@article{FrotscherMuanghongDursunetal.2016, author = {Frotscher, Ralf and Muanghong, Danita and Dursun, G{\"o}zde and Goßmann, Matthias and Temiz Artmann, Ayseg{\"u}l and Staat, Manfred}, title = {Sample-specific adaption of an improved electro-mechanical model of in vitro cardiac tissue}, series = {Journal of Biomechanics}, volume = {49}, journal = {Journal of Biomechanics}, number = {12}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0021-9290 (Print)}, doi = {10.1016/j.jbiomech.2016.01.039}, pages = {2428 -- 2435}, year = {2016}, abstract = {We present an electromechanically coupled computational model for the investigation of a thin cardiac tissue construct consisting of human-induced pluripotent stem cell-derived atrial, ventricular and sinoatrial cardiomyocytes. The mechanical and electrophysiological parts of the finite element model, as well as their coupling are explained in detail. The model is implemented in the open source finite element code Code_Aster and is employed for the simulation of a thin circular membrane deflected by a monolayer of autonomously beating, circular, thin cardiac tissue. Two cardio-active drugs, S-Bay K8644 and veratridine, are applied in experiments and simulations and are investigated with respect to their chronotropic effects on the tissue. These results demonstrate the potential of coupled micro- and macroscopic electromechanical models of cardiac tissue to be adapted to experimental results at the cellular level. Further model improvements are discussed taking into account experimentally measurable quantities that can easily be extracted from the obtained experimental results. The goal is to estimate the potential to adapt the presented model to sample specific cell cultures.}, language = {en} } @article{GossmannFrotscherLinderetal.2016, author = {Goßmann, Matthias and Frotscher, Ralf and Linder, Peter and Bayer, Robin and Epple, U. and Staat, Manfred and Temiz Artmann, Ayseg{\"u}l and Artmann, Gerhard}, title = {Mechano-pharmacological characterization of cardiomyocytes derived from human induced pluripotent stem cells}, series = {Cellular physiology and biochemistry}, volume = {38}, journal = {Cellular physiology and biochemistry}, number = {3}, publisher = {Karger}, address = {Basel}, issn = {1421-9778 (Online)}, doi = {10.1159/000443124}, pages = {1182 -- 1198}, year = {2016}, abstract = {Background/Aims: Common systems for the quantification of cellular contraction rely on animal-based models, complex experimental setups or indirect approaches. The herein presented CellDrum technology for testing mechanical tension of cellular monolayers and thin tissue constructs has the potential to scale-up mechanical testing towards medium-throughput analyses. Using hiPS-Cardiac Myocytes (hiPS-CMs) it represents a new perspective of drug testing and brings us closer to personalized drug medication. Methods: In the present study, monolayers of self-beating hiPS-CMs were grown on ultra-thin circular silicone membranes and deflect under the weight of the culture medium. Rhythmic contractions of the hiPS-CMs induced variations of the membrane deflection. The recorded contraction-relaxation-cycles were analyzed with respect to their amplitudes, durations, time integrals and frequencies. Besides unstimulated force and tensile stress, we investigated the effects of agonists and antagonists acting on Ca²⁺ channels (S-Bay K8644/verapamil) and Na⁺ channels (veratridine/lidocaine). Results: The measured data and simulations for pharmacologically unstimulated contraction resembled findings in native human heart tissue, while the pharmacological dose-response curves were highly accurate and consistent with reference data. Conclusion: We conclude that the combination of the CellDrum with hiPS-CMs offers a fast, facile and precise system for pharmacological, toxicological studies and offers new preclinical basic research potential.}, language = {en} } @article{FischerSelverGezeretal.2015, author = {Fischer, Felix and Selver, M. Alper and Gezer, Sinem and Dicle, Oguz and Hillen, Walter}, title = {Systematic Parameterization, Storage, and Representation of Volumetric DICOM Data}, series = {Journal of Medical and Biological Engineering}, volume = {35}, journal = {Journal of Medical and Biological Engineering}, number = {6}, publisher = {Springer}, address = {Berlin}, issn = {2199-4757}, doi = {10.1007/s40846-015-0097-5}, pages = {709 -- 723}, year = {2015}, language = {en} } @article{HauserKotliarTholenetal.2015, author = {Hauser, C. and Kotliar, Konstantin and Tholen, S. and Hasenau, A. and Suttmann, Y. and Renders, L. and Heemann, U. and Baumann, M. and Schmaderer, C.}, title = {Dynamische retinale Gef{\"a}ßreaktion bei H{\"a}modialysepatienten}, series = {Nieren- und Hochdruckkrankheiten}, volume = {44}, journal = {Nieren- und Hochdruckkrankheiten}, number = {11}, publisher = {Dustri-Verlag}, address = {Oberhaching}, issn = {0300-5224}, doi = {10.5414/NHX01743a}, pages = {480 -- 480}, year = {2015}, language = {de} } @article{HamadBilattoAdlyetal.2016, author = {Hamad, E. M. and Bilatto, S. E. R. and Adly, N. Y. and Correa, D. S. and Wolfrum, B. and Sch{\"o}ning, Michael Josef and Offenh{\"a}usser, A. and Yakushenko, A.