Multi-layer brain-mimicking phantom for replicating dura and pia membrane dimpling and rupture properties during...

Development of novel neural interfaces faces buckling challenges and heavily relies on trial-and-error tests via in vivo animal brain insertions for design optimizations toward the minimal-damaging version for enhanced recording and stimulation outcome.

To enable low-cost and fast-turnaround neural interface development and to enable previously impossible insertions via new understanding of the cutting process, this study developed a reproducible, multi-layer brain-mimicking phantom designed to replicate the rodent pia and dura mater dimpling and rupture force performance observed during in vivo tests. The phantom was composed of a 0.5% (w/v) agarose cortex layer, a 1.01% (w/v) agarose pia mater layer, and a pre-stretched polyvinyl chloride (PVC) dura mater layer, assembled via easily duplicable benchtop protocols. Using a cantilever-beam force measurement system, rupture force and dimpling depth were quantified across microwires of varying diameters (12-100 μm), materials (tungsten, stainless steel), and tip geometries, as well as segmented silicon probe shanks.

The developed multi-layer phantom test results fell within the in vivo Sprague-Dawley rat data range. At the same time, phantom insertion trial variability was substantially lower than in vivo tests.

The developed multi-layer phantom enabled a repeatable, low-cost, early-stage screening platform of novel electrode designs. The phantom's modular design also allowed tuning of layer thickness and stiffness of each layer for different species or devices, offering a customizable testing platform to accelerate novel neural implant development and reduce animal use.