An active electronic, high-density epidural paddle array for chronic spinal cord neuromodulation.

Area of Science:

• Biomedical Engineering
• Neuroscience
• Medical Devices

Background:

• Epidural electrical stimulation (EES) is a valuable tool for nervous system research and therapy.
• Current EES devices are limited by the number of wires, restricting electrode density and treatment area.
• A need exists for advanced EES systems with integrated electronics to overcome these limitations.

Purpose of the Study:

• To develop and evaluate a novel smart EES paddle with a high-density programmable electrode array and on-paddle electronics.
• To assess the biocompatibility and chronic in vivo performance of the developed EES device.
• To explore the utility of spatial electrode encoding and machine learning for EES parameter inference.

Main Methods:

• Development of a 60-electrode EES paddle with an embedded active electronic multiplexer and hermetic packaging.
• Extensive reliability testing, including ISO 10993-1 biocompatibility and hermetic seal leak rate determination.
• Chronic in vivo evaluation of the EES device implanted on the ovine lumbosacral spinal cord for 15 months.

Main Results:

• The smart EES paddle demonstrated nominal performance and no device-related malfunctions during the 15-month chronic implantation in sheep.
• The onboard multiplexer allowed flexible electrode configuration for tailored stimulation.
• Stereotyped motor responses and local field potentials were observed, and machine learning models accurately inferred EES parameters using spatial encoding.

Conclusions:

• The developed high-density EES paddle with active electronics is suitable for chronic implantation and advanced neural interfacing.
• This technology facilitates integration of computation and processing directly into neural interface devices.
• It opens new possibilities for studying nervous system function and developing therapies for neural injury and dysfunction.