}, title = {Inkjet printing of UV-curable adhesive and dielectric inks for microfluidic devices}, series = {Lab on a Chip}, volume = {16}, journal = {Lab on a Chip}, number = {1}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1473-0189}, doi = {10.1039/C5LC01195G}, pages = {70 -- 74}, year = {2016}, abstract = {Bonding of polymer-based microfluidics to polymer substrates still poses a challenge for Lab-On-a-Chip applications. Especially, when sensing elements are incorporated, patterned deposition of adhesives with curing at ambient conditions is required. Here, we demonstrate a fabrication method for fully printed microfluidic systems with sensing elements using inkjet and stereolithographic 3D-printing.}, language = {en} } @article{MuribYeapEurlingsetal.2016, author = {Murib, M. S. and Yeap, W. S. and Eurlings, Y. and Grinsven, B. van and Boyen, H.-G. and Conings, B. and Michiels, L. and Ameloot, M. and Carleer, R. and Warmer, J. and Kaul, P. and Haenen, K. and Sch{\"o}ning, Michael Josef and Ceuninck, W. de and Wagner, P.}, title = {Heat-transfer based characterization of DNA on synthetic sapphire chips}, series = {Sensors and Actuators B: Chemical}, volume = {230}, journal = {Sensors and Actuators B: Chemical}, number = {230}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0925-4005}, doi = {10.1016/j.snb.2016.02.027}, pages = {260 -- 271}, year = {2016}, abstract = {In this study, we show that synthetic sapphire (Al₂O₃), an established implant material, can also serve as a platform material for biosensors comparable to nanocrystalline diamond. Sapphire chips, beads, and powder were first modified with (3-aminopropyl) triethoxysilane (APTES), followed by succinic anhydride (SA), and finally single-stranded probe DNA was EDC coupled to the functionalized layer. The presence of the APTES-SA layer on sapphire powders was confirmed by thermogravimetric analyis and Fourier-transform infrared spectroscopy. Using planar sapphire chips as substrates and X-ray photoelectron spectroscopy (XPS) as surface-sensitive tool, the sequence of individual layers was analyzed with respect to their chemical state, enabling the quantification of areal densities of the involved molecular units. Fluorescence microscopy was used to demonstrate the hybridization of fluorescently tagged target DNA to the probe DNA, including denaturation- and re-hybridization experiments. Due to its high thermal conductivity, synthetic sapphire is especially suitable as a chip material for the heat-transfer method, which was employed to distinguish complementary- and non-complementary DNA duplexes containing single-nucleotide polymorphisms. These results indicate that it is possible to detect mutations electronically with a chemically resilient and electrically insulating chip material.}, language = {en} } @article{OberlaenderKirchnerKeusgenetal.2015, author = {Oberl{\"a}nder, Jan and Kirchner, Patrick and Keusgen, Michael and Sch{\"o}ning, Michael Josef}, title = {Strategies in developing thin-film sensors for monitoring aseptic food processes : Theoretical considerations and investigations of passivation materials}, series = {Electrochimica Acta}, volume = {183}, journal = {Electrochimica Acta}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0013-4686}, doi = {10.1016/j.electacta.2015.06.126}, pages = {130 -- 136}, year = {2015}, abstract = {The sterilization of packages in aseptic food processes is highly significant to maintain a consumer-safe product with extended shelf-life. Today, the sterilization of food packages is predominantly accomplished by gaseous hydrogen peroxide (H2O2) in combination with heat. In order to monitor this sterilization process, calorimetric gas sensors as differential set-up of two platinum temperature sensors representing a catalytically active (additionally deposition of MnO2) and a passive segment have been recently developed. The temperature rise of the exothermic decomposition serves as an indicator of the present H2O2 concentration. In the present work, a theoretical approach considering the sensor's thermochemistry and physical transport phenomena was formulated to evaluate the temperature rise based on the energy content of gaseous H2O2. In a further part of this work, three polymers have been analyzed with respect to their application as passivation materials. The examined polymers are photoresist SU-8, perfluoroalkoxy (PFA) and fluorinated ethylene propylene (FEP). Thermal analyses by means of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) have been conducted to determine the operation limits of the polymers. The overall chemical resistance and stability of the polymers against the harsh environmental conditions during the sterilization process have been examined by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR).