@article{ArcaTeddeSrameketal.2013, author = {Arca, Francesco and Tedde, Sandro F. and Sramek, Maria and Rauh, Julia and Lugli, Paolo and Hayden, Oliver}, title = {Interface Trap States in Organic Photodiodes}, series = {Scientific Reports}, volume = {3}, journal = {Scientific Reports}, doi = {10.1038/srep01324}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-131507}, pages = {1324}, year = {2013}, abstract = {Organic semiconductors are attractive for optical sensing applications due to the effortless processing on large active area of several \(cm^2\), which is difficult to achieve with solid-state devices. However, compared to silicon photodiodes, sensitivity and dynamic behavior remain a major challenge with organic sensors. Here, we show that charge trapping phenomena deteriorate the bandwidth of organic photodiodes (OPDs) to a few Hz at low-light levels. We demonstrate that, despite the large OPD capacitances of similar to 10 nF \(cm^{-2}\), a frequency response in the kHz regime can be achieved at light levels as low as 20 nW \(cm^{-2}\) by appropriate interface engineering, which corresponds to a 1000-fold increase compared to state-of-the-art OPDs. Such device characteristics indicate that large active area OPDs are suitable for industrial sensing and even match medical requirements for single X-ray pulse detection in the millisecond range.}, language = {en} } @article{LotzKiesewetterSchmidetal.2018, author = {Lotz, C. and Kiesewetter, L. and Schmid, F. F. and Hansmann, J. and Walles, H. and Groeber-Becker, F.}, title = {Replacing the Draize eye test: impedance spectroscopy as a 3R method to discriminate between all GHS categories for eye irritation}, series = {Scientific Reports}, volume = {8}, journal = {Scientific Reports}, number = {15049}, doi = {10.1038/s41598-018-33118-2}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-177492}, year = {2018}, abstract = {Highly invasive animal based test procedures for risk assessment such as the Draize eye test are under increasing criticism due to poor transferability for the human organism and animal-welfare concerns. However, besides all efforts, the Draize eye test is still not completely replaced by alternative animal-free methods. To develop an in vitro test to identify all categories of eye irritation, we combined organotypic cornea models based on primary human cells with an electrical readout system that measures the impedance of the test models. First, we showed that employing a primary human cornea epithelial cell based model is advantageous in native marker expression to the primary human epidermal keratinocytes derived models. Secondly, by employing a non-destructive measuring system based on impedance spectroscopy, we could increase the sensitivity of the test system. Thereby, all globally harmonized systems categories of eye irritation could be identified by repeated measurements over a period of 7 days. Based on a novel prediction model we achieved an accuracy of 78\% with a reproducibility of 88.9\% to determine all three categories of eye irritation in one single test. This could pave the way according to the 3R principle to replace the Draize eye test.}, language = {en} } @article{VogelRueckertGreineretal.2023, author = {Vogel, P. and R{\"u}ckert, M. A. and Greiner, C. and G{\"u}nther, J. and Reichl, T. and Kampf, T. and Bley, T. A. and Behr, V. C. and Herz, S.}, title = {iMPI: portable human-sized magnetic particle imaging scanner for real-time endovascular interventions}, series = {Scientific Reports}, volume = {13}, journal = {Scientific Reports}, doi = {10.1038/s41598-023-37351-2}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-357794}, year = {2023}, abstract = {Minimally invasive endovascular interventions have become an important tool for the treatment of cardiovascular diseases such as ischemic heart disease, peripheral artery disease, and stroke. X-ray fluoroscopy and digital subtraction angiography are used to precisely guide these procedures, but they are associated with radiation exposure for patients and clinical staff. Magnetic Particle Imaging (MPI) is an emerging imaging technology using time-varying magnetic fields combined with magnetic nanoparticle tracers for fast and highly sensitive imaging. In recent years, basic experiments have shown that MPI has great potential for cardiovascular applications. However, commercially available MPI scanners were too large and expensive and had a small field of view (FOV) designed for rodents, which limited further translational research. The first human-sized MPI scanner designed specifically for brain imaging showed promising results but had limitations in gradient strength, acquisition time and portability. Here, we present a portable interventional MPI (iMPI) system dedicated for real-time endovascular interventions free of ionizing radiation. It uses a novel field generator approach with a very large FOV and an application-oriented open design enabling hybrid approaches with conventional X-ray-based angiography. The feasibility of a real-time iMPI-guided percutaneous transluminal angioplasty (PTA) is shown in a realistic dynamic human-sized leg model.}, language = {en} }