Session:

Organic material-based conformable electronics are optimal candidates for components of bioelectronic circuits due to their inherent flexibility and soft nature. We have shown that internally ion-gated organic electrochemical transistors (IGTs) operate by leveraging ion reservoirs inside their channels to dramatically improve the operation speed and integration capacity of this ion driven transistor. In order to establish IGTs as versatile building blocks of bioelectronics, it is critical to establish fabrication strategies to enable IGT-based high-density integrated circuits for creation of fully implantable, wireless, and battery-free devices. Here, we report a scalable, self-contained, and integrable sub-micron internal ion-gated organic electrochemical transistor with vertical channel (v-IGT). Owing to the sub-micron channel size, v-IGTs can operate in the MHz range, surpassing any other electrochemical device while maintaining a high amplification. Furthermore, we analytically and experimentally derived the non-linear relationship between transistor speed and contact area as a function of gate and channel capacitance. The device is encapsulated using long-term implantable grade (parylene-C) material ensuring operational stability of over 1 year. We also developed a micron-scale perforation strategy to ensure intact hydration paths for transistor channels while maintaining effective isolation of densely packed adjacent transistors and minimizing potential for cross-talk and gate current leakage. The presence of this hydration via does not cause a detriment to the device characteristics due to the hydrophilicity and sufficient containment of ion reservoirs in the channel. We fabricated a conformable v-IGT-based array with 155k transistor/cm2, highlighting the viability and feasibility of IGTs as transistor architecture for a majority of flexible electronics applications. We further showcase their functionality by creating high-gain multi-stage amplifiers, oscillators, and multiplexers. Finally, we created a novel wireless, battery-free strategy for electrophysiological signal acquisition, processing and transmission that employs v-IGTs and ionic communication (IC). The wirelessly-powered v-IGTs were able to acquire and modulate neurophysiological data in-vivo and transmit them across the dermis, eliminating the need for any hard Si-based electronics in the implant.

Co-Author(s): Zifang Zhao (Columbia University), Jennifer Gelinas (Columbia University), Dion Khodagholy (Columbia University)

Claudia Cea

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