Fig. 3: Mesh Flexible Electrode SU-8 Plane Guide and Cylindrical Injection Implantation.

a SU-8 Polymer Shuttle-Guided Planar Mesh Electrode Implantation⁴⁰. (i) Shape of the SU-8 polymer shuttle and mesh electrode; (ii) Representative 3D reconstructed confocal fluorescence imaging of mesh electronic device implanted after 6 weeks; The planar mesh electrode after implantation integrates well with the brain tissue, and the size of the detection sites is similar to that of the neurons; b Cylindrical Mesh Electrode Injection Implantation⁴¹. (i) Bright-field microscope image taken in wide-field transmission mode showing partially ejected mesh electronics through a glass needle with an inside diameter of 95 μm, exhibiting significant expansion and unfolding of mesh electronics in aqueous solution. (ii) Time-dependent histology of the mesh electronics/brain tissue interface. Confocal fluorescence microscopy images of 10-μm thick horizontal brain slices sectioned perpendicular to the long axis of mesh probes at 2, 4 and 12 weeks post-injection. Green, red, cyan and blue colors correspond to neuron nuclei (NeuN antibody), neuron axons (neurofilament antibody), astrocytes (glial fibrillary acidic protein, GFAP antibody) and mesh electronics, respectively; c Neuron-Inspired Mesh Electrode²⁴. (i) Overall layout and schematic of the 16-channel electrode with different material layers, and close-up views; The local magnified view of the electrode is shown in the black frame, with an exploded view of the electrode highlighted within the blue dashed box, displaying the different material layers. SU-8, interconnects, and electrodes are represented in red, yellow, and green, respectively; below are the structural characterizations of NeuE, including SEM original images and optical images. Scale bar, 10 μm; (ii) 3D full-probe interface of the mesh electrode, neurons, astrocytes, and microglia 2 weeks post-implantation; From left to right, the images show 2 weeks post-implantation, the 3D interface between the Neuron-Inspired Mesh Electrode (red) and neurons (green), astrocytes (cyan), and microglia (magenta). Scale bar, 200 μm; d Glass Capillary Needle Stitching⁴⁴. (i) A single cylindrical mesh electrode (green) was inserted into different brain regions of mice using a glass capillary needle and simulated in a hydrogel; (ii) 3D mapping of the cylindrical mesh electrode; On the left, a 3D rendering of the probe (red) and the interface with astrocytes (cyan) in the GFAP transgenic mouse brain two weeks after injection. Astrocytes express fluorescent proteins after genetic modification. (White dashed boxes indicate sites I and II); scale bar, 300 μm. On the upper right, high-resolution images of the highlighted regions at sites I and II. Scale bar, 100 μm. On the lower right, 3D mapping showing the interface between the probe (red) and neurons (green) in the YFP-H transgenic mouse brain two weeks after injection. (iii) Two weeks post-injection, the normalized fluorescence intensity of neurons and astrocytes as a function of the distance from probe surface sites I (black) and II (red). Reproduced with permission⁴⁰. Copyright 2023, Siyuan, Z., Xin, T., Weiwen, T., et al., published by Springer Nature. Reproduced with permission⁴¹. Copyright 2018, American Chemical Society. Reproduced with permission²⁴. Copyright 2019, Xiao, Y., Tao Z., Theodore J., Z., et al., published by Springer Nature. Reproduced with permission⁴⁴. Copyright 2023, Jung Min, L., Dingchang, L., Young‐Woo, P., et al., Advanced Science published by Wiley-VCH GmbH.