Graphene-integrated Microfluidic Platforms for Electrical Probing in Retina

Graphene is of growing interest in biological and biomedical fields due to its extraordinary physical properties and excellent biocompatibility. Combining graphene field-effect transistors and scanning photocurrent microscopy with microfluidic platforms, we designed a new approach to investigate electrical signals in the mouse retina. At the optic nerve head (ONH) of the retina, significant photocurrent signals were detected, indicating the electrical activity from this region can modulate the carrier concentration of the graphene and induce local potential gradients. The built-in electrical field can efficiently separate photo-excited electron-hole pairs, leading to intense photocurrent responses in the graphene underneath the ONH. We also show that no apparent photocurrent signal was observed in the graphene underneath either dehydrated or fixed retinal tissues, verifying that the photocurrent responses generated in the graphene underneath the ONH were indeed induced by the electrical activity in living retina.