Laser-Microfabricated Polymer Multielectrodes for Intraspinal Microstimulation.

Area of Science:

• Biomedical Engineering
• Neuroscience
• Materials Science

Background:

• Intraspinal microstimulation (ISMS) is crucial for neurological research and potential therapies.
• Traditional microwire electrodes face limitations in flexibility and charge handling.
• Advancements in polymer-based materials offer new possibilities for neural interface design.

Purpose of the Study:

• To design, fabricate, and characterize novel polymer-based multielectrodes for ISMS.
• To compare the performance of these new electrodes against traditional microwire electrodes.
• To evaluate the in vivo functionality and biocompatibility of the polymer-based multielectrodes.

Main Methods:

• Fabrication of three-channel multielectrodes using poly(dimethylsiloxane) (PDMS) and platinum-iridium (Pt-Ir) via laser microfabrication.
• Mechanical and electrochemical characterization in bench environments.
• In vivo assessment in a domestic pig model, including electrochemical and functional evaluations.

Main Results:

• Polymer-based multielectrodes exhibited significantly greater flexibility and charge storage capacity than microwire electrodes.
• In vivo studies showed higher charge injection limits and the ability to elicit functional motor responses (knee extension torques).
• Histological analysis indicated greater acute tissue damage with polymer-based electrodes when using needle insertion aids.

Conclusions:

• PDMS-based multielectrodes offer improved flexibility and charge injection over traditional microwire electrodes.
• Functional responses were achieved in vivo, demonstrating the potential of these devices for ISMS.
• Further investigation into alternative insertion methods is recommended to mitigate tissue damage and enhance biocompatibility.