Neuromodulation IC With Blocking Circuit for Artifact-Free Recording
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Solution Overview
Problem
Existing neuromodulation systems face challenges in achieving true closed-loop operation due to stimulation artifacts that saturate amplifiers and corrupt neural signal recordings.
Innovation Solution
The system employs co-designed recording and stimulation subsystems with a blocking circuit to isolate recording circuits during stimulation, ensuring minimal interference through good charge balance, common voltage references, large linear input voltage ranges, and fast recovery mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical stimulation is delivered to treat neurological conditions, then therapeutic effect is achieved, but stimulation artifacts saturate amplifiers and corrupt neural signal recordings
Solution Approach 1:
The system segments the recording and stimulation functions into separate operational phases. A blocking circuit isolates the recording amplifier from stimulation artifacts by switching the recording input to ground during stimulation delivery, enabling both functions to coexist in the same device without mutual interference
Solution Approach 2:
The system performs preliminary actions by pre-synchronizing the blocking circuit with the stimulation waveform. The blocking circuit is activated just before stimulation begins and deactivated immediately after, preventing artifact saturation before it occurs and enabling rapid recovery of recording capability
2Measurement precision
If separate devices are used for stimulation and recording, then artifact interference is avoided, but closed-loop feedback capability is lost
Solution Approach 1:
The system merges stimulation and recording functions into a single integrated device. By combining the stimulator, recorder, and blocking circuit into one system, true closed-loop operation becomes possible where neural signals can be recorded and stimulation can be delivered in real-time within the same device platform
Solution Approach 2:
The blocking circuit acts as an intermediary element between the stimulator and recorder. It mediates the interaction between stimulation and recording by selectively isolating the recording amplifier during stimulation phases, enabling both functions to operate within the same integrated device without mutual interference
3Productivity
If recording continues during stimulation, then continuous monitoring is maintained, but amplifier saturation and artifact corruption occur
Solution Approach 1:
The system implements periodic action by rhythmically switching the blocking circuit in synchronization with the stimulation waveform. The blocking circuit alternates between active (blocking) and inactive (recording) states, allowing continuous monitoring capability while preventing artifact saturation during stimulation phases
Solution Approach 2:
The system converts the harmful effect of stimulation artifacts into a beneficial operational mode. By deliberately blocking the recording input during stimulation, the system transforms what would be corrupting artifacts into a controlled switching opportunity, enabling artifact-free recording capability while maintaining continuous monitoring readiness
Data Source
AI summary
Representative methods, apparatus and systems are disclosed for providing concurrent electrical stimulation and electrical recording in a human or non-human subject, such as for neuromodulation, with the apparatus coupleable to an electrode array. A representative apparatus is typically an integrated circuit including: stimulation circuits, recording circuits, and blocking circuits responsive to control signals to block the stimulation voltage or current on an electrode from a corresponding recording circuit, while other recording circuits may simultaneously record electrical signals from other electrodes and generate recorded data. A representative stimulation circuit may include current sources; a first multiplexer for current source selection; a second multiplexer for electrode selection; a switchable voltage offset circuit; a switchable grounding circuit; and a stimulation controller providing control signals to provide the electrical stimulation, such as biphasic or monophasic stimulation, and bipolar or unipolar stimulation. Off-chip communication, control, along with power and voltage level control, are also provided.