Ionic transport phenomena in nanofluidics: Experimental and theoretical study of the exclusion-enrichment effect on a chip

In nanometer-sized apertures with charged surfaces, the extension of the electrical double layer results in the electrostatic exclusion of co-ions and enrichment in counterions, which affects the permselectivity of such structures. A modeling of this phenomenon is proposed and is compared with quantitative measurements of the ionic permeability change of a Pyrex nanoslit at low ionic strength. The comparison of experimental results with theoretical predictions justifies that electrostatic forces are the governing forces in nanofluidics

Glass-based nanofluidic device for biomolecule preconcentration study

The fabrication of a hybrid micro/nano-fluidic device to study electropreconcentration of biomolecules is presented. A nanoslit surrounded by glass is formed between two access microchannels and an “H” configuration bio-analysis system is developed. The optimized know-how for this biochip fabrication is transferred and the key steps are discussed. Fluorescence spatiotemporal profile in the preconcentration area is recorded and quantitatively analyzed. The reliability of the applied technology for studies of charged biomolecule transport phenomena across nanochannels is proven giving two examples for different preconcentration geometries

Fast microfluidic temperature control for high resolution live cell imaging

One major advantage of using genetically tractable model organisms such as the fission yeast Schizosaccharomyces pombe is the ability to construct temperature-sensitive mutations in a gene. The resulting gene product or protein behaves as wildtype at permissive temperatures. At non-permissive or restrictive temperatures the protein becomes unstable and some or all of its functions are abrogated. The protein regains its function when returning to a permissive temperature. In principle, temperature-sensitive mutation enables precise temporal control of protein activity when coupled to a fast temperature controller. Current commercial temperature control devices do not have fast switching capability over a wide range of temperatures, making repeated temperature changes impossible or impractical at the cellular timescale of seconds or minutes. Microfabrication using soft-lithography is emerging as a powerful tool for cell biological research. We present here a simple disposable polydimethylsiloxane (PDMS) based microfluidic device capable of reversibly switching between 5 °C and 45 °C in less than 10 s. This device allows high-resolution live cell imaging with an oil immersion objective lens. We demonstrate the utility of this device for studying microtubule dynamics throughout the cell cycle. © 2011 The Royal Society of Chemistry.link_to_subscribed_fulltex