RT Journal Article
SR Electronic
T1 Ultra-sensitive measurement of brain penetration mechanics and blood vessel rupture with microscale probes
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2020.09.21.306498
DO 10.1101/2020.09.21.306498
A1 Abdulmalik Obaid
A1 Yu-Wei Wu
A1 Mina Hanna
A1 Omar Jáidar
A1 William Nix
A1 Jun Ding
A1 Nicholas Melosh
YR 2020
UL http://biorxiv.org/content/early/2020/09/22/2020.09.21.306498.abstract
AB Microscale electrodes, on the order of 10-100 μm, are rapidly becoming critical tools for neuroscience and brain-machine interfaces (BMIs) for their high channel counts and spatial resolution, yet the mechanical details of how probes at this scale insert into brain tissue are largely unknown. Here, we performed quantitative measurements of the force and compression mechanics together with real-time microscopy for in vivo insertion of a systematic series of microelectrode probes as a function of diameter (7.5–100 μm and rectangular Neuropixels) and tip geometry (flat, angled, and electrochemically sharpened). Results elucidated the role of tip geometry, surface forces, and mechanical scaling with diameter. Surprisingly, the insertion force post-pia penetration was constant with distance and did not depend on tip shape. Real-time microscopy revealed that at small enough lengthscales (<25 μm), blood vessel rupture and bleeding during implantation could be entirely avoided. This appears to occur via vessel displacement, avoiding capture on the probe surface which led to elongation and tearing for larger probes. We propose a new, three-zone model to account for the probe size dependence of bleeding, and provide mechanistic guidance for probe design.Competing Interest StatementThe authors have declared no competing interest.