Nonlinear Dynamics of Nanopore Current Oscillations

几乎所有的电化学体系在一定的外参数范围内都存在振荡行为。基于膜的电化学振荡器被研究为振荡生物过程的模型系统，以及神经元中动作电位的传播。由动力系统计划支持的研究的智力价值是制备和建模基于单个锥形纳米孔的新型膜电化学振荡器。在强可溶性盐溶液（例如氯化钾）中，锥形纳米孔充当分子电流整流器。当微量的难溶物种，如CaHPO4存在时，系统经历了一个有趣的转变，从直流电流准周期电流振荡时，达到临界膜电压。外部参数将被识别，允许调谐的范围内的几分之一Hz到几十Hz的电流振荡的频率。离子电流振荡也将稳定几个小时。实验数据将进行非线性动力学分析，以区分随机噪声从这些纳米系统中的确定性混沌，并为后者的情况下，如吸引子维数和李雅普诺夫指数的特征将从记录中提取。非线性动力学分析将并行进行的离子电流振荡的现象学建模，使用耦合的化学动力学微分方程。该项目的成功将导致一种新型电化学振荡器的制备和建模，这种振荡器可以用作离子电路、人工细胞和传感系统的工作元件。该研究还将导致基于纳米孔的电化学振荡器的非线性动力学表征，并更好地理解在生理水基条件下远离平衡的系统。该项目的教育计划侧重于为加州大学欧文分校的初中和高中学生组织纳米技术实践活动。这些推广活动将与UCI学校研究和信息技术合作伙伴关系（SPIRIT）计划合作进行。在非线性动力学工具，电化学，表面研究和生物物理学的跨学科培训将提供给本科生和研究生。

Oscillatory behavior has been observed for almost all electrochemical systems in a certain range of external parameters. Electrochemical oscillators based on membranes are studied as model systems of oscillatory biological processes, and propagation of action potential in neurons. The intellectual merit of the research supported by the Dynamical Systems Program is to prepare and model a new type of membrane electrochemical oscillators based on single tapered-cone shaped nanopores. In strongly soluble salt solutions e.g. potassium chloride, conical nanopores act as molecular current rectifiers. When traces of sparingly soluble species, such as CaHPO4 are present, the system undergoes an intriguing transformation from DC current flow to quasiperiodic current oscillations when a critical membrane voltage is reached. External parameters will be identified that allow for tuning the frequency of current oscillations in the range between fractions of Hz up to several tens of Hz. The ion current oscillations will also be stable for several hours. The experimental data will be subjected to nonlinear dynamics analysis in order to distinguish random noise from deterministic chaos in these nanosystems, and for the latter case characteristics such as attractor dimension and Lyapunov exponents will be extracted from the recordings. The nonlinear dynamics analysis will be performed in parallel to the phenomenological modeling of ion current oscillations using coupled chemical kinetics differential equations. Universal character of this dissipative system far from equilibrium will be investigated as well.Success of the project will lead to preparation and modeling of a new type of electrochemical oscillators, which could be applied as a working element of an ionic circuit, artificial cells, and sensory systems. The research will also result in nonlinear dynamics characterization of nanopore based electrochemical oscillators, and in better understanding of systems that function far from equilibrium in physiological, water based conditions. Education program of this project is focused on organizing hands-on activities for middle and high school students in nanotechnology at UC Irvine. The outreach activities will be done in collaboration with the UCI School Partnership in Research and Information Technology (SPIRIT) program. Interdisciplinary training in nonlinear dynamics tools, electrochemistry, surface studies, and biophysics will be offered to undergraduate and gradate students.