Extended Data Fig. 3: Time-dependent histology studies of brain tissue reaction.

a, Representative photograph of mesh electronics with high-density electrode arrays. b-f, 3D reconstructed confocal fluorescence images showing mesh electronics sustaining open mesh structures across multiple brain regions, which interpenetrate with neural networks and introduce minimal immune response at 6-week post-implantation. b, High-density mesh electronics implanted in the cortex. Inset: zoomed-in views of the regions highlighted by the yellow box. Green, purple, blue and red label neurons, astrocytes, nuclei and mesh electronics, respectively. c, 16-channel mesh electronics implanted in both cortex and hippocampus with a designed 30-degree angle corresponding to the dorsal-ventral direction. d, Zoomed-in view of the hippocampal region highlighted by the cyan box in (c). e-f, Neuron interpenetrating with electrodes and interconnects with subcellular feature size. Individual electrodes are highlighted by yellow dashed circles in (d) and (e), tissue slice was labeled for neurons (green), nuclei (blue) and mesh electronics (red). g-h, Representative immunofluorescence images of brain tissues at 2-week, 6-week, 12-week, and 1-year post-implantation with mesh (g) and thin-film (h) electronics for characterizing immune response. Mesh and thin-film electronics are implanted in the contralateral hemispheres of the same animals. Tissue slices were labeled for astrocytes (red), microglia (purple), neurons (green), and nuclei (blue). Time-dependent histology studies have been repeated on n = 5 independent samples for each time point, with statistical analyses shown in Fig. 2f-i.