Georgios Spyropoulos1 Jeremy Savarin1 Jennifer Gelinas1 Dion Khodagholy1

1, Columbia University, New York, New York, United States

As our understanding of the brain’s physiology and pathology progresses, increasingly sophisticated technologies are required to advance discoveries in neuroscience and develop more effective approaches to treat brain diseases.
To meet this challenge, we propose a novel transistor architecture that provides an efficient interface with biological substrates, especially neural networks, through its channel’s intrinsic ion mobility. Because independent electronic gating can be applied to these transistors, they can be incorporated into integrated circuits, unlike their electrolyte-gated counterparts. The channel consists of a composite film based on highly conductive poly(3,4-ethylenedioxythiophene) doped with polystyrene sulfonate (PEDOT:PSS) enriched with D-sorbitol. At the gate electrode, an ion exchange membrane serves as ion conductor. To determine an optimal transistor configuration and material composition, we microfabricated transistor arrays of varying geometrical parameters. In doing so, we were able to extract conductivity, contact resistance, and electrochemical impedance values for all the critical interfaces of various composites. Furthermore, output characteristics and current temporal response of each configuration revealed the key driving physical parameters and provided insight into optimization of the device for various applications.
The resulting optimal transistors were tested as electroencephalography (EEG) interface and amplifier circuitry and compared with organic electrochemical transistors and surface electrodes showed promising signal-to-noise ratio and spatio-temporal resolution.