Emergence of winner-takes-all connectivity paths in random nanowire networks

Nanowire networks are promising memristive architectures for neuromorphic applications due to their connectivity and neurosynaptic-like behaviours. Here, we demonstrate a self-similar scaling of the conductance of networks and the junctions that comprise them. We show this behavior is an emergent property of any junction-dominated network. A particular class of junctions naturally leads to the emergence of conductance plateaus and a “winner-takes-all” conducting path that spans the entire network, and which we show corresponds to the lowest-energy connectivity path. The memory stored in the conductance state is distributed across the network but encoded in specific connectivity pathways, similar to that found in biological systems. These results are expected to have important implications for development of neuromorphic devices based on reservoir computing

"Effective Electrode Length Enhances Electrical Activation of Nanowire Networks: Experiment and Simulation"

Networks comprised of randomly oriented overlapping nanowires offer the possibility of simple fabrication on a variety of substrates, in contrast with the precise placement required for devices with single or aligned nanowires. Metal nanowires typically have a coating of surfactant or oxide that prevents aggregation, but also prevents electrical connection. Prohibitively high voltages can be required to electrically activate nanowire networks, and even after activation many nanowire junctions remain non-conducting. Non-electrical activation methods can enhance conductivity but destroy the memristive behavior of the junctions that comprise the network. We show through both simulation and experiment that electrical stimulation, microstructured electrode geometry, and feature scaling can all be used to manipulate the connectivity and thus, electrical conductivity of networks of silver nanowires with a non-conducting polymer coating. More generally, these results describe a strategy to integrate nanomaterials into controllable, adaptive macroscale materials

Effective Electrode Length Enhances Electrical Activation of Nanowire Networks: Experiment and Simulation

Tout comme l’on a proposé d’intégrer anthropologie et histoire dans différents champs interdisciplinaires (« anthropologie historique », « ethno-histoire »), des phénomènes similaires de rapprochement sont identifiables à l’intérieur de la musicologie où les branches historique (« musicologie historique ») et anthropologique (« musicologie comparée » et « ethnomusicologie ») ont essayé de s’intégrer dans ce qu’on a appelé « ethnomusicologie historique ». Le propos de cet article est de déplacer la discussion du niveau interdisciplinaire au supra-disciplinaire, l’argument étant que l’interdisciplinarité n’est pas la solution pour des problèmes déterminés par un cadre de pensée qui structure tout un ensemble de disciplines. Nous nous livrons alors à l’examen du contexte de formation des disciplines modernes et de leurs présupposés partagés, spécialement en ce qui touche à l’étude de la musique médiévale.In keeping with the attempt to integrate anthropology and history in interdisciplinary study programmes such as “historical anthropology” or “ethno-history,” it has been proposed that the historical and anthropological branches of musicology should be united in the broad interdisciplinary field of “historical ethnomusicology.” This would include “historical musicology,” and what was initially termed “comparative musicology,” which eventually developed into “ethnomusicology”. This article argues that it is necessary to move the discussion from an inter- to a supra-disciplinary level, since the interdisciplinary approach cannot address issues determined by a framework of thought that structures all disciplines which may be brought together. This article examines the context in which the modern disciplines were shaped and their shared presuppositions, with a particular focus on the study of medieval music.Così come è stato proposto di integrare antropologia e storia in diversi campi disciplinari, (« antropologia storica », « etnostoria »), è possibile riscontrare dei fenomeni analoghi di accostamento nell’ambito della musicologia, nella quale si è cercato in particolare di integrare la sezione storica (« musicologia storica ») e quella antropologica (« musicologia comparata » e « etnomusicologia ») in quel che si è definito « etnomusicologia storica ». L’obiettivo di questo articolo è di spostare l’accento del dibattito dal livello interdisciplinare al livello supra-disciplinare, nella convinzione che l’interdisciplinarietà non possa essere la soluzione a quei problemi che sono posti dall’orizzonte concettuale che struttura l’insieme delle discipline che si pongono in relazione. Si offrirà pertanto un esame del contesto di formazione delle discipline moderne e dei loro presupposti condivisi, in riferimento particolare allo studio della musica medievale

Resistance of Single Ag Nanowire Junctions and Their Role in the Conductivity of Nanowire Networks

Networks of silver nanowires appear set to replace expensive indium tin oxide as the transparent conducting electrode material in next generation devices. The success of this approach depends on optimizing the material conductivity, which until now has largely focused on minimizing the junction resistance between wires. However, there have been no detailed reports on what the junction resistance is, nor is there a known benchmark for the minimum attainable sheet resistance of an optimized network. In this paper, we present junction resistance measurements of individual silver nanowire junctions, producing for the first time a distribution of junction resistance values and conclusively demonstrating that the junction contribution to the overall resistance can be reduced beyond that of the wires through standard processing techniques. We find that this distribution shows the presence of a small percentage (6%) of high-resistance junctions, and we show how these may impact the performance of network-based materials. Finally, through combining experiment with a rigorous model, we demonstrate the important role played by the network skeleton and the specific connectivity of the network in determining network performance

Effective Electrode Length Enhances Electrical Activation of Nanowire Networks: Experiment and Simulation

Networks comprised of randomly oriented overlapping nanowires offer the possibility of simple fabrication on a variety of substrates, in contrast with the precise placement required for devices with single or aligned nanowires. Metal nanowires typically have a coating of surfactant or oxide that prevents aggregation, but also prevents electrical connection. Prohibitively high voltages can be required to electrically activate nanowire networks, and even after activation many nanowire junctions remain nonconducting. Nonelectrical activation methods can enhance conductivity but destroy the memristive behavior of the junctions that comprise the network. We show through both simulation and experiment that electrical stimulation, microstructured electrode geometry, and feature scaling can all be used to manipulate the connectivity and thus electrical conductivity of networks of silver nanowires with a nonconducting polymer coating. More generally, these results describe a strategy to integrate nanomaterials into controllable, adaptive macroscale materials