Methods and systems for providing closed loop control of stimulation provided by an implantable stimulator device are disclosed herein. The disclosed methods and systems use a neural feature prediction model to predict a neural feature, which is used as a feedback control variable for adjusting stimulation. The predicted neural feature is determined based on one or more signals from an accelerometer configured in contact with the patient. The disclosed methods and systems can be used to provide closed loop feedback in situations, such as sub-perception therapy, when neural features cannot be readily directly measured.

Methods and systems for providing closed loop control of stimulation provided by an implantable stimulator device are disclosed herein. The disclosed methods and systems use a neural feature prediction model to predict a neural feature, which is used as a feedback control variable for adjusting stimulation. The predicted neural feature is determined based on one or more signals from an accelerometer configured in contact with the patient. The disclosed methods and systems can be used to provide closed loop feedback in situations, such as sub-perception therapy, when neural features cannot be readily directly measured.

Measuring a neural response to a stimulus comprises applying an electrical stimulus, then imposing a delay during which the stimulus electrodes are open circuited. During the delay, a neural response signal present at sense electrodes is measured with a measurement amplifier, while ensuring that an impedance between the sense electrodes is sufficiently large that a voltage arising on the sense electrode tissue interface in response to the stimulus is constrained to a level which permits assessment of the neural response voltage seen at the sense electrode. For example the input impedance to the measurement amplifier (ZIN) can be, where ZC is the sense electrode(s) constant phase element impedance, Vs1Vs2 is the differential voltage arising on the sense electrode tissue interface, and VE is the neural response voltage seen at the sense electrode.

Measuring a neural response to a stimulus comprises applying an electrical stimulus, then imposing a delay during which the stimulus electrodes are open circuited. During the delay, a neural response signal present at sense electrodes is measured with a measurement amplifier, while ensuring that an impedance between the sense electrodes is sufficiently large that a voltage arising on the sense electrode tissue interface in response to the stimulus is constrained to a level which permits assessment of the neural response voltage seen at the sense electrode. For example the input impedance to the measurement amplifier (ZIN) can be, where ZC is the sense electrode(s) constant phase element impedance, Vs1Vs2 is the differential voltage arising on the sense electrode tissue interface, and VE is the neural response voltage seen at the sense electrode.

An implantable medical device (IMD) includes multiple stimulation engines (SEs) for independently stimulating respective electrode sets of a lead system. A voltage multiplier (VM) is configured to generate an adjustable target voltage at an output node. Each stimulation engine includes first switching circuitry to switchably connect an anodic node of the SE to the VM output node and second switching circuitry to switchably connect a cathodic node of the SE to a current sink circuit. Discharge switching circuitry may be disposed between the anodic and cathodic nodes of each SE. A selector and associated digital control logic block are operative to generate control signals for independently controlling respective SEs such that each SE may be activated to stimulate or discharge a corresponding select set of electrodes independently from or in concert with remaining SEs.

Disclosed herein are a neural signal feedback system and method. The neural signal feedback system includes: a microelectrode array unit configured such that a plurality of microelectrodes is disposed on a substrate and such that one microelectrode, which is a reference electrode, and corresponding electrode groups including other microelectrodes located at different same distances from the reference electrode are set; and an analysis and determination unit configured to compare neural signal values, measured in the microelectrode array unit, with a preset reference value, and to determine whether to apply the electrical stimulation of the microelectrode array unit. The analysis and determination unit performs re-measurement after the application of electrical stimulation, and repeats the application of electrical stimulation and measurement until the measured values reach the reference value.

Disclosed herein are a neural signal feedback system and method. The neural signal feedback system includes: a microelectrode array unit configured such that a plurality of microelectrodes is disposed on a substrate and such that one microelectrode, which is a reference electrode, and corresponding electrode groups including other microelectrodes located at different same distances from the reference electrode are set; and an analysis and determination unit configured to compare neural signal values, measured in the microelectrode array unit, with a preset reference value, and to determine whether to apply the electrical stimulation of the microelectrode array unit. The analysis and determination unit performs re-measurement after the application of electrical stimulation, and repeats the application of electrical stimulation and measurement until the measured values reach the reference value.

Disclosed is an implantable device for measuring an evoked neural response. The implantable device comprises a stimulus source configured to deliver neural stimuli via one or more stimulus electrodes to neural tissue, the neural stimuli being configured to evoke a neural response from the neural tissue. The implantable device further comprises a measurement amplifier configured to amplify a signal sensed between a first input of the measurement amplifier by a first measurement electrode and a second input of the measurement amplifier by a second measurement electrode subsequent to a provided neural stimulus, the sensed signal comprising the evoked neural response. The implantable device further comprises a control unit configured to: control the stimulus source to deliver a neural stimulus; and measure the evoked neural response of the amplified sensed signal. The implantable device further comprises one or more impedance elements configured to provide a negative impedance to at least one of the first and second inputs of the measurement amplifier.

Disclosed is an implantable device for measuring an evoked neural response. The implantable device comprises a stimulus source configured to deliver neural stimuli via one or more stimulus electrodes to neural tissue, the neural stimuli being configured to evoke a neural response from the neural tissue. The implantable device further comprises a measurement amplifier configured to amplify a signal sensed between a first input of the measurement amplifier by a first measurement electrode and a second input of the measurement amplifier by a second measurement electrode subsequent to a provided neural stimulus, the sensed signal comprising the evoked neural response. The implantable device further comprises a control unit configured to: control the stimulus source to deliver a neural stimulus; and measure the evoked neural response of the amplified sensed signal. The implantable device further comprises one or more impedance elements configured to provide a negative impedance to at least one of the first and second inputs of the measurement amplifier.

An interventional device (110) for detecting nerve activity, is provided. The interventional device includes: a magnetic sensor (120) that is coupled to an insertable portion of the interventional device. The magnetic sensor (120) is configured to generate signals in response to magnetic fields produced by nerve activity. A system (200) is also provided. The system includes the interventional device (110) and a controller (140) that is configured to receive the signals generated by the magnetic sensor (120), and to output a detection result indicative of nerve activity in response to the received signals.