We have fabricated porous membranes using a parylene encapsulated vertically aligned forest of multi-walled carbon nanotubes (MWCNTs, about 7nm inner diameter). The transport of charged particles in electrolyte through these membranes was studied by applying electric field and pressure. Under an electric field in the range of 4.4×10 4Vm 1, electrophoresis instead of electroomosis is found to be the main mechanism for ion transport. Small molecules and 5nm gold nanoparticles can be driven through the membranes by an electric field. However, small biomolecules, like DNA oligomers, cannot. Due to the weak electric driving force, the interactions between charged particles and the hydrophobic CNT inner surface play important roles in the transport, leading to enhanced selectivity for small molecules. Simple chemical modification on the CNT ends also induces an obvious effect on the translocation of single strand DNA oligomers and gold nanoparticles under a modest pressure (<294Pa).
ASJC Scopus subject areas
- Materials Science(all)
- Mechanics of Materials
- Mechanical Engineering
- Electrical and Electronic Engineering