Margit Lenninger

High current density 3D electrodes manufactured by technical embroidery

Embroidery techniques allow flexible construction of 3D electrodes, which can form the conductive backbone in ultra-thick electrodes. 3D structures were manufactured by combination of stainless steel yarn, Cu wire, polyester (PES) fabric and Cu/Ni-coated PES web. Alkaline solutions of 9,10-anthraquinone-1,5-disulfonate or 1,2-dihydroxy-9,10-anthraquinone-3-sulfonate (Alizarin Red S) were used as reversible redox systems to characterise the electrodes by voltammetry in a flow cell. The height of the diffusion-limited current for the reversible cathodic reduction of the 9,10-anthraquinoide group was used as measure for the electrode performance. Compared to plane Cu electrodes, an increase in the diffusion-limited cathodic current density by factor 3–5 was obtained.

Multi-chamber electroosmosis using textile reinforced agar membranes--A promising concept for the future of hemodialysis.

Renal replacement therapy options are limited to hemodialysis and peritoneal dialysis (70% of US patients) or renal transplantation. Diffusion processes are the main physico-chemical principle behind hemodialysis. An alternative way to achieve liquid flow through membranes bases on the electroosmotic flow which is observed as electrokinetic phenomenon in porous membranes which bear surface charges. Agar consists of the non-ionic agarose and the negatively charged agaropectine thus an electroosmotic flux is observed in analytical electrophoresis. In this study the potential electroosmosis on textile reinforced agar membranes as separation method was investigated. Using a five-chamber electrolysis cell and an agar membrane/cellulose fabric composite an intensive electroosmotic flow of 1-2 ml cm(2) h(-1) at 100 mA cell current could be observed. The movement of cations in the negatively charged agar structure led to an intensive electroosmotic flux, which also transported uncharged molecules such as urea, glucose through the membrane. Separation of uncharged low molecular weight molecules is determined by the membrane characteristic. The transport of ions (K(+), PO4(3-), creatinine) and uncharged molecules (urea, glucose) in electroosmotic separation experiments was monitored using a pH 5.5 phosphate electrolyte with the aim to assess the overall transport processes in the electrochemical cell. The results demonstrate the potential of the method for filtration of biological fluids in the absence of external pressure or high shear rates.

Particle Release from Woven Cellulosic Substrates

The linting propensity of a woven cellulosic substrate is investigated as a function of substrate characteristics and of different parameters in the test environment. The results from the linting propensity tests parallel those observed in liquid—solid extraction processes, where solutes are extracted from a matrix of other insoluble solids by selective dissolution in a liquid. The equation quantifying solute extraction in such systems also proves to be a good fit for the linting propensities observed in this work. Hence, it maybe possible to regard linting phenomena as extraction processes and to use the equation quantifying solute extraction to predict substrate linting as a function of both substrate characteristics and the test environment.