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.
