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Abstract: Tunable nanopores in elastomeric membranes have been used to study thedependence of ionic current blockade rate on the concentration andelectrophoretic mobility of particles in aqueous suspensions. A range ofnanoparticle sizes, materials and surface functionalities has been tested.Using pressure-driven flow through a pore, the blockade rate for 100 nmcarboxylated polystyrene particles was found to be linearly proportional toboth transmembrane pressure controlled between 0 and 1.8 kPa and particleconcentration between 7 x 10^8 and 4.5 x 10^10 mL^-1. This result can beaccurately modelled using Nernst-Planck transport theory. Using only an appliedpotential across a pore, the blockade rates for carboxylic acid and aminecoated 500 nm and 200 nm silica particles were found to correspond to changesin their mobility as a function of the solution pH. Scanning electronmicroscopy and confocal microscopy have been used to visualise changes in thetunable nanopore geometry in three dimensions as a function of appliedmechanical strain. The pores observed were conical in shape, and changes inpore size were consistent with ionic current measurements. A zone of inelasticdeformation adjacent to the pore has been identified as critical in the tuningprocess.



Author: G R Willmott, R Vogel, S S C Yu, L G Groenewegen, G S Roberts, D Kozak, W Anderson, M Trau

Source: https://arxiv.org/







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