Reducing surface area while maintaining implant penetrating profile lowers the brain foreign body response to chronically implanted planar silicon microelectrode arrays.

A consistent feature of the foreign body response (FBR), irrespective of the type of implant, is persistent inflammation at the biotic-abiotic interface signaled by biomarkers of macrophage/microglial activation. Since macrophage-secreted factors shape the foreign body reaction, implant designs that reduce macrophage activation should improve biocompatibility and, with regard to recording devices, should improve reliability and longevity. At present, it is unclear whether the goal of seamless integration is possible or whether electrode developers can modulate specific aspects of the FBR by intentionally manipulating the constitutive properties of the implant.