Fig. 5
Multi-electrode ERG recording with soft, transparent graphene electrode array. a Diagram of graphene multi-electrode array construction showing the layered structures. b Top, a soft, transparent graphene electrode array positioned over a printed paper to show its optical transparency. Scale bar, 5 mm. The recording sites, arranged in a linear pattern, are located in the region marked by the red box. Under each recording site, there is a channel number patterned with Au which is optically opaque. Bottom, optical microscopy image showing some of the graphene electrode sites and traces. The red box marks the graphene recording sites. The black arrow points to the patterned SU-8 insulation layer on one electrode. Scale bar, 150 μm. c A stripped graphene electrode array positioned over a dilated rabbit eye. Scale bar, 5 mm. d A schematic drawing showing the positions of the recording channels (marked by the squares) on a rabbit eye. Channel 1 to 13 was evenly distributed over equator of the cornea from temporal to nasal periphery. e A representative set of the multi-electrode scotopic ERG response waveforms. Stimulus strength, 0.3 cd s m−2. The placement of the graphene electrode array is shown in d. The crosses mark the positions of the a and b- waves. Channels 4 and 7 have abnormally high impedance and are considered non-functional. f Plots of the electrode impedance values |Z| at 100 Hz, a- and b-wave amplitudes of the ERG signals recorded from different channels associated with e. The lines show the quadratic curve fitting of the a- and b-wave amplitudes. g Spatial profile of b-wave amplitudes under different stimulation strength. 0 dB corresponds to 3.0 cd s m−2. The dots in the overlaid grid mark the positions with actual experimental data
