Abstract: A case for an implantable medical device includes a metal case portion, having an inside and an outside, configured to attach to at least one other case portion to define a biocompatible case for the implantable medical device. The metal case portion has a plurality of grooves disposed on at least one of the inside and the outside, the grooves being oriented substantially perpendicular to an expected direction of eddy currents produced by an inductive recharging coil in proximity thereto.

Abstract: A nerve overwrap for an implantable nerve stimulation system includes a flexible sheet of electrically insulative material, having an electrical resistivity of from about 108 ohm*m to about 1020 ohm*m, adapted to wrap substantially around a group of nerve stimulation electrodes.

Abstract: A lead for an implantable device includes a flexible, implantable tether, electrically connectable to an implantable device, and a plurality of control elements, disposed along the tether. The control elements are electrically interconnectable to the implantable device and configured to transmit one of power and communication signals thereto.

Abstract: A method for estimating capacity of a battery in an implantable medical device includes obtaining a characteristic curve of voltage versus resistance for the battery, periodically determining voltage and resistance of the battery, and comparing the resistance with a third derivative function of the characteristic curve, the third derivative function having roots representing near depletion of the battery and end of service of the battery, respectively. Remaining time of service of the battery can also be determined by comparing the resistance value with a curve of battery capacity versus resistance for the battery.

Abstract: A helical electrode for nerve stimulation includes an insulative helical substrate, having an inner surface, configured to wrap around a nerve. An electrical conductor is disposed upon the inner surface of the substrate. The conductor defines a helix of about one revolution and produces an electric field in which an injected current in similar axons varies by no more than about 25%. The conductor may include tapered end sections, which may be counter-tapered.

Abstract: Apparatus and methods for charging a power cell in an implantable medical device (“IMD”) are disclosed herein. In one embodiment, a method includes providing an electrical pulse to an inductor external to the IMD. A frequency of an oscillation signal induced in the inductor by the current pulse is measured. The inductor is driven with an oscillating signal having a frequency based on the measured frequency of the oscillation signal. The power cell is charged using current induced in the IMD by the driving of the inductor.

Abstract: A case for an implantable medical device includes a metal case portion, having an inside and an outside, configured to attach to at least one other case portion to define a biocompatible case for the implantable medical device. The metal case portion has a plurality of grooves disposed on at least one of the inside and the outside, the grooves being oriented substantially perpendicular to an expected direction of eddy currents produced by an inductive recharging coil in proximity thereto.

Abstract: A nerve overwrap for an implantable nerve stimulation system includes a flexible sheet of electrically insulative material, having an electrical resistivity of from about 108 ohm*m to about 1020 ohm*m, adapted to wrap substantially around a group of nerve stimulation electrodes.

Abstract: Apparatus and methods for charging a power cell in an implantable medical device (“IMD”) are disclosed herein. In one embodiment, a method includes providing an electrical pulse to an inductor external to the IMD. A frequency of an oscillation signal induced in the inductor by the current pulse is measured. The inductor is driven with an oscillating signal having a frequency based on the measured frequency of the oscillation signal. The power cell is charged using current induced in the IMD by the driving of the inductor.

Abstract: A method for estimating capacity of a battery in an implantable medical device includes obtaining a characteristic curve of voltage versus resistance for the battery, periodically determining voltage and resistance of the battery, and comparing the resistance with a third derivative function of the characteristic curve, the third derivative function having roots representing near depletion of the battery and end of service of the battery, respectively. Remaining time of service of the battery can also be determined by comparing the resistance value with a curve of battery capacity versus resistance for the battery.

Abstract: A lead for an implantable device includes a flexible, implantable tether, electrically connectable to an implantable device, and a plurality of control elements, disposed along the tether.

Abstract: A helical electrode for nerve stimulation includes an insulative helical substrate, having an inner surface, configured to wrap around a nerve. An electrical conductor is disposed upon the inner surface of the substrate. The conductor defines a helix of about one revolution and produces an electric field in which an injected current in similar axons varies by no more than about 25%. The conductor may include tapered end sections, which may be counter-tapered.