2, Stanford University, Stanford, California, United States
3, Seoul National University, Seoul, , Korea (the Republic of)
We report our recent progress in printed organic nanofiber-based neuromorphic and deformable electronics. Precisely controlled organic nanofibers are promising elements for upcoming innovative electronics such as brain-inspired computation and memory, light-weight wearable electronics and biomedical electronics based on their advantages of low-cost solution printing process, high speed and large scale fabrication, high-resolution (< 1μm) patterning, and so on. We reported organic nanofiber-based neuromorphic synapses which emulated important working principles of a biological synapse, e.g., excitatory post-synaptic current (EPSC), inhibitory post-synaptic current (IPSC), paired-pulse facilitation (PPF), short-term plasticity (STP), long-term plasticity (LTP) and spike-timing dependent plasticity (STDP). Electrochemical synaptic transistor arrays with nano-feature size were produced based on aligned organic semiconducting nanofibers and ion-gel dielectric which mimic fiber-like morphology of neurons and biological synaptic cleft. These properties are promising for neuromorphic computation and memory, and the devices would serve as building blocks of future neuromorphic systems. We also recently developed aligned organic semiconducting nanofiber-based deformable electronics which are impervious to mechanical influence when mounted on the surface of dynamically-changing soft matter. Our deformable field-effect transistors can be easily deformed by applied strains (both 100% tensile and compressive strains). The mechanical durability of nanofiber can be further significantly increased by simply re-engineering the geometric structure of the nanofiber. The deformable transistors withstood 100% uniaxial stretching with minimal change of electrical properties, even after a 3D volume change (> 1700% and back to original state) of a rubber balloon. The deformable transistors robustly operated on a mechanically-dynamic soft matter surface e.g. a pulsating balloon that mimics a beating animal heart, which demonstrates potential of the deformable transistor for future biomedical applications.