}, language = {en} } @article{MiyamatoSakakitaWagneretal.2015, author = {Miyamato, Ko-ichiro and Sakakita, Sakura and Wagner, Torsten and Sch{\"o}ning, Michael Josef and Yoshinobu, Tatsuo}, title = {Application of chemical imaging sensor to in-situ pH imaging in the vicinity of a corroding metal surface}, series = {Electrochimica Acta}, volume = {183}, journal = {Electrochimica Acta}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0013-4686}, doi = {10.1016/j.electacta.2015.07.184}, pages = {137 -- 142}, year = {2015}, abstract = {The chemical imaging sensor was applied to in-situ pH imaging of the solution in the vicinity of a corroding surface of stainless steel under potentiostatic polarization. A test piece of polished stainless steel was placed on the sensing surface leaving a narrow gap filled with artificial seawater and the stainless steel was corroded under polarization. The pH images obtained during polarization showed correspondence between the region of lower pH and the site of corrosion. It was also found that the pH value in the gap became as low as 2 by polarization, which triggered corrosion.}, language = {en} } @article{SchusserKrischerBaeckeretal.2015, author = {Schusser, Sebastian and Krischer, Maximillian and B{\"a}cker, Matthias and Poghossian, Arshak and Wagner, Patrick and Sch{\"o}ning, Michael Josef}, title = {Monitoring of the Enzymatically Catalyzed Degradation of Biodegradable Polymers by Means of Capacitive Field-Effect Sensors}, series = {Analytical Chemistry}, volume = {87}, journal = {Analytical Chemistry}, number = {13}, publisher = {ACS Publications}, address = {Washington, DC}, issn = {1520-6882}, doi = {10.1021/acs.analchem.5b00617}, pages = {6607 -- 6613}, year = {2015}, abstract = {Designing novel or optimizing existing biodegradable polymers for biomedical applications requires numerous tests on the effect of substances on the degradation process. In the present work, polymer-modified electrolyte-insulator-semiconductor (PMEIS) sensors have been applied for monitoring an enzymatically catalyzed degradation of polymers for the first time. The thin films of biodegradable polymer poly(d,l-lactic acid) and enzyme lipase were used as a model system. During degradation, the sensors were read-out by means of impedance spectroscopy. In order to interpret the data obtained from impedance measurements, an electrical equivalent circuit model was developed. In addition, morphological investigations of the polymer surface have been performed by means of in situ atomic force microscopy. The sensor signal change, which reflects the progress of degradation, indicates an accelerated degradation in the presence of the enzyme compared to hydrolysis in neutral pH buffer media. The degradation rate increases with increasing enzyme concentration. The obtained results demonstrate the potential of PMEIS sensors as a very promising tool for in situ and real-time monitoring of degradation of polymers.}, language = {en} } @article{KowalskiLinderZierkeetal.2016, author = {Kowalski, Julia and Linder, Peter and Zierke, S. and Wulfen, B. van and Clemens, J. and Konstantinidis, K. and Ameres, G. and Hoffmann, R. and Mikucki, J. and Tulaczyk, S. and Funke, O. and Blandfort, D. and Espe, Clemens and Feldmann, Marco and Francke, Gero and Hiecker, S. and Plescher, Engelbert and Sch{\"o}ngarth, Sarah and Dachwald, Bernd and Digel, Ilya and Artmann, Gerhard and Eliseev, D. and Heinen, D. and Scholz, F. and Wiebusch, C. and Macht, S. and Bestmann, U. and Reineking, T. and Zetzsche, C. and Schill, K. and F{\"o}rstner, R. and Niedermeier, H. and Szumski, A. and Eissfeller, B. and Naumann, U. and Helbing, K.}, title = {Navigation technology for exploration of glacier ice with maneuverable melting probes}, series = {Cold Regions Science and Technology}, journal = {Cold Regions Science and Technology}, number = {123}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0165-232X}, doi = {10.1016/j.coldregions.2015.11.006}, pages = {53 -- 70}, year = {2016}, abstract = {The Saturnian moon Enceladus with its extensive water bodies underneath a thick ice sheet cover is a potential candidate for extraterrestrial life. Direct exploration of such extraterrestrial aquatic ecosystems requires advanced access and sampling technologies with a high level of autonomy. A new technological approach has been developed as part of the collaborative research project Enceladus Explorer (EnEx). The concept is based upon a minimally invasive melting probe called the IceMole. The force-regulated, heater-controlled IceMole is able to travel along a curved trajectory as well as upwards. Hence, it allows maneuvers which may be necessary for obstacle avoidance or target selection. Maneuverability, however, necessitates a sophisticated on-board navigation system capable of autonomous operations. The development of such a navigational system has been the focal part of the EnEx project. The original IceMole has been further developed to include relative positioning based on in-ice attitude determination, acoustic positioning, ultrasonic obstacle and target detection integrated through a high-level sensor fusion. This paper describes the EnEx technology and discusses implications for an actual extraterrestrial mission concept.}, language = {en} }