Ordered porous Materials

Drift Ratchet

We present a first experimental realization of a ratchet concept based on macroporous silicon. Applying a periodic pressure profile with zero mean value causes a periodic flow of water and suspended particles through ratchet-shaped channels. A net motion for the colloidal particles is observed although the liquid itself is not moving on average. The pressure dependence agrees well with microscopic calculations and exhibits the predicted current inversion with a remarkably narrow transition region. The highly efficient transport due to many ratchet stages in series and the potentially high throughput due to the millions of pores acting in parallel are the main advantages of the new device.





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