Novel multi-sided, microelectrode arrays for implantable neural applications.

Area of Science:

• Biomedical Engineering
• Materials Science
• Neuroscience

Background:

• Neural recording and drug delivery require advanced microfabrication techniques.
• Parylene-based materials offer biocompatibility and flexibility for neural interfaces.

Purpose of the Study:

• To present a new parylene-based microfabrication process for neural recording and drug delivery.
• To explore a large design space for electrode placement and structural flexibility.
• To investigate the performance of novel edge electrodes.

Main Methods:

• A six-mask process utilizing chemical mechanical polishing for versatile electrode site creation (top-side, back-side, edge).
• Electroplating to increase surface area on exposed edge electrodes.
• Modification of edge electrodes with Poly(3,4-ethylenedioxythiophene) (PEDOT).
• Finite element modeling to compare planar and edge electrode performance.

Main Results:

• Achieved electrode sites on three exposed sides of the device.
• PEDOT-modified edge electrodes (85 µm²) exhibited an impedance of 200 kΩ at 1 kHz.
• Successfully recorded single-unit neural activity in acute animal studies using edge electrodes.
• Finite element models indicated edge electrodes enhance the volume of tissue sampled.

Conclusions:

• The developed parylene microfabrication process offers significant design flexibility for neural applications.
• Edge electrodes, particularly when modified with PEDOT, demonstrate promising performance for neural recording.
• This technology has the potential to improve neural recording by increasing the sampled tissue volume.