US-12623081-B2 - Differential charge-balancing during high-frequency neural stimulation

Abstract

Differential charge-balancing can be used in high-frequency neural stimulation. For example, a neural stimulation apparatus can have first and second electrodes configured to be coupled proximate to a nerve fiber to implement a neural stimulation procedure. A neural stimulation circuit can be electrically coupled to the first and second electrodes. The neural stimulation circuit can apply stimulation currents to the nerve fiber through the first and second electrodes during a first stimulation phase of the neural stimulation procedure. The neural stimulation circuit can also apply a modified stimulation current to the nerve fiber through the first electrode during a second stimulation phase of the neural stimulation procedure. The modified stimulation current can be generated based on a difference between (i) a voltage at the first electrode, and (ii) a reference voltage derived from voltages on the first and second electrodes.

Inventors

• James SALVIA
• Meisam Heidarpour Roshan

Assignees

• Verily Health Inc.

Dates

Publication Date

20260512

Application Date

20221213

Claims (20)

1. 1 . A method comprising: applying, by a current source of a neural stimulation apparatus, a stimulation current to a nerve fiber through a set of electrodes during a first stimulation phase of a neural stimulation procedure; and applying, by the current source of the neural stimulation apparatus, a modified stimulation current to the nerve fiber through the set of electrodes during a second stimulation phase of the neural stimulation procedure, wherein the modified stimulation current is generated based on a voltage difference between (i) a voltage at a first electrode in the set of electrodes, and (ii) a reference voltage derived from voltages at the first electrode and a second electrode in the set of electrodes.
2. 2 . The method of claim 1 , further comprising applying the stimulation current to the nerve fiber through a third electrode during the first stimulation phase of the neural stimulation procedure.
3. 3 . The method of claim 2 , wherein the reference voltage is derived from voltages at the first electrode, the second electrode, and the third electrode.
4. 4 . The method of claim 1 , further comprising adjusting one of more characteristics of the stimulation current to generate the modified stimulation current by: generating a signal based on the voltage difference; and supplying the signal to the current source, the current source being configured to receive the signal and adjust one or more characteristics of the stimulation current based on the signal.
5. 5 . The method of claim 4 , wherein: the one or more characteristics include an amplitude, a wave shape, or a duration; and the reference voltage is an average voltage among the set of electrodes.
6. 6 . The method of claim 4 , wherein the first electrode is electrically coupled to the second electrode at a common node to produce the reference voltage at the common node, wherein a sampling capacitor is electrically coupled between the common node and the first electrode, and further comprising: charging the sampling capacitor to a voltage, wherein the voltage represents the voltage difference between the first electrode's voltage and the reference voltage; and generating the signal based on the voltage at the sampling capacitor.
7. 7 . The method of claim 6 , wherein: the signal is generated by a voltage-to-current converter, the signal being a current that is proportional to the voltage across the sampling capacitor.
8. 8 . The method of claim 4 , wherein: the current source includes a transistor with a gate; and supplying the signal to the current source involves supplying the signal to the gate of the transistor.
9. 9 . The method of claim 4 , wherein: the signal is generated by a comparator configured to compare the voltage at the first electrode to the reference voltage.
10. 10 . A system comprising: a set of electrodes configured to be coupled to a nerve fiber to implement a neural stimulation procedure; and a stimulation circuit electrically coupled to the set of electrodes, the stimulation circuit being configured to: apply a stimulation current from a current source to the nerve fiber through the set of electrodes during a first stimulation phase of the neural stimulation procedure; and apply a modified stimulation current from the current source to the nerve fiber through the set of electrodes during a second stimulation phase of the neural stimulation procedure, wherein the modified stimulation current is generated based on a voltage difference between (i) a voltage at a first electrode in the set of electrodes, and (ii) a reference voltage derived from voltages at the first electrode and a second electrode in the set of electrodes.
11. 11 . The system of claim 10 , wherein the stimulation circuit is further configured to apply the stimulation current to the nerve fiber through a third electrode during the first stimulation phase of the neural stimulation procedure.
12. 12 . The system of claim 11 , wherein the reference voltage is derived from voltages at the first electrode, the second electrode, and the third electrode.
13. 13 . The system of claim 10 , wherein the stimulation circuit is further configured to adjust one of more characteristics of the stimulation current to generate the modified stimulation current by: generating a signal based on the voltage difference; and supplying the signal to the current source, the current source being configured to receive the signal and adjust one or more characteristics of the stimulation current based on the signal.
14. 14 . The system of claim 13 , wherein: the one or more characteristics include an amplitude, a wave shape, or a duration; and the reference voltage is an average voltage among the set of electrodes.
15. 15 . The system of claim 13 , wherein the first electrode is electrically coupled to the second electrode at a common node to produce the reference voltage at the common node, wherein a sampling capacitor is electrically coupled between the common node and the first electrode, and wherein the stimulation circuit is further configured to: charge the sampling capacitor to a voltage, wherein the voltage represents the voltage difference between the first electrode's voltage and the reference voltage; and generate the signal based on the voltage at the sampling capacitor.
16. 16 . The system of claim 15 , further comprising a voltage-to-current converter that is configured to generate the signal, the signal being a current that is proportional to the voltage across the sampling capacitor.
17. 17 . The system of claim 13 , wherein the current source includes a transistor with a gate, and wherein the stimulation circuit is further configured to supply the signal to the current source by supplying the signal to the gate of the transistor.
