Fig 1

Soft graphene electrodes. (a) Tilt SEM image of a 64-spot porous graphene array. Scale bar, 1 mm. The inset is the SEM image of an individual electrode active site. Scale bar: 100 μm9. Adapted from Ref.9. (b and c) Laser ablation of liquid crystal graphene oxide (LCGO) electrodes and neural activity of feline visual cortex recorded within 20 s of LCGO electrode implantation 12. Adapted from Ref.12. (d) (left) Photograph and (right) optical microscope images of the electrode array consisting of electrode sites based on Au film, ZnO nanowires and poly(3, 4-ethylenedioxythiophene (PEDOT), and interconnection line based on Au/graphene 38. Scale bars, (left) 10 mm and (right) 450 μm. Adapted from Ref.38. (e) Image of 4 × 4 graphene transistor array 42. Adapted from Ref.42. "

Fig 2

Soft carbon nanotubes (CNTs) electrodes. (a) SEM image of a CNT:poly(sodium 4-styrenesulfonate) (PSS)/poly(vinyl alcohol) (PVA) composite electrode with a width of 10 μm 11. Adapted from Ref.11. (b) Two-channel CNT fiber microelectrodes; inset shows a close view of the active site 49. Scale bar, 200 μm. (c) Results of the methamphetamine rotation test 49. (d) Mean waveforms of single units averaged over multiple 40 sample traces detected by CNT fiber electrodes (the shaded area depicts the mean ± SD) 49. Adapted from Ref.49. "

Fig 3

Chronic neural recording with soft CNT fiber electrodes 33. (a) Four-channel CNT fiber microelectrode array. Scale bar, 5 mm. Inset, SEM image of a CNT fiber electrode tip. Scale bar, 10 μm. (b) Mean waveforms of units detected and isolated from day 1 to day 117 postimplantation with an ~15 μm diameter CNT fiber electrodes. Adapted from Ref.33."

Fig 4

Schematics of the two-layer PDMS microfluidic device assisting insertion of flexible CNTf microelectrodes 56. Adapted from Ref.56. "

Fig 5

Transparent graphene electrodes. (a) Diagram of CLEAR device construction 23. Adapted from Ref.23. (b) Optical evoked potentials recorded by CLEAR device 23. x-scale bars represent 50 ms, y-scale bars represent 100 μV. Adapted from Ref.23. (c) Three different types of transparent graphene multielectrode arrays with different electrode site diameters (100, 150, 200 μm) 58. Adapted from Ref.58. (d) Microscope image of transparent graphene 8-electrode array 14. Adapted from Ref.14. (e) Transparent graphene microelectrode arrays with 16 electrode sites. Each electrode is a 100 μm×100 μm square 26. Scale bar, 500 μm. Adapted from Ref.26. (f) FE-SEM images of the fixed rat cortical neuron cultured on transparent graphene-vertically aligned carbon nanotube hybrid electrodes (TGVH) at 7 days in vitro (DIV) 59. Adapted from Ref.59."

Fig 6

Soft transparent graphene contact lens electrodes (GRACE) 61. (a) Photographs of a GRACE device. Scale bar, 3 mm. Image in the inset demonstrates the high softness of the GRACE. (b) The mfERG responses recorded with a GRACE device. (c) Top, soft and transparent graphene electrode array. Scale bar, 5 mm. Bottom, optical microscopy image showing some of the graphene electrode sites and traces. Scale bar, 150 μm. Adapted from Ref.61. "

Fig 7

Transparent carbon nanotubes electrodes 63. (a) Stretchable transparent CNT electrode array, (b) Light-evoked potentials recorded by the stretchable transparent CNT electrode array under different stimulus intensity and duration. (c) The light-induced artifacts in CNT and Au electrode recording with a recording-site size of 100 μm × 100 μm tested in saline. (d) ECoG recording from a stretchable transparent CNT electrode and two-photon calcium images of the brain region underneath the recording site of the electrode used to record the top traces. Adapted from Ref.63. "

Fig 8

MRI compatible neural electrodes made from carbon nanomaterials. (a) GF bipolar microelectrode assembly 32. Scale bar, 1 cm; inset, 100 μm. Adapted from Ref.32. (b) Representative three serial coronal scans from rostral (left) to caudal (right) of EPI images from rat brains implanted with a GF (top) and PtIr (bottom) bipolar microelectrode, with the middle images depicting the electrode implant sites 32. Adapted from Ref.32. (c) Horizontal sections of the T2-weighted images of a rat implanted contralaterally with a Parylene-C-insulated CNT fiber (red) and PtIr microwire (blue) 33. Scale bar, 1.5 mm (inset). Adapted from Ref.33. "