Biodegradable oxide synaptic transistors gated by a biopolymer electrolyte

Biodegradable oxide synaptic transistors were fabricated on a graphene coated PET substrate. An acid doped chitosan-based biopolymer electrolyte is used as the gate dielectric. With the acid doping, a high proton conductivity of similar to 7.6 x 10(-4) S cm(-1) and a big electric-double-layer capacitance of similar to 1.0 mu F cm(-2) are observed for the biopolymer electrolyte. The fabricated oxide synaptic transistor exhibits good transistor performances, such as a low operation voltage of 1.0 V, a high field-effect mobility of similar to 5.4 cm(2) V-1 s(-1), a high on/off ratio of similar to 3.1 x 10(6) and a low subthreshold swing of similar to 80 mV decade(-1). With the unique proton gating behaviors, synaptic functions, such as excitatory post-synaptic current, paired-pulse facilitation and synaptic filtering were mimicked. Furthermore, the proposed oxide synaptic transistor could be dissolved in water in a short time. We believe that the proposed biodegradable synaptic transistors could provide new opportunities for low cost, portable green'' neuromorphic electronics.