NANO.IL.

Towards Improved Chronic Brain-Machine Interfacing Technologies: Design, Fabrication, Electrophysiology and Bio-integration of Polyimide Based MEA Platform with Rat Cortical Neurons

Shun-Ho Huang Nanoscience-Neuroscience, The Harvey M. Kruger Family Center for Nanoscience, Dept of Neuroscience, The Hebrew University of Jerusalem, Jerusalem, Jeruslaem, Israel

Implantable Multi-Electrode-Array (MEA) platforms into brain tissue serve as important tool for basic neuroscientific research and in clinical applications such as in brain-machine interfaces (retinal implants, brain and peripheral implants). Current technologies fail to support long-term quality recordings of extracellular field potentials (FPs) by implanted MEA platforms. This is mainly due to numerous device/living-tissue incompatibilities. To extend the recording time and the recording qualities we designed and constructed scalable polyimide (PI) based-platforms (280 µm wide and 16 µm thick). The platform is subdivided into a distal perforated part and a solid proximal part. The perforated part (opening area = 45-65 µm by 8 µm) of the PI platform tapers to form a sharp tip. The PI platforms were composed of 2 or 16 planar microelectrodes (Ø = 25 µm) located along the edges of the platforms tip. Electrodes were implanted into rat primary somatosensory cortex (S1) or to frontal associative area (FrA). Immunohistological cryosections of the PI platform together with the surrounding tissue revealed that microglia, astrocytes and neurites extended into the perforated platform, leading to apparent local “anchoring” of the brain tissue to the platform. To test the durability and recording quality of the system we conducted weekly telemetric recordings from freely moving rats. The longest recording that we have obtained so far lasted 8 months (the experiments are still on going). Recordings of the electrophysiological signals for weeks revealed large extracellular action potentials. The immunohistological cryosections of the PI platform together with the surrounding tissue revealed minimal foreign body response. These observations are consistent with the view that the use of perforated PI platform functionalized by polyethyleneimine and laminin facilitates mechanical integration of the platform with cortical tissue and thereby supports long-term stable recordings from freely moving rats.

Supported by the NIH Award Number U01NS099687









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