Benchtop and bedside validation of a low-cost programmable cortical stimulator in a testbed for bi-directional...

Area of Science:

• Neuroscience
• Biomedical Engineering
• Rehabilitation Technology

Background:

• Restoring movement and sensation requires bi-directional brain-computer interfaces (BD-BCI) that can simultaneously record motor commands and provide sensory feedback.
• Existing systems often face challenges in cost, complexity, and real-world applicability for research.

Purpose of the Study:

• To develop and validate a low-cost, wireless, and battery-powered testbed for exploring BD-BCI concepts.
• To integrate a custom programmable direct cortical stimulator (DCS) into an embedded BCI system.
• To ensure the safety and efficacy of the BD-BCI system through phantom and human testing.

Main Methods:

• A custom programmable DCS was integrated into an embedded BCI system.
• Stimulator output was validated against an FDA-approved device in phantom brain tissue and in an epilepsy patient.
• Safety features including impedance monitoring and artifact mitigation were implemented and tested.
• Concurrent operation of interleaved stimulation and BCI decoding was tested.

Main Results:

• The custom stimulator demonstrated output equivalency to an FDA-approved device (R² > 0.99).
• Advanced safety features achieved significant artifact reduction (64.5%) and accurate impedance monitoring (R² > 0.99).
• Online BCI decoding accuracy reached 93.2% during interleaved stimulation.
• Brain stimulation mapping in an epilepsy patient confirmed equivalent responses between the custom and FDA-approved stimulators.

Conclusions:

• This study successfully validated a fully-programmable electrical stimulator integrated into an embedded BCI system.
• The developed low-cost BD-BCI system is safe, wireless, and serves as a valuable research testbed.
• This work represents a critical milestone toward the development of fully-implantable BD-BCI systems.