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This study uses negative dielectrophoresis and AC electroosmosis as a driving mechanism and presents an electrically driven microconcentrator that concentrates the sample in the region exterior to the electrodes (termed as exterior-electrode electrically driven microconcentrator in this paper). The proposed microconcentrator uses a 3-D face-to-face electrode pair; the top electrode is a relatively large planar electrode, and the bottom electrode is formed with three to six long and thin electrodes connected into an open ring. The sample is brought to the vicinity of the open electrode at the bottom by electroosmotic flow; then, negative dielectrophoresis is used to push the sample away from the electrode and concentrate it in the region surrounded by the open ring electrode. Concentration using an exterior-electrode electrically driven microconcentrator offers promise for convenient use in conjunction with relevant detection systems. The results indicate that for the proposed exterior-electrode electrically driven microconcentrator, the optimal frequency is 100 kHz and the optimal voltage is 13 Vp-p . The corner concentration process at the corners of the bottom open electrodes enables the multi-corner electrodes to exhibit better concentration results than that exhibited by semicircular-shaped electrodes. The concentration performance is most favorable when the shape of the open electrode at the bottom is a five-vertex electrode, enabling a concentration enhancement factor of 55 times for a latex particle solution and 11 times for E. coli. The experimental results also demonstrate that the concentration phenomenon in this study is not induced by non-specific adsorption and can be repeated multiple times.

In recent studies related to bioelectronics, significant efforts have been made to form 3D electrodes to increase the effective surface area or to optimize the transfer of signals at tissue-electrode interfaces. Although bioelectronic devices with 2D and flat electrode structures have been used extensively for monitoring biological signals, these 2D planar electrodes have made it difficult to form biocompatible and uniform interfaces with nonplanar and soft biological systems (at the cellular or tissue levels). Especially, recent biomedical applications have been expanding rapidly toward 3D organoids and the deep tissues of living animals, and 3D bioelectrodes are getting significant attention because they can reach the deep regions of various 3D tissues. An overview of recent studies on 3D bioelectronic devices, such as the use of electrical stimulations and the recording of neural signals from biological subjects, is presented. Subsequently, the recent developments in materials and fabrication processing to 3D micro- and nanostructures are introduced, followed by broad applications of these 3D bioelectronic devices at various in vitro and in vivo conditions.

A planar electrode (collector) is immersed into a weakly magnetized discharge plasma column. Positive voltage steps are applied to the collector and time resolved measurements of the plasma response are performed by emissive probes using standard boxcar technique. On the emissive probe characteristics an interesting phenomenon is observed: a few μs after the application of the voltage step to the collector (time depends on the distance between the collector and the probe), the emissive probe starts to collect additional positive current in the potential region between plasma potentials of the high and low potential plasma. This phenomenon is investigated experimentally. We give a possible qualitative explanation that additional positive current collection is due to a combination of an interaction between the collector and the probe and space charge effects of positive ions around the probe.

Carbon-electrode dielectrophoresis (carbon-DEP) is demonstrated here as an alternative to more traditional DEP techniques. Carbon-DEP combines advantages of metal-electrode and insulator-based DEP by using low-cost fabrication techniques and low voltages for particle manipulation. The use of 3-D electrodes is proved to yield significant advantages over the use of traditional planar electrodes. This paper details the fabrication of dense arrays of tall high aspect ratio carbon electrodes on a transparent fused-silica substrate. The shrinkage of the SU-8 structures during carbonization is characterized and a design tool for future devices is provided. Applications of carbon electrodes in DEP are then detailed and include particle positioning, high-throughput filtering and cell focusing using positive-DEP. Manipulated cells include Saccharomyces cerevisiae and Drosophila melanogaster. The advantages and disadvantages of carbon-DEP are discussed at the end of this work.

An einem selbstgebauten Plasmaplanaratzreaktor wurde das Trockenatzen von dunnen Schichten organischer Polymere im Sauerstoffplasma untersucht. Die gefundenen strukturbedingten Unterschiede in den Atzraten der Polymere stimmen mit Literaturangaben uberein. Die Resultate des Plasmaatzens hangen stark von den experimentellen Bedingungen ab. A planar electrode reactor for dry etching was constructed, and thin films of organic polymers were etched in oxygen plasma. The differences of etching rates measured for polymers of different structures are in agreement with literature data. The results of plasma etching strongly depend on experimental conditions.

Electrolysis of metal ions in dilute solutions using vertical planar electrodes results in low recovery. Therefore, an electrolytic cell arranged concentrically with extended cathode surface areas was designed to improve the rate of mass transfer. Three types of gold solutions obtained from industrial sites were used. Despite an initial gold level of 110 mg l −1 , the electrolytic cell was effective in reducing the gold concentration to as low as 0.1 mg l −1 .