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

Eijkel, Jan

Materials Today

English

Eijkel, Jan C.T.

NARCIS 

Nanofluidics

University of Twente Research Information

EDITORIALNanofluidicsJan EijkelPublished online: 15 March 2009# The Author(s) 2009. This article is published with open access at Springerlink.comIt is a pleasure to present this special issue on nanofluidics.Spurred by rapid technological advances in micromachin-ing techniques, the research field of nanofluidics appearedabout ten years ago. Nanofluidics is generally defined asthe study of liquid flow in and around objects of 100 nmand less, and the applications thereof. Of course fluidresearch on this scale had already been studied for manydecades, for example in colloid chemistry, the physics offluids, and membrane science. However, the ability tomanufacture devices with nanoscale precision is new andgave this area such a strong impetus that it came to be seenas a separate discipline.For readers of “Analytical and Bioanalytical Chemistry”it is of great importance to become acquainted withnanofluidics, because most of its applications concern(bio)chemical separation. A number of specific contribu-tions of nanofluidics to separation science can be pin-pointed. To start on the fundamental level, phenomenainvolving nanometer length scales such as the Debye lengthand slip length can be investigated more rigorously.Applications then follow from the improvements in solventand solute handling this brings. Second, nanofluidic studieshave increased our understanding of the mechanismsbehind classical separation methods. Control of dimensionsand geometries down to the nanoscale enables the investi-gation of processes that hitherto were obscured by statisticalvariation of, e.g., surface properties. Third, with regard toapplications, the nanoscale control of geometry has enabledthe exploration of new separation mechanisms. Sievescould be designed with pore shapes and pore chargedistributions that were precisely tuned to exploit specificelectrical, steric, or entropic molecular properties. Further-more the ultrashort diffusion times on the nanoscale enabledseparations based on molecular diffusion rates, e.g. inBrownian ratchets.At present nanofluidic research is mostly explorative andresearchers are still working towards real-life analyticalapplications. Important issues remain, especially concerningthe ultrasmall quantities of analyte involved, which compli-cate detection and post-separation processes. Rapid advan-ces have, however, been made in developing methodssuitable for sensitive detection in nanospaces, for exampleoptical (e.g. surface-enhanced Raman spectrometry) orelectrical (e.g. nanowires and redox cycling).In this special issue you will find a total of seven paperscovering diverse nanofluidic topics. The review by HanGardeniers focuses on the question of whether chemistry innanoscale confinement differs from chemistry in freesolution. Synthetic chemistry and protein folding areconsidered, in addition to analytical applications. Afundamental contribution is given by Frederik Detobel etal., who show that shear-driven chromatography in 120-nmdeep nanochannels offers us the opportunity to studymolecular adsorption by and desorption kinetics of thestationary phase. The contribution by Eric Kalman et al.concerns the properties of a gated membrane, belonging toa promising new class of membranes with tunableproperties. The authors show that conical nanopores witha smallest opening of 6–12 nm can behave either as current-rectifiers or Ohmic resistors, depending on the gatepotential applied. In the work reported in their paperNicolas Durand et al. employed a 50-nm high nano-channel/nanoridge device designed to measure differencesin analyte diffusivity. They show that the device can beAnal Bioanal Chem (2009) 394:383–384DOI 10.1007/s00216-009-2723-yJ. Eijkel (*)EWI/BIOS, MESA+ Institute for Nanotechnology,Twente University,PO Box 217, 7500 AE Enschede, The Netherlandse-mail: J.C.T.Eijkel@el.utwente.nlused to detect rapid protein formation. The theoreticalcontribution of Zi Li et al. proposes a new type of devicewith asymmetric nanocavities, designed to separate rod-likenanoparticles such as short DNA. Interestingly, separationcould be achieved by application of an AC voltage, in otherwords the device has rectifying properties. The paper ofYi-Heng Sen et al. reports on DNA translocation through200 nm by 200 nm PDMS/glass nanochannels usingamperometric detection. Translocation is found to occur onlyabove a certain threshold voltage, which can probably becontributed to an entropic energy barrier. This researchcontributes to possible future nanopore DNA sensors. Finally,Edgar Goluch and co-authors employ electrochemical detec-tion in a nanocavity. Using an interdigitated electrode arrayunder an array of 75-nm high nanochannels, the authorsachieve 100-fold current amplification by using redox cycling.They make an important step towards possible sensingapplications by showing the immunity of the device forinterfering redox-active substances if these are irreversiblydamaged in the process. I wish the reader much inspirationfrom these fascinating contributions to this young field.Open Access This article is distributed under the terms of theCreative Commons Attribution Noncommercial License which per-mits any noncommercial use, distribution, and reproduction in anymedium, provided the original author(s) and source are credited.Jan Eijkel is Associate Professor inmicrofluidics and nanofluidics in theBIOS/Lab on a Chip group (MESA+Institute for Nanotechnology, Univer-sity of Twente, The Netherlands). Hestudied pharmacy (University ofAmsterdam) and theology (Universityof Utrecht) and obtained a Ph.D. inbiosensor research at the Universityof Twente. His research interestsinclude physical and colloid chemis-try, electrochemistry, microseparationmethods, and microplasma physicsand applications.384 J. Eijkel

Nanofluidics

Abstract

Similar works

Full text

Available Versions

NARCIS

University of Twente Research Information