Nanofluidics

Jan Eijkel is Associate Professor in microfluidics and nanofluidics in the BIOS/Lab on a Chip group (MESA+ Institute for Nanotechnology, University of Twente, The Netherlands). He studied pharmacy (University of Amsterdam) and theology (University of Utrecht) and obtained a Ph.D. in biosensor research at the University of Twente. His research interests include physical and colloid chemistry, electrochemistry, microseparation methods, and microplasma physics and applications. Geen abstract beschikbaa

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

Energy from streaming current and potential

It is investigated how much energy can be delivered by a streaming current source. A streaming current and subsequent streaming potential originate when double layer charge is transported by hydrodynamic flow. Theory and a network model of such a source is presented and initial experimental results are given, showing a supplied power of 20 nW obtained by a pressure difference of 1 atm over a glass porous plug, using a 1-mM KCl solution. It is indicated how the rather low mechanical-to-electrical energy conversion efficiency can be increased

Adapting to a changing highschool population

This paper reports the recent changes in the EE Bachelor program at the University of Twente. Recent generations of freshman students exhibited a lack in mathematics skills and the ability to grasp the physics behind the equations. By starting of the curriculum with a new course “Introduction to electronics and electrical engineering (IEEE)�? we have managed to solve the issue of lacking entry levels while simultaneously eliminating the unmotivated or under skilled students in a very early stage in their studies

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

Proteomics-on-a-chip for Biomarker discovery

In proteomics research still two-dimensional gel electrophoresis (2D-GE) is currently used for biomarker discovery. We applied free flow electrophoresis (FFE) separation technology combined with biomolecular interaction sensing using Surface Plasmon Resonance (SPR) imaging in an integrated proteomics-on-a-chip device as a proof of concept for biomarker discovery

A thin-film magnetoresistive angle detector

An overview is given of the results of our research on a contactless angle detector based on the anisotropic magnetoresistance effect (AMR effect) in a permalloy thin film. The results of high-temperature annealing treatment of the pemalloy film are discussed. Such a treatment suppresses the effects of the uniaxial magnetic anisotropy that is present in a permalloy thin film and increases the AMR effect, thus improving the detector signal. The performance of the detector throughout a temperature range of 20 to 120 °C and the results of heat treatment at 125 °C for 1 week have been tested