Brain Machine Interface Sample Projects

This study developed a custom skull cap with precision guide holes to stabilize the brain and dura, provide sufficient support to microwire along the insertion path, and minimize the unsupported length of microwire during dura penetration and deeper insertion. A cap matched to individual skull anatomy with offset for brain stabilization was designed based on computed tomography (CT) scan of the rat head and fabricated by stereolithography. Micro-milling and wax molding were conducted to fabrication precision insertion guide inside the cap. Through a test cube with precision guide, a 25 µm diameter tungsten microwire penetrated through the dura mater and was manually inserted over 10 mm into the brain without buckling. In comparison, without the precision guide, insertion of the same microwire caused over 2 mm dimpling of the dura without penetration and finally led to wire buckling.

A cantilever beam-based flexible high-resolution system for evaluation of microelectrode force and membrane dimpling depth was developed. The easily duplicable and reconfigurable system was shown feasible for in vivo evaluation of both the pia-only and dura-pia penetration process with either microwires or silicon-based probe shanks. For the first time, we revealed the linear relationship between microwire diameter and membrane rupture force/dimpling depth for in vivo rat brain insertion and for dura penetration.

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