otherwise be required for the frequency components in the transmitted data by the Nyquist sampling criteria. To allow for this reduced sampling rate, the incoming data is shifted to a lower intermediate frequency using a switching circuit. The switching circuit receives a clock signal, which is preferably but not necessarily the same clock signal used by the DSP to sample the data. The switching circuit multiplies the received data with the clock signal to produce lower intermediate frequencies, which can then be adequately sampled at the DSP at the reduced sampling rate per the Nyquist sampling criteria.