The 128-channel fully differential digital integrated neural recording and stimulation interface

Area of Science:

• Neuroscience
• Biomedical Engineering
• Integrated Circuit Design

Background:

• Accurate monitoring and stimulation of neural activity are crucial for understanding brain function and developing neurological therapies.
• Existing neural interfaces often face limitations in channel count, power consumption, and noise performance.

Purpose of the Study:

• To develop and validate a fully differential, high-channel-count integrated neural interface.
• To achieve low-power, low-noise performance for both neural recording and stimulation.

Main Methods:

• Designed and implemented a 128-channel integrated neural interface with 8x16 arrays of recording and stimulation circuits.
• Utilized a two-stage amplification and conditioning circuit with a column-parallel successive approximation (SAR) analog-to-digital converter (ADC) for recording channels.
• Incorporated voltage-mode stimulation capabilities for both monophasic and biphasic stimulation.

Main Results:

• Achieved a low power consumption of 15.5 µW per recording channel, including the SAR ADC.
• Measured an input-referred noise of 6.08 µVrms over a 5-kHz bandwidth, yielding a noise efficiency factor of 5.6.
• Demonstrated a maximum stimulation current of 5 mA with a quiescent power dissipation of 51.5 µW per stimulation channel.

Conclusions:

• The developed 128-channel neural interface offers a high-performance, low-power solution for neural recording and stimulation.
• The integrated design, implemented in 0.35-µm CMOS technology, shows significant potential for advancing neuroscience research and therapeutic applications.
• Successfully validated the interface in an in vitro epileptic seizure model, demonstrating its efficacy in complex neural recording scenarios.