Optimization of application of current
Apparatus is provided, comprising: (a) an implantable excitation unit, configured to induce action potentials in a nerve of a subject by applying an excitatory current; (b) an implantable blocking unit, configured to block the induced action potentials from propagating along the nerve by applying a blocking current; and (c) an extracorporeal controller, comprising circuitry configured: (i) to wirelessly drive the excitation unit to apply the excitatory current, (ii) in a first mode, to wirelessly drive the blocking unit to apply the blocking current while not driving the excitation unit to apply the excitatory current, (iii) in a second mode, to wirelessly drive the blocking unit to apply the blocking current while driving the excitation unit to apply the excitatory current, and (iv) to wirelessly alter a parameter of the blocking current, based on sensing performed while the extracorporeal controller is in the second mode.
1. Apparatus, for use with a nerve of a subject, the apparatus comprising:
an implantable excitation unit, including an excitation-unit electrode, and configured to induce action potentials in the nerve by driving the excitation-unit electrode to apply an excitatory current to the nerve;
an implantable blocking unit, including a blocking-unit electrode, and configured to block the induced action potentials from propagating along the nerve by driving the blocking-unit electrode to apply a blocking current to the nerve;
an implantable sensor unit:
configured to detect the induced action potentials in the nerve,
including a sensor unit antenna, and
configured to provide, via the sensor unit antenna, and in response to detecting the induced action potentials in the nerve, a sensor signal that conveys information about the detected induced action potentials; and
an extracorporeal controller, programmed with a first mode and a second mode, and comprising (i) at least one controller antenna, and (ii) circuitry configured to, via the at least one controller antenna:
wirelessly drive the excitation unit to apply the excitatory current,
in the first mode of the extracorporeal controller, wirelessly drive the blocking unit to apply the blocking current while not driving the excitation unit to apply the excitatory current, and
in the second mode of the extracorporeal controller, wirelessly drive the blocking unit to apply the blocking current while driving the excitation unit to apply the excitatory current,
wherein the circuitry is programmed with a calibration routine, and is configured to automatically periodically run the calibration routine, the calibration routine comprising:
(a) switching the extracorporeal controller into the second mode,
(b) via the at least one controller antenna, wirelessly receiving the sensor signal, the sensor signal conveying information about induced action potentials detected while the extracorporeal controller is in the second mode,
(c) in response to the sensor signal received in step (b) of the calibration routine, wirelessly altering a parameter of the blocking current, and
(d) switching the extracorporeal controller into the first mode.
2. The apparatus according to claim 1 , wherein the extracorporeal controller is programmed with a third mode, in which the circuitry is configured to wirelessly drive the excitation unit to apply the excitatory current while not driving the blocking unit to apply the blocking current.
3. The apparatus according to claim 1 , wherein the excitatory current has a frequency of 2-400 Hz, and the circuitry is configured to wirelessly drive the excitation unit to apply the excitatory current having the frequency of 2-400 Hz.
4. The apparatus according to claim 3 , wherein the excitatory current has a frequency of 5-100 Hz, and the circuitry is configured to wirelessly drive the excitation unit to apply the excitatory current having the frequency of 5-100 Hz.
5. The apparatus according to claim 1 , wherein the blocking current has a frequency of 1-20 kHz, and the circuitry is configured to wirelessly drive the blocking unit to apply the blocking current having the frequency of 1-20 kHz.
6. The apparatus according to claim 5 , wherein the blocking current has a frequency of 3-10 kHz, and the circuitry is configured to wirelessly drive the blocking unit to apply the blocking current having the frequency of 3-10 kHz.
7. The apparatus according to claim 1 , further comprising an implantable device that comprises a housing that houses the excitation unit, the blocking unit, and the sensor unit.
8. The apparatus according to claim 1 , wherein the extracorporeal controller is programmed with a third mode, in which the circuitry is configured to wirelessly drive the excitation unit to apply the excitatory current while not driving the excitation unit to apply the blocking current, and wherein the calibration routine further comprises, prior to step (a)
(i) switching the extracorporeal controller into the third mode, and
(ii) receiving the sensor signal, the sensor signal conveying information about induced action potentials detected while the extracorporeal controller is in the third mode.
9. The apparatus according to claim 8 , wherein step (c) of the calibration routine comprises altering the parameter of the blocking current in response to the sensor signal received in step (b) of the calibration routine, and in response to the sensor signal received in step (ii) of the calibration routine.
10. The apparatus according to claim 1 , wherein the extracorporeal controller further comprises a user interface, and wherein the circuitry is configured to switch the extracorporeal controller between the first and second modes in response to user operation of the user interface.