Unraveling the physics of nanofluidic phenomena at the single-molecule level

Fornasiero, Francesco¹ 

[1] Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

关键词: CARBON NANOTUBES;    CATIONS;    GRAPHITE;    CHLORIDES;    NANOFLUIDICS;    ENERGY STORAGE;    ELECTRIC CURRENTS;    WALLS;    ELECTROLYTES;    INTERACTIONS;    MEMBRANES;    POLARIZATION;    COMPUTERIZED SIMULATION;    TRANSIENTS;    TRANSLOCATION;    IONIC CONDUCTIVITY;    OSMOSIS;    POTASSIUM IONS;   

DOI  :  10.2172/1240944
RP-ID  :  LLNL--TR-678200
PID  :  OSTI ID: 1240944
Others  :  TRN: US1600692

学科分类：纳米科学和纳米技术

美国|英语

来源: SciTech Connect

【 摘 要 】

Despite groundbreaking potential in a broad application space, several nanofluidic phenomena remain poorly understood. Toward advancing the understanding of fluid behavior under nanoscale confinement, we developed a novel, ideal platform for fundamental molecular transport studies, in which the fluidic channel is a single carbon nanotube (CNT). CNTs offer the advantage of simple chemistry and structure, which can be synthetically tuned with nanometer precision and accurately modeled. With combined experimental and computational approaches, we demonstrated that CNT pores with 1-5 nm diameters conduct giant ionic currents that follow an unusual sublinear electrolyte concentration dependence. The large magnitude of the ionic conductance appears to originate from a strong electro-osmotic flow in smooth CNT pores. First-principle simulations suggest that electro-osmotic flow arises from localized negative polarization charges on carbon atoms near a potassium (K⁺) ion and from the strong cation-graphitic wall interactions, which drive K⁺ ions much closer to the wall than chlorides (Cl^-). Single-molecule translocation studies reveal that charged molecules may be distinguished from neutral species on the basis of the sign of the transient current change during their passage through the nanopore. Together with shedding light on a few controversial questions in the CNT nanofluidics area, these results may benefit LLNL???s Security Mission by providing the foundation for the development of advanced single-molecule detection system for bio/chem/explosive analytes. In addition, these experimental and computational platforms can be applied to advance fundamental knowledge in other fields, from energy storage and membrane separation to superfluid physics.