18. 18 . The system of claim 13 , further comprising a comparator configured to generate the signal based on a comparison of the voltage at the first electrode to the reference voltage.
19. 19 . A neural stimulation apparatus, comprising: a current source; a set of electrodes coupled to the current source, the set of electrodes being configured to be coupled to a nerve fiber to implement a neural stimulation procedure; and a stimulation circuit electrically coupled to the current source and the set of electrodes, the stimulation circuit being configured to: apply a stimulation current from the current source to the nerve fiber through the set of electrodes during a first stimulation phase of the neural stimulation procedure; generate a reference voltage at a common node, wherein the common node is electrically coupled to a first electrode and a second electrode in the set of electrodes; charge a sampling capacitor to a voltage, wherein the voltage represents a difference between the reference voltage and the first electrode's voltage; and apply a modified stimulation current from the current source to the nerve fiber through the set of electrodes during a second stimulation phase of the neural stimulation procedure, wherein the modified stimulation current is generated based on the voltage at the sampling capacitor.
20. 20 . The neural stimulation apparatus of claim 19 , wherein the stimulation circuit is further configured to adjust one of more characteristics of the stimulation current to generate the modified stimulation current by: generating a signal based on the voltage at the sampling capacitor; and supplying the signal to the current source, the current source being configured to receive the signal and adjust one or more characteristics of the stimulation current based on the signal.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS The present application is a divisional of U.S. patent application Ser. No. 16/566,025 filed Sep. 10, 2019, which claims priority to Provisional Application No. 62/729,479, filed on Sep. 11, 2018, the entirety of which are hereby incorporated by reference herein. TECHNICAL FIELD The present disclosure relates generally to electrical therapeutic systems. More specifically, but not by way of limitation, this disclosure relates differential charge-balancing during high-frequency neural stimulation. BACKGROUND Many chronic diseases, such as epilepsy and depression, can be treated by stimulating the nerves in a patient's body using electrical signals. While such neural stimulation procedures are typically implemented using electrical signals with lower frequencies, e.g., 20 hertz (Hz) to 1 kHz, recent studies show that some diseases may be treatable using electrical signals with higher frequencies, e.g., from 1 kHz to 50 kHz. SUMMARY One example of the present disclosure includes a system comprising a set of electrodes configured to be coupled to a nerve fiber to implement a neural stimulation procedure. The system also comprises a stimulation circuit electrically coupled to the set of electrodes. The stimulation circuit is configured to apply stimulation currents through the set of electrodes to the nerve fiber during a stimulation phase of a treatment cycle in the neural stimulation procedure. The stimulation circuit is also configured to apply recovery currents through the set of electrodes to the nerve fibers during a recovery phase that is subsequent to the stimulation phase in the treatment cycle, the recovery currents having opposite polarities to the respective stimulation currents. The stimulation circuit is also configured to adjust one or more characteristics of the stimulation currents or the recovery currents based on a reference voltage derived from voltages on the set of electrodes, the one or more characteristics of the stimulation currents or the recovery currents being adjusted to reduce a charge buildup on the set of electrodes resulting at least partially from the stimulation phase and the recovery phase. The stimulation circuit is also configured to apply the stimulation currents or the recovery currents with the adjusted one or more characteristics through the set of electrodes to the nerve fiber during a subsequent treatment cycle of the neural stimulation procedure to reduce the charge buildup. Another example of the present disclosure includes a method comprising applying stimulation currents through a set of electrodes to a nerve fiber during a stimulation phase of a treatment cycle in a neural stimulation procedure. The method also comprises applying recovery currents through the set of electrodes to the nerve fibers during a recovery phase that is subsequent to the stimulation phase in the treatment cycle, the recovery currents having opposite polarities to the respective stimulation currents. The method also comprises adjusting one or more characteristics of the stimulation currents or the recovery currents based on a reference voltage derived from voltages on the set of electrodes, the one or more characteristics of the stimulation currents or the recovery currents being adjusted to reduce a charge buildup on the set of electrodes resulting at least partially from the stimulation phase and the recovery phase. The method also comprises applying the stimulation currents or the recovery currents with the adjusted one or more characteristics through the set of electrodes to the nerve fiber during a subsequent treatment cycle of the neural stimulation procedure to reduce the charge buildup. Some or all of these steps can be performed by a neural stimulation device. Still another example of the present disclosure includes a neural stimulation apparatus comprising a first electrode and a second electrode configured to be coupled proximate to a nerve fiber to implement a neural stimulation procedure. The neural stimulation apparatus also comprises a neural stimulation circuit electrically coupled to the first electrode and the second electrode. The neural stimulation circuit is configured to apply stimulation currents to the nerve fiber through the first electrode and the second electrode during a first stimulation phase of the neural stimulation procedure. The neural stimulation circuit is also configured to apply a modified stimulation current to the nerve fiber through the first electrode during a second stimulation phase of the neural stimulation procedure, wherein the modified stimulation current is generated based on a difference between (i) a voltage at the first electrode, and (ii) a reference voltage derived from voltages on the first electrode and the second electrode (e.g., as a result of the first stimulation phase). Yet another example of the present disclosure includes a method comprising applying stimulation currents to a nerve fiber th