Electrocorticography (ECoG) is a valuable tool used to investigate brain activity with a better spatial resolution compared to the EEG system. We describe the fabrication of new polyimide electrodes for EcoG recording, used to research the development of wake-sleep cycles in chicken embryos. The microelectrodes are connected to a dedicated system for data acquisition. Current ECoG recordings in birds are usually made with metallic wire electrodes placed on the dura surface though a hole on the skull. This approach is not reliable for long term acquisitions (a few days) as the electrodes may generate signal artefacts and cause bleeding. Recently, flexible polymer electrodes have been proposed to avoid the stiffness of the metal wire and to improve compliance with brain surface. The electrodes are fabricated on a 75µm thick polyimide film substrate. Gold lines are used as conductive wires to read the brain potentials and transfer them to the acquisition system. To protect and isolate gold tracks, a protective spinnable polyimide layer (Hitachi PI2610) is subsequently deposited. Then, an aluminium hard mask is deposited and patterned by a lithographic step, to protect and to open a window by oxygen plasma etch in the protective layers, so that the gold pads are exposed. Finally, the electrodes are ready and are detached from the carrier tape. Preliminary insertion tests have showed the feasibility of flexible electrodes insertion in the chicken brain.

Flexible polyimide electrodes for ECoG in chicken embryos

PAONESSA, SIRIANA;PIERI, FRANCESCO;DI PASCOLI, STEFANO
2017-01-01

Abstract

Electrocorticography (ECoG) is a valuable tool used to investigate brain activity with a better spatial resolution compared to the EEG system. We describe the fabrication of new polyimide electrodes for EcoG recording, used to research the development of wake-sleep cycles in chicken embryos. The microelectrodes are connected to a dedicated system for data acquisition. Current ECoG recordings in birds are usually made with metallic wire electrodes placed on the dura surface though a hole on the skull. This approach is not reliable for long term acquisitions (a few days) as the electrodes may generate signal artefacts and cause bleeding. Recently, flexible polymer electrodes have been proposed to avoid the stiffness of the metal wire and to improve compliance with brain surface. The electrodes are fabricated on a 75µm thick polyimide film substrate. Gold lines are used as conductive wires to read the brain potentials and transfer them to the acquisition system. To protect and isolate gold tracks, a protective spinnable polyimide layer (Hitachi PI2610) is subsequently deposited. Then, an aluminium hard mask is deposited and patterned by a lithographic step, to protect and to open a window by oxygen plasma etch in the protective layers, so that the gold pads are exposed. Finally, the electrodes are ready and are detached from the carrier tape. Preliminary insertion tests have showed the feasibility of flexible electrodes insertion in the chicken brain.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11568/862322
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