Microfabricated porous silicon backbone for stable neural interfaces

• A novel neural electrode was proposed to establish stable neural interfaces.
• A critical microfabrication process was developed for PSi backbone.
• The microfabricated PSi backbone had better biocompatibility than Si.

To fabricate a porous silicon–polymer hybrid neural electrode with the capability of adaptive stiffness, a critical microfabrication process was developed and the porous silicon (PSi) backbone of the neural electrode was prepared for mass production on 8-in. wafers via microelectromechanical systems (MEMS) technologies. Surface characteristics of the microfabricated PSi backbone were determined using scanning electronmicroscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared spectrum (FTIR). Moreover, acute cytotoxicity of the PSi backbone was assessed by seeding a mouse fibroblast cell line (L929) on the surface. After 2 days of culture, morphology of cells was observed using a fluorescence microscope, and relative cell viability was also used to quantitatively evaluate the cytotoxicity. Compared to Si samples, relative cell attachment of PSi samples was 192.77±27.19% due to the nano featured surface providing more suitable sites for cell adhesion, indicating that the microfabricated PSi backbone was cytocompatible.