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Wang X.,University of Victoria | Werner S.,Institute for Bioprocessing and Analytical Measurement Techniques | Weiss T.,Institute for Bioprocessing and Analytical Measurement Techniques | Liefeith K.,Institute for Bioprocessing and Analytical Measurement Techniques | Hoffmann C.,Institute for Bioprocessing and Analytical Measurement Techniques
RSC Advances | Year: 2012

Controlled drug delivery is highly desired for many medicinal cases where time and spatial dependency is required. The present paper provides a promising but also simple molecular architecture for photoinduced release of chemical compounds with primary amines based on one-and two-photon absorption. Silane coupling to the surface and biotin/streptavidin chemistry ensure the stability of the system. © 2012 The Royal Society of Chemistry.


PubMed | Institute for Bioprocessing and Analytical Measurement Techniques, Friedrich - Schiller University of Jena and Jena University Hospital
Type: | Journal: Colloids and surfaces. B, Biointerfaces | Year: 2016

Occlusion by thrombosis due to the absence of the endothelial cell layer is one of the most frequent causes of failure of artificial vascular grafts. Bioinspired surface structures may have a potential to reduce the adhesion of platelets contributing to hemostasis. The aim of this study was to investigate the hemodynamic aspects of platelet adhesion, the main cause of thrombosis, on bioinspired microstructured surfaces mimicking the endothelial cell morphology. We tested the hypothesis that platelet adhesion is statistically significantly reduced on bioinspired microstructured surfaces compared to unstructured surfaces. Platelet adhesion as a function of the microstructure dimensions was investigated under flow conditions on polydimethylsiloxane (PDMS) surfaces by a combined experimental and theoretical approach. Platelet adhesion was statistically significantly reduced (by up to 78%; p0.05) on the microstructured PDMS surfaces compared to that on the unstructured control surface. Finite element method (FEM) simulations of blood flow dynamic revealed a micro shear gradient on the microstructure surfaces which plays a pivotal role in reducing platelet adhesion. On the surfaces with the highest differences of the shear stress between the top of the microstructures and the ground areas, platelet adhesion was reduced most. In addition, the microstructures help to reduce the interaction strength between fluid and surfaces, resulting in a larger water contact angle but no higher resistance to flow compared to the unstructured surface. These findings provide new insight into the fundamental mechanisms of reducing platelet adhesion on microstructured bioinspired surfaces and may lay the basis for the development of innovative next generation artificial vascular grafts with reduced risk of thrombosis.


Sachs J.,TU Ilmenau | Helbig M.,TU Ilmenau | Herrmann R.,TU Ilmenau | Kmec M.,TU Ilmenau | And 3 more authors.
Ad Hoc Networks | Year: 2014

The vitality of a human being is closely connected to temporal variations of its body geometry. This is quite obvious in the case of walking. But also when resting, the motion of inner organs such as lung or heart causes geometric alterations which may be registered by high-resolution ultra-wideband radar. Since the radio waves radiated by such radars are absolutely harmless, they may be deployed for monitoring of resident activities helping to ensure health, safety, and well-being of aged or needy people. These waves may also penetrate most of building materials and snow which makes them useful to detect earthquake and avalanche survivors, too. The most challenging task is the registration of respiration activity of an unconscious person. The principle of breathing motion detection by radar is explained and the major handicaps as well as appropriate counter measures are discussed. The possible structure of a survivor and residential injury detection radar system is considered and some results from field trials are summarized. © 2011 Elsevier B.V. All rights reserved.


Cimpan M.R.,University of Bergen | Mordal T.,University of Bergen | Scholermann J.,University of Bergen | Allouni Z.E.,University of Bergen | And 2 more authors.
Journal of Physics: Conference Series | Year: 2013

Impedance-based assays can constitute a reliable alternative to the conventional methods used in nanotoxicology due to the important advantages of being label-free and monitoring the cells in real-time. In this study, the suitability of impedance-monitoring for the screening of nanoparticle (NP)-induced cytotoxicity was assessed. The effect of titanium dioxide (TiO 2)-NPs on cellular proliferation, viability, spreading, and detachment from substrate was evaluated by continuous impedance-based measurements made with an xCELLigence system. Fibroblasts seeded in microelectrode-embedded E-plates were exposed to spherical anatase nano-TiO 2 (5, 10, and 40 nm in diameter) for up to 120 h. An alternative excitation signal (20 mV control voltage amplitude) was applied at 10, 25, and 50 kHz to the microelectrodes in the E-plates. Cells attached to the electrode surfaces act as insulators and lead to an increase in impedance. For validating the impedance-method, Trypan Blue exclusion and ultrahigh resolution imaging (URI) were employed. The general trend observed was a decrease in impedance following exposure to TiO2-NPs. Impedance-based results were in most instances in accordance with those from the Trypan Blue exclusion and URI assays indicating that the impedance-based approach has merit. Further studies are needed to validate it as a high-throughput method for evaluating NPs' cytotoxicity. © IOP Publishing Ltd 2013.


