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Biomedical subjects

Dirk Janasek

Publications and source records attributed to Dirk Janasek.

6 recordsLinked to original sources
PubMed2006

Scaling and the design of miniaturized chemical-analysis systems.

Micrometre-scale analytical devices are more attractive than their macroscale counterparts for various reasons. For example, they use smaller volumes of reagents and are therefore cheaper, quicker and less hazardous to use, and more environmentally appealing. Scaling laws compare the relative performance of a system as the dimensions of the system change, and can predict the operational success of miniaturized chemical separation, reaction and detection devices before they are fabricated. Some devices designed using basic principles of scaling are now commercially available, and opportunities for miniaturizing new and challenging analytical systems continue to arise.

Animals↗
PubMed2006

Isotachophoresis in free-flow using a miniaturized device.

For the first time, we report a miniaturized approach for isotachophoresis employing the technique of free-flow electrophoresis. Using a micromachined separation chamber with a volume of 200 nL, a sample mixture of fluorescein, eosin G, and acetylsalicylic acid was separated, stacked, and concentrated in less than a minute. Additionally, an isotachophoretic separation of a reaction mixture of myoglobin and fluoresceinisothiocyanate as a fluorescence label has shown the potential of this method for on-line sample preparation.

Journal Article↗
PubMed2003

Sub-second isoelectric focusing in free flow using a microfluidic device.

Using a microfabricated chip with a bed volume of 0.2 microL we demonstrate the validity of the scaling laws for molecular mass transport of isoelectric focusing (IEF) in free flow. Nano- or microlitre sample volumes can be concentrated within 430 ms by a factor of up to 400. These very fast performances make the chip applicable to proteomic analysis and for continuous monitoring of biochemical processes.

Angiotensin I↗
PubMed2002

Ruthenium/rhodium modified gold electrodes for the amperometric detection of hydrogen peroxide at low potentials.

Electrodes of ruthenium/rhodium deposited as thin layers on gold foils were investigated. Ruthenium layers were radio frequency (r.f.) magnetron sputtered and the rhodium layers were made by vacuum evaporation. Hydrogen peroxide could be detected using the cathodic reduction at potentials lower than +170 mV or the anodic oxidation at higher potentials. Under flow injection conditions, H(2)O(2) was detected between 1 and 1000 micro M at a potential of -100 mV and between 2 and 500 micro M at a potential of +250 mV vs. Ag/AgCl/0.4 M KCl. The electrodes also showed high operational stability and selectivity against many electroactive substances. The selectivity against dissolved oxygen was investigated.

Journal Article↗