Electroosmotic Flow in Nanofluidic Channels
نویسندگان
چکیده
We report the measurement of electroosmotic mobilities in nanofluidic channels with rectangular cross sections and compare our results with theory. Nanofluidic channels were milled directly into borosilicate glass between two closely spaced microchannels with a focused ion beam instrument, and the nanochannels had half-depths (h) of 27, 54, and 108 nm and the same half-width of 265 nm. We measured electroosmotic mobilities in NaCl solutions from 0.1 to 500 mM that have Debye lengths (κ(-1)) from 30 to 0.4 nm, respectively. The experimental electroosmotic mobilities compare quantitatively to mobilities calculated from a nonlinear solution of the Poisson-Boltzmann equation for channels with a parallel-plate geometry. For the calculations, ζ-potentials measured in a microchannel with a half-depth of 2.5 μm are used and range from -6 to -73 mV for 500 to 0.1 mM NaCl, respectively. For κh > 50, the Smoluchowski equation accurately predicts electroosmotic mobilities in the nanochannels. However, for κh < 10, the electrical double layer extends into the nanochannels, and due to confinement within the channels, the average electroosmotic mobilities decrease. At κh ≈ 4, the electroosmotic mobilities in the 27, 54, and 108 nm channels exhibit maxima, and at 0.1 mM NaCl, the electroosmotic mobility in the 27 nm channel (κh = 1) is 5-fold lower than the electroosmotic mobility in the 2.5 μm channel (κh = 100).
منابع مشابه
Fabrication and electroosmotic flow measurements in micro- and nanofluidic channels
An easy method for fabricating microand nanofluidic channels, entirely made of a thermally grown silicon dioxide is presented. The nanochannels are up to 1-mm long and have widths and heights down to 200 nm, whereas the microfluidic channels are 20-lm wide and 4.8-lm high. The nanochannels are created at the interface of two silicon wafers. Their fabrication is based on the expansion of growing...
متن کاملDesign and fabrication of a multilayered polymer microfluidic chip with nanofluidic interconnects via adhesive contact printing.
The design and fabrication of a multilayered polymer micro-nanofluidic chip is described that consists of poly(methylmethacrylate) (PMMA) layers that contain microfluidic channels separated in the vertical direction by polycarbonate (PC) membranes that incorporate an array of nanometre diameter cylindrical pores. The materials are optically transparent to allow inspection of the fluids within t...
متن کاملEffects of Polymer Length and Salt Concentration on the Transport of ssDNA in Nanofluidic Channels.
Electrokinetic phenomena in micro/nanofluidic channels have attracted considerable attention because precise control of molecular transport in liquids is required to optically and electrically capture the behavior of single molecules. However, the detailed mechanisms of polymer transport influenced by electroosmotic flows and electric fields in micro/nanofluidic channels have not yet been eluci...
متن کاملSurface charge, electroosmotic flow and DNA extension in chemically modified thermoplastic nanoslits and nanochannels.
Thermoplastics have become attractive alternatives to glass/quartz for microfluidics, but the realization of thermoplastic nanofluidic devices has been slow in spite of the rather simple fabrication techniques that can be used to produce these devices. This slow transition has in part been attributed to insufficient understanding of surface charge effects on the transport properties of single m...
متن کامل