Wessel J.,Ihp Microelectronics | Schmalz K.,Ihp Microelectronics | Gastrock G.,Institute for Bioprocessing and Analytical Measurement Techniques | Cahill B.P.,Institute for Bioprocessing and Analytical Measurement Techniques | Meliani C.,Ihp Microelectronics
Journal of Physics: Conference Series | Year: 2013

Using a microfluidic system based on PTFE tubes, experimental results of contactless and label-free characterization techniques of yeast cell cultivation are presented. The PTFE tube has an inner diameter of 0.5 mm resulting in a sample volume of 2 μ1 for 1 cm sample length. Two approaches (at frequencies around 7 GHz and 240 GHz) are presented and compared in terms of sensitivity and applicability. These frequency bands are particularly interesting to gain information on the permittivity of yeast cells in Glucose solution. Measurements from 240 GHz to 300 GHz were conducted with a continuous wave spectrometer from Toptica. At 7 GHz band, measurements have been performed using a rat-race based characterizing system realized on a printed circuit board. The conducted experiments demonstrate that by selecting the phase as characterization parameter, the presented contactless and label-free techniques are suitable for cell cultivation monitoring in a PTFE pipe based microfluidic system.


Zaikov E.,Institute for Bioprocessing and Analytical Measurement Techniques
4th Microwave and Radar Week MRW-2010 - 11th International Radar Symposium, IRS 2010 - Conference Proceedings | Year: 2010

In this paper hardware and software aspects of detection and localization of people by their breathing are discussed. Separately, the problem of non-stationary clutter is considered. All the proposed algorithms are supported by measurement examples.


Schneider R.,University of Leipzig | Przybyl J.,University of Leipzig | Pliquett U.,Institute for Bioprocessing and Analytical Measurement Techniques | Hermann M.,Kaiserin Elisabeth Spital | And 6 more authors.
American Journal of Surgery | Year: 2010

Background: Despite conventional neuromonitoring, the recurrent laryngeal nerve (RLN) is still at risk for damage during thyroid surgery. The feasibility of continuous RLN monitoring by vagal nerve (VN) stimulation with a new anchor electrode should be shown, and electromyographic signal alterations of stressed RLN were analyzed to be alerted to imminent nerve failure whereby the nerve damage becomes reversible. Methods: VN stimulation was achieved in 23 pigs. Sensed signals were analyzed and stored as real-time audio/video feedback EMG system. RLN was stressed by mechanical and thermal injury; signal alterations were evaluated. Results: VNs were successfully real-time stimulated by using the anchor electrode. No complications or side effects during stimulation were detected. RLN injury led to an alteration of signal amplitude and latency period but signal restitution after injury. Conclusions: Real-time monitoring of the RLN is technically feasible to perceive imminent nerve failure. The anchor electrode was safely and easy to handle. Its implementation is being tested in an ongoing clinical trial. © 2010 Elsevier Inc. All rights reserved.


Cahill B.P.,Institute For Bioprocessing And Analytical Measurement Techniques
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011

Digital microfluidics utilises discrete droplets to increase the throughput of chemical and biological assays. There is a great need for sensing techniques that can help automate droplet handing. This work aims to illustrate by means of finite element modelling the factors that affect the measurement of droplet impedance in a thin-walled glass capillary. These include modelling the effect of varying capillary wall thickness, electrode spacing, electrode area, droplet size, shielding and droplet conductivity. The simulation is performed using COMSOL finite element analysis software. The model serves to aid the optimization of the measurement system for application in the measurement of the presence/absence of droplets as well as their chemical and biological content. © 2011 SPIE.


Moller S.,Institute for Bioprocessing and Analytical Measurement Techniques | Pliquett U.,Institute for Bioprocessing and Analytical Measurement Techniques | Hoffmann C.,Institute for Bioprocessing and Analytical Measurement Techniques
RSC Advances | Year: 2012

The incorporation of photoactive molecules in thin layers enables photoinduced changes in wettability, e.g. azobenzenes, or micropatterning by deprotection of functional groups, e.g. applying nitroveratryl compounds. This paper describes a synthetic route for obtaining an azobenzene with a silane anchor. The chemical synthesis, including all intermediates, is characterized by NMR and IR. The photoisomerization of all products was investigated by UV/Vis spectroscopy. Ellipsometry and contact angle measurements give information about monolayers of the synthesized organosilanes. © 2012 The Royal Society of Chemistry.


PubMed | Institute for Bioprocessing and Analytical Measurement Techniques and Fraunhofer Institute for Physical Measurement Techniques
Type: Review | Journal: Sensors (Basel, Switzerland) | Year: 2016

Evanescent field sensors based on waveguide surfaces play an important rolewhere high sensitivity is required. Particularly tantalum pentoxide (TaO) is a suitablematerial for thin-film waveguides due to its high refractive index and low attenuation.Many label-free biosensor systems such as grating couplers and interferometric sensors aswell as fluorescence-based systems benefit from this waveguide material leading toextremely high sensitivity. Some biosensor systems based on TaO waveguides alreadytook the step into commercialization. This report reviews the various detection systems interms of limit of detection, the applications, and the suitable surface chemistry.

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