The long-term goal of this line of research is to develop a disruptive polymer “memristor”. Specifically, the effect of chemical structure on the conformationally induced switching properties of a range of non-conjugated polymers with pendant carbazoles was investigated with a specific goal to create a polymer that exhibits a tailorable multi-state conductance appropriate for being employed as a synaptic substitute. One of the fundamental characteristics of synaptic plasticity in biological neural networks is spike-timing-dependent-plasticity (STDP) and its replication in a synthetic model is critical for emulating biological systems. STDP has been demonstrated in multiple species, including humans, and is considered the basis for cognitive learning. The STDP response of an ITO/poly(11-(9H-carbazol-9-yl)undecyl methacrylate) (PUMA)/aluminum memristor is presented in Figure 1 where the ITO and aluminum electrodes were designated the presynaptic and postsynaptic neuron, respectively. The potentiation and depression of the synaptic weight could be modulated with a variation in the timing offset of the two pulses. In Figure 1, when the presynaptic spike arrives before the postsynaptic spike there is a potentiation of the synaptic weight while depression occurs when the presynaptic spike arrives after the postsynaptic spike. This response is similar to a Asymmetric Hebbian Learning Rule, where leads to long-term potentiation (LTP) of the synapse and leads to long-term depression (LTD) of the synapse. This change in conductivity with voltage pulses is a basic attribute for building a synaptic substitute.

Conductance variability in non-conjugated polymers: Memristors in neuromorphic applications

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.