A system for treating chronic inflammation may include an implantable microstimulator, a wearable charger, and optionally an external controller. The implantable microstimulator may be implemented as a leadless neurostimulator implantable in communication with a cervical region of a vagus nerve. The microstimulator can address several types of stimulation including regular dose delivery. The wearable charger may be worn around the subject's neck to rapidly (<10 minutes per week) charge an implanted microstimulator. The external controller may be configured as a prescription pad that controls the dosing and activity of the microstimulator.

A method for controlling electrical conditions of tissue in relation to a current stimulus. A first current produced by a first current source is delivered to the tissue via a current injection electrode. A second current drawn by a second current source is extracted from the tissue via a current extraction electrode. The second current source is matched with the first current source so as to balance the first current and the second current. A ground electrode which is proximal to the current injection electrode and the current extraction electrode is grounded, to provide a ground path for any mismatch current between the first current and second current. A response of the tissue to the current stimulus is measured via at least one measurement electrode.

In electrically stimulating neural tissue it is important to prevent over stimulation and unbalanced stimulation, which would cause damage to the neural tissue, the electrode, or both. It is critical that neural tissue is not subjected to any direct current or alternating current above a safe threshold. Further, it is important to identify defective electrodes, as continued use may result in neural damage and further electrode damage. The present invention presents system and stimulator control mechanisms to prevent damage to neural tissue.

A neuromodulation system and method with feedback optimized electrical field generation for stimulating target tissue of a patient to treat neurological and non-neurological conditions. The system generally includes implantable electrodes, implantable sensors, an implantable or external electrical signal generator, and an implantable or external controller. The controller controls the electrical signal generator to generate electrical noise stimulation signals that are delivered to the target tissue via the electrodes and that produce an optimized electric field having maximized voltage with low current density. The sensors produce temperature and impedance data for the target tissue and the controller automatically responds to values of the sensor data that indicate potential damage to the target tissue to reduce the strength of the electric field.

A system for providing biphasic stimulation is disclosed. The system includes an electrode, an antenna coupled to a transmitter, a capacitor, a power supply, a backscatter load selectively coupled to the antenna via a switching device, a plurality of switches, and a controller configured to control the switching device to output, by the antenna, an acknowledgement signal to the transmitter responsive to receiving the power. The controller is further configured to control the plurality of switches to electrically couple a first plate of the capacitor to the electrode to provide a first nerve stimulation signal having a first polarity, and electrically couple a second plate of the capacitor to the electrode to provide a second nerve stimulation signal having a second polarity opposite the first polarity. The system further includes a housing encapsulating the antenna, the capacitor, the power supply, the backscatter load, the switches, and the controller.

One aspect of the present disclosure relates to a system that can prevent unintended signal components (noise) in an electric waveform that can be used for at least one of neural stimulation, block, and/or sensing. The system can include a signal generator to generate a waveform that includes an intended electric waveform and unintended noise. The system can also include a signal transformer device (e.g., a very long wire) comprising a first coil and a second coil. The first coil can be coupled to the signal generator to receive the waveform and remove the unintended noise from the electric waveform. The second coil can pass the electric waveform to an electrode. The second coil can be coupled to a capacitor that can prevent the waveform from developing noise at an electrode/electrolyte interface between an electrode and a nerve.

One or more antennas are electrically coupled to one or more switches of an implantable medical device (IMD) in which the one or more switches are additionally electrically coupled to one or more lead wires of an IMD lead. The one or more switches also are electrically coupled to one or more electrodes or electrical circuitry of the IMD's implantable pulse generator (IPG). In response to exposure of the IMD to an energetic electromagnetic field, a voltage signal is induced in the one or more antennas and provided, possibly via one more filters, as a control signal to the one or more switches. Receipt of the control signal by the one or more switches automatically configures the one or more switches into a non-conductive state, thereby electrically isolating the one or more lead wires from the one or more electrodes or the IPG electrical circuitry.

In one embodiment, an implantable pulse generator (IPG) for providing a neurostimulation therapy, comprises: pulse generation circuitry and pulse delivery circuitry for controlling generation and delivery of electrical pulses to a patient using one or more electrodes of a stimulation lead; measurement circuitry for determining characteristics of one or more electrodes selected for delivery of electrical pulses; and a processor for controlling the IPG according to executable code; wherein the IPG is adapted to calculate values for an impedance model of the one or more selected electrodes using the determined plurality of voltage measurements and to adjust current levels for the exponentially decreasing current pattern based on the calculated values for the impedance mode.

System and methods for detecting impedance changes and for adjusting electrical therapy based on impedance changes are disclosed herein. A method in accordance with a particular embodiment includes applying a therapeutic, paresthesia-less electrical signal to a patient via a patient modulation system that includes a signal delivery device in electrical communication with a target neural population of the patient. The method can include monitoring on a periodic basis an impedance of an electrical circuit that includes the signal delivery device. The method can further include detecting a change in the impedance that indicates a fault and providing an indication that the fault exists.

A stimulation system stimulates anatomical targets in a patient for treatment of dry eye. The system may include a controller and a microstimulator. The controller may be implemented externally to or internally within the microstimulator. The components of the controller and microstimulator may be implemented in a single unit or in separate devices. When implemented separately, the controller and microstimulator may communicate wirelessly or via a wired connection. The microstimulator may generate pulses from a controller signal and apply the signal via one or more electrodes to an anatomical target. The microstimulator may not have any intelligence or logic to shape or modify a signal. The microstimulator may be a passive device configured to generate a pulse based on a signal received from the controller. The microstimulator may shape or modify a signal. Waveforms having different frequency, amplitude and period characteristics may stimulate different anatomical targets in a patient.