bluuebunny/crossref_metadata_2025_split huggingface dataset:
Usability evaluation of a locomotor therapy device considering different strategies
Authors: Langthaler Sonja , Lassnig Alexander , Baumgartner Christian , Schröttner Jörg 
Published: December 2016

Abstract
Usability of medical devices is one of the main determining factors in preventing use errors in treatment and strongly correlates to patient safety and quality of treatment. This thesis demonstrates the usability testing and evaluation of a prototype for locomotor therapy of infants. Therefore, based on the normative requirements of the EN 62366, a concept combined of evaluation procedures and assessing methods was created to enable extensive testing and analysis of the different aspects of usability. On the basis of gathered information weak points were identified and appropriate measures were presented to increase the usability and operating safety of the locomotor prototype. The overall outcome showed an usability value of 77.4% and an evaluation score of 6.99, which can be interpreted as “satisfactory”.
Hypoxia-on-a-chip
Authors: Busek Mathias , Grünzner Stefan , Steege Tobias , Klotzbach Udo , Sonntag Frank 
Published: December 2016

Abstract
In this work a microfluidic cell cultivation device for perfused hypoxia assays as well as a suitable controlling unit are presented. The device features active components like pumps for fluid actuation and valves for fluid direction as well as an oxygenator element to ensure a sufficient oxygen transfer. It consists of several individually structured layers which can be tailored specifically to the intended purpose. Because of its clearness, its mechanical strength and chemical resistance as well as its well-known biocompatibility polycarbonate was chosen to form the fluidic layers by thermal diffusion bonding. Several oxygen sensing spots are integrated into the device and monitored with fluorescence lifetime detection. Furthermore an oxygen regulator module is implemented into the controlling unit which is able to mix different process gases to achieve a controlled oxygenation. First experiments show that oxygenation/deoxygenation of the system is completed within several minutes when pure nitrogen or air is applied to the oxygenator. Lastly the oxygen input by the pneumatically driven micro pump was quantified by measuring the oxygen content before and after the oxygenator.
Bionic forceps for the handling of sensitive tissue
Authors: Kölle Lucia , Schwarz Oliver 
Published: December 2016

Abstract
Anatomical forceps are used for the handling of sensitive structures in medicine. Structures which are manipulated with these forceps can get damaged or slip out of the grip of the forceps. This paper presents a forceps using the bionic Fin-Ray-Effect inspired by fish-fins in order to handle vulnerable structures in particular. During the process of development, functional models of this forceps were designed, 3D-printed and evaluated.
Experimental studies on 3D printing of barium titanate ceramics for medical applications
Authors: Schult Mark , Buckow Eric , Seitz Hermann 
Published: December 2016

Abstract
The present work deals with the 3D printing of porous barium titanate ceramics. Barium titanate is a biocompatible material with piezoelectric properties. Due to insufficient flowability of the starting material for 3D printing, the barium titanate raw material has been modified in three different ways. Firstly, barium titanate powder has been calcined. Secondly, flow additives have been added to the powder. And thirdly, flow additives have been added to the calcined powder. Finally, a polymer has been added to the three materials and specimens have been printed from these three material mixtures. The 3D printed parts were then sintered at 1320°C. The sintering leads to shrinkage which differs between 29.51–71.53% for the tested material mixtures. The porosity of the parts is beneficial for cell growth which is relevant for future medical applications. The results reported in this study demonstrate the possibility to fabricate porous piezoelectric barium titanate parts with a 3D printer that can be used for medical applications. 3D printed porous barium titanate ceramics can especially be used as scaffold for bone tissue engineering, where the bone formation can be promoted by electrical stimulation.
Patient specific root-analogue dental implants – additive manufacturing and finite element analysis
Authors: Gattinger Johannes , Bullemer Christian N. , Harrysson Ola L. A. 
Published: December 2016

Abstract
Aim of this study was to prove the possibility of manufacturing patient specific root analogue two-part (implant and abutment) implants by direct metal laser sintering. The two-part implant design enables covered healing of the implant. Therefore, CT-scans of three patients are used for reverse engineering of the implants, abutments and crowns. Patient specific implants are manufactured and measured concerning dimensional accuracy and surface roughness. Impacts of occlusal forces are simulated via FEA and compared to those of standard implants.
3D printing – a key technology for tailored biomedical cell culture lab ware
Authors: Schmieder Florian , Ströbel Joachim , Rösler Mechthild , Grünzner Stefan , Hohenstein Bernd , Klotzbach Udo , Sonntag Frank 
Published: December 2016

Abstract
Today’s 3D printing technologies offer great possibilities for biomedical researchers to create their own specific laboratory equipment. With respect to the generation of ex vivo vascular perfusion systems this will enable new types of products that will embed complex 3D structures possibly coupled with cell loaded scaffolds closely reflecting the in-vivo environment. Moreover this could lead to microfluidic devices that should be available in small numbers of pieces at moderate prices. Here, we will present first results of such 3D printed cell culture systems made from plastics and show their use for scaffold based applications.
3D printing of hydrogels in a temperature controlled environment