RESUMO
We have measured the flow of gas through single ion track pores in a polymer film using a mass spectroscopy technique. The pores are 12 µm long with diameters in the range of 50-1000 nm, and the flow was driven by pressure drops in the range 0-30 atm. When the mean free path is large compared to the pore diameter (large Knudsen number Kn), the flow rate is proportional to the pressure drop and the pore radius R cubed, and is consistent with a model of diffusive scattering at the pore walls. For Kn≤0.1, the hydrodynamic conductance increases, as predicted by standard kinetic theory models, and finally approaches the conventional Poiseuille value with zero slip length.
Assuntos
Biofísica/métodos , Espectrometria de Massas/métodos , Polímeros/química , Algoritmos , Difusão , Gases , Cinética , Microfluídica , Modelos Estatísticos , Modelos Teóricos , Nanotecnologia , Pressão , TemperaturaRESUMO
High surface charges of polymer pore walls and applied electric fields can lead to the formation and subsequent dissolution of precipitates in nanopores. These precipitates block the pore, leading to current fluctuations. We present an extended Poisson-Nernst-Planck system which includes chemical reactions of precipitation and dissolution. We discuss the mathematical modeling and present 2D numerical simulations.
