Fig. 2 | Nature Communications

Fig. 2

From: Deep 2-photon imaging and artifact-free optogenetics through transparent graphene microelectrode arrays

Fig. 2

Structural 2-photon imaging through a graphene microelectrode array. a After placement of head-post (not shown), craniotomy, and dura removal, the graphene microelectrode array is placed on the surface of the primary somatosensory cortex (SI). The exposure is covered with agarose and closed with a coverslip. Dental acrylic is used to fix the coverslip and the arrays’ connecting wires to reduce motion. b Bright-field image of an exposure with graphene microelectrode array. Graphene electrodes and wires in the center of the array are not visible, but the gold wires for connection to the amplifier board. Scale bar, 500 µm. c Detection of EGFP-expressing interneurons in GAD67-GFP mice below a single graphene electrode (yellow outline). Images were acquired using 2-photon excitation at 905 nm (laser power from 3 mW at the surface to 57 mW at 600 µm cortical depth). d The same region as in c is shown, but after intravascular injection of FITC-dextran (2 MDa); images were acquired using 2-photon excitation at 950 nm (laser power from 8 mW at the surface to 77 mW at 600 µm cortical depth). e The same region as in c, d is shown, but after additional intravascular injection of Alexa Fluor 680-dextran (2 MDa); images were acquired using 2-photon excitation at 1280 nm (laser power from 2 mW at the surface to 44 mW at 1200 µm cortical depth). ce Show maximum intensity projections (MIPs) of images acquired at different depths (step size: 3 µm) below the cortical surface (MIP range is indicated above individual images). Scale bar for ce, 100  µm. f Orthogonal (XZ) MIP of the Alexa Fluor 680-dextran dataset shown in e; graphene microelectrode array (A) and cortical surface (S) are on the top of the image. Scale bar, 100 µm

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