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Dissertation Defense

ASIC-Integrated, High Density Flexible Electrode Array with Less Tissue Damage and Long-Term Reliability

Kyounghwan Na
3316 EECS BuildingMap


In this work, I proposed a long-term reliable, high density flexible electrode array. A novel T-shaped diamond shuttle to deliver a flexible array with less tissue damage was designed and fabricated. T-shaped diamond shuttles penetrated the intact dura mater for rat brain and the epineurium for feline dorsal root ganglia and resulted in excellent signal quality single units from the delivered flexible array. A reliable polyimide based neural electrode array with low impedance was developed by metal-polyimide adhesion improvement using a novel adhesive layer of TiO2 and by a wafer-level roughening process. This array showed more than 6 months of lifetime through accelerated lifetime test. A 256-ch polyimide based neural electrode was designed, fabricated by implementing 0.5µm line/space metal traces and then packaged. A 256-ch recording ASIC with circuit-under-pad configuration for high density was connected to the backend of the probe with 75µm pad pitch by flip-chip bonding using anisotropic conductive film. The form factor of the overall package was significantly reduced compared to the recently reported work. This neural probe system was also verified by in vivo recording.

Chair: Professor Euisik Yoon