Neurostimulation Interface Circuit Isolation for Recording Protection

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Solution Overview

Problem

The large voltage difference between neurostimulation and recording circuits in existing systems poses challenges in protecting the recording circuitry from damage during stimulation, as high voltage stimulation signals can interfere with low voltage recording signals, leading to overvoltage conditions and potential tissue damage.

Innovation Solution

An interface is introduced between the stimulation and recording elements, isolating the recording circuit from the stimulation circuit during active stimulation and overvoltage conditions, providing a low impedance and low noise path when not stimulating, and high impedance when stimulating to prevent current and voltage from entering the recording circuit, thus optimizing signal reception and protecting the recording circuitry.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If neurostimulation and recording circuits share common electrodes and circuitry, then device complexity is reduced, but the recording circuitry becomes vulnerable to damage from high-voltage stimulation signals

Engineering Contradiction:

Improvecircuit integrationVSAvoidrecording circuit protection

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent segments the circuit into distinct stimulation and recording pathways with separate signal processing chains. The stimulation circuit generates high-voltage pulses through dedicated output stages, while the recording circuit uses separate amplification and filtering paths, preventing high-voltage signals from contaminating the low-voltage recording channels.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces isolation components and impedance-matching interfaces between stimulation and recording circuits. These intermediary elements act as buffers that allow the circuits to share common electrodes while preventing direct electrical coupling that would expose the recording circuitry to damaging high-voltage stimulation signals.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Power

If high-voltage stimulation signals are applied through shared electrodes, then stimulation effectiveness is improved, but low-voltage recording signals become corrupted by overvoltage conditions

Engineering Contradiction:

Improvestimulation voltageVSAvoidrecording signal accuracy

Core Design Contradiction:

PowerVSMeasurement precision

Solution Approach 1:

The patent applies different electrical characteristics to different parts of the circuit. The stimulation pathway is designed with high-voltage tolerance and current-sourcing capability, while the recording pathway maintains high input impedance and low-noise characteristics. This local differentiation allows each circuit to optimize its performance without compromising the other.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements preliminary signal conditioning and filtering stages in the recording pathway that prepare the low-voltage signals before they can be affected by stimulation artifacts. The circuit proactively establishes proper biasing and impedance matching before stimulation occurs, preventing signal corruption rather than attempting to correct it afterward.

Inventive Principle:

Principle #10Preliminary action

3Productivity

If the recording circuit operates continuously to capture neural signals, then data acquisition is improved, but the circuit remains exposed to damage during stimulation events

Engineering Contradiction:

Improvesignal recording capabilityVSAvoidovervoltage damage risk

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent incorporates protective elements such as clamping diodes, transient voltage suppressors, and isolation barriers that are pre-configured in the recording circuit pathway. These cushioning elements remain inactive during normal operation but automatically activate during stimulation events to clamp voltage excursions and protect the sensitive recording components from overvoltage damage.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentUS11833353B2Electrical isolation of neurostimulation circuitry from neurorecording circuitry

Publication Date: 2023.12.05 VERITAS IP LLC

AI summary

Various embodiments of an interface control subsystem may be used between an electrode terminal and a recording terminal of a neurostimulation and neurorecording system. The interface control subsystem may operate in three modes. In a disable mode, a first transistor and a second transistor disposed between the electrode terminal and the recording terminal may operate in a cutoff region and generate a high impedance. In an active mode, the first transistor and the second transistor may operate in a saturation region and generate a low impedance. In a stimulation mode, the first transistor and the second transistor operate in a triode region and generate an impedance between the high impedance of the disable mode and the low impedance of the active mode. The interface control subsystem may further limit voltage at the recording terminal in response to a detected overvoltage condition.