Searching lab on a chip literature: the need for a glossary of terms and concepts in a multidisciplinary environment

This paper investigates the problem of searching literature in a multidisciplinary environment. It is found that much relevant literature is not found because other disciplines use a different terminology, different units, or slightly different (but related) concepts. The paper suggests some approaches to enhance interdisciplinary understanding and improve exchange of ideas and literature

Constructing a proton titration curve from ion-step measurements, applied to a membrane with adsorbed protein

A new measuring method is described for obtaining a proton titration curve. The curve is obtained from a microporous composite membrane, consisting of polystyrene beads in an agarose matrix, with lysozyme molecules adsorbed to the bead surface. The membrane is incorporated into a sensor system by deposition on a silicon chip with a pH-sensitive ion-sensitive field effect transistor (ISFET) located in the middle of a Ag/AgCl electrode. The actual measurement is performed by creating a stepwise change in the salt concentration of the bathing electrolyte (the ion step) and measuring the ISFET potential versus the Ag/AgCl electrode. This potential shows a transient change in the ion step, which indicates a transient pH change in the membrane. This procedure is repeated at a series of pH values. Equations are presented to calculate the proton titration curve of the membrane from the amplitude and duration of the measured transients. Measurements show qualitative agreement between the curves obtained and equilibrium titration experiments on the same system

Nanotechnology for membranes, filters and sieves

This mini-review is dedicated to the use of nanotechnology for membranes, filters and sieves. With the advent of nanotechnology researchers have acquired an unprecedented freedom to sculpt device geometry almost down to the molecular scale. Such structures can now replace the gels, membranes and sieves of random pore structure that are commonly used in such separations. In this mini-review we want to highlight the impact that this development has had in the area of separation by filtering and sieving, where exciting developments are taking place. To do this we will first present the basic phenomena that determine separation in these devices, together with some historical background. Subsequently we will look at the micro- and nanomachined membranes, filters and sieves that have been manufactured in the past few years, and highlight advances resulting from the use of nanotechnology. In particular, the ability of nanotechnology to produce spatially anisotropic sieving structures suitable for continuous flow operation is seen as a new and exciting development. The invention of structures that sculpt hydrodynamic flow lines in order to perform continuous filtering is another important development. In general continuous flow operation is desirable in nanoscale systems since sampling (either of a detection signal or of the separated substances) can be time-integrated, thus improving the detection limit

Osmosis and pervaporation in polyimide submicron microfluidic channel structures

Osmosis and pervaporation of water through the roof of all-polyimide channels of 500 nm height is described. The phenomena cause both a liquid flow in the channels and a concentration change of dissolved salt. Both effects are amplified due to the thin channel roof and the small channel height. Osmotic movement of demineralized water was observed towards a salt solution and towards ethanol and isopropanol. Water movement by pervaporation was observed from a salt solution towards the atmosphere. Flow velocities of up to 70 �?��m/s were generated in the channels. The results are in accordance with predictions from the solution-diffusion model for membrane transport. The observed phenomena can be applied in a nanofluidic osmotic pump or for an osmotic or pervaporative concentrator