A flexible 3-dimensional microelectrode array for in vitro brain models.

Area of Science:

• Neuroscience
• Biomedical Engineering
• Materials Science

Background:

• Traditional 2D models limit studying cell-environment interactions in 3D tissues.
• Existing electrophysiological methods struggle to record from multiple locations in 3D neural networks simultaneously.

Purpose of the Study:

• To develop a 3D flexible microelectrode array (3DMEA) for non-invasive, high-channel-count electrophysiological recordings in 3D neural cultures.
• To enable simultaneous measurement of neuronal activity throughout a 3D neural network in vitro.

Main Methods:

• Fabrication of thin-film, 3D flexible microelectrode arrays using polyimide probe arrays on glass substrates.
• Mechanical actuation to position probes vertically, relying on plastic deformation for alignment.
• Seeding human induced pluripotent stem cell (hiPSC)-derived neurons and astrocytes in a collagen hydrogel onto the 3DMEA.

Main Results:

• The 3DMEA successfully supported the growth and maturation of neural networks in a 3D hydrogel environment.
• Action potential spike and burst activity were recorded from functional neurons in 3D for over 45 days in vitro.
• The platform demonstrated 256 channels for recording or stimulation, integrating with standard electrophysiology hardware.

Conclusions:

• The developed 3DMEA provides a straightforward and effective platform for non-invasive electrophysiological characterization of 3D neural networks.
• This technology advances the study of complex neural circuits and cell-environment interactions in a more physiologically relevant 3D context.
• The 3DMEA facilitates long-term monitoring of functional neuronal activity in 3D cultures, crucial for understanding neurological diseases and testing therapeutics.