Description:

Researchers have created a nanoscale ion pump by punching a tiny hole in a plastic sheet and applying an oscillating electric field.  The group hopes that the device will eventually help explain ion pumps and channels in biological cells, the inspirations for their work.
To produce such holes, they shot high-energy gold atoms into thin plastic foils. Using a very low intensity beam, they could gouge essentially isolated tracks in the material. Chemical etching then expanded each tunnel in the plastic into a cone that went from 2 nanometers wide on one side to 500 nanometers on the other.  The researchers placed the film in a solution of potassium chloride and measured its current-voltage characteristics as they applied an AC voltage across the sheet. And as they had hoped, the pores pumped potassium ions to one side, increasing their concentration there at the expense of the other side.  

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