Flexible and biocompatible memristive devices are particularly attractive for bioelectronic systems due to the interest in improving computing capabilities and the motivation to interface electronics with biological systems including drug delivery, neural interfaces and biosensors. Structures made of more unorthodox, organic material can address different issues due to their characteristics: flexibility, conformability, biocompatibility and simple and low-cost fabrication. It has been observed that gating graphene/ionic liquid (IL) devices leads to the formation of an electrical double layer (a thin layer of ions with a thickness of a few nanometers) at the graphene/IL interface due to the local potential difference which also controls the local conductivity. This structure provides a memristive mechanism based on a dynamic p-n junction formation along the channel. Motivated by this memristive behavior, graphene/IL devices were assembled with the aim of demonstrating memristive behavior and associative learning. This work investigates memristive properties of flexible graphene/ IL devices on polymer substrates. The I-V characteristics of these novel devices and switching mechanism are investigated. Two distinct topologies (single input, single output and double input, single output) of devices are manufactured and tested to mimic conditioning. It is observed that the application of voltage pulse trains of both positive and negative polarities increases the device conductance and allows larger currents to pass after repetitive excitation. This characteristic was exploited to condition devices and emulate associative learning.
忆阻系统是由Leon Chua和Sung Mo Kang于1976年提出的，作为具有记忆效应的二端无源非线性动力系统的模型。这样的系统最初被证明是相关的神经元中的动作电位的建模方面的Hodgkin-Huxley模型，最近，到薄膜材料，如TiO 2-x提出的非易失性电阻存储器的建模。然而，在过去的50年中，各种3端非无源动态器件也被证明表现出与忆阻系统模型预测的记忆效应类似的记忆效应。本文扩展了原始忆阻系统框架，以纳入3端非无源器件，并解释了这种动态系统模型对1）Widrow-Hoff忆阻器，2）浮栅存储单元和3）纳米离子FET的适用性。关键词-忆阻系统，忆阻器，双稳态，突触晶体管，非线性动态系统
The role of ion transport phenomena in memristive double barrier devices
在这项工作中，我们报告的作用离子输运的双势垒量子力学Al/Al $_2$ O $_3$ /Nb $_{\text{x}}$ O $_{\text{y}}$ /Au忆阻器件的动态行为的数值模拟结合实验测量的基础上。该器件由Al $_2$ O $_3$隧道势垒和Au电极处的半导体金属界面之间的超薄Nb $_{\text{x}}$ O $_{\text{y}}$固态电解质组成。它示出，该设备提供了一些有趣的功能，如固有的电流遵守，一个相对较长的保留时间，并不需要一个初始化步骤的潜在应用。因此，它在高密度随机存取存储器或神经形态混合信号电路中的应用特别有吸引力。然而，阻变的基本物理机制仍然没有完全理解。为了研究电流输运机制和内部原子器件结构之间的相互作用，将集总元件电路模型与用于离子输运的3D动力学Monte Carlo模型一致地耦合。模拟结果表明，Nb $_{\text{x}}$ O $_{\text{y}}$中带电点缺陷的漂移是影响阻变特性的关键因素。它示出了详细的，氧的扩散修改的局部电子界面态，导致在双势垒器件的界面特性的变化。
Contrasting Analog and Digital Resistive Switching Memory Characteristics in Solution-Processed Copper (I) Thiocyanate and Its Polymer Electrolyte Based Memristive Devices
Electric selective activation of memristive interfaces in TaO$_x$-based devices
用于神经形态计算和非传统逻辑操作的新型器件的开发在很大程度上依赖于具有超出标准双极行为和数字开-关状态的功能的良好控制的忆阻系统的制造。在目前的工作中，我们证明了Ta $_2$ O $_5$为基础的设备，它是可能的选择性地激活/去激活两个串联忆阻界面，以获得顺时针或逆时针多级平方电阻回路，只是通过控制（a）所施加的刺激的对称性和所使用的金属电极的性质无关。基于我们彻底的表征，分析和建模，我们表明，这种电行为的物理起源依赖于控制氧空位电迁移之间的三个不同区域的活性钽$_2$ O $_{5-x}$层：一个中央-散装-一个和两个准对称界面减少TaO $_{2-h(y)}$层。我们的器件制造工艺相当简单，因为它意味着只有一种CMOS兼容氧化物-Ta氧化物-和一种金属的室温沉积，这表明有可能以低成本和易于扩展的方式利用这些特性。具有多个模拟中间稳定状态的可调反向电阻回路循环允许模仿生物系统的适应性突触权重，并为非标准逻辑器件提供了潜力。
Direct imaging elucidates ionic memory in two-dimensional nanochannels
The University of Manchester（曼彻斯特大学）；National Graphene Institute, The University of Manchester（曼彻斯特大学国家石墨烯研究所）；EPFL（洛桑联邦理工学院）；Institute of Bioengineering, School of Engineering, EPFL（洛桑联邦理工学院工程学院生物工程系）；Institute of Science and Technology Austria (ISTA)（奥地利科学与技术研究院）；ENS de Lyon, Université de Lyon（里昂高等师范学院，里昂大学）；Laboratoire Photonique Numérique et Nanosciences, Univ. Bordeaux（波尔多大学光子数字与纳米科学实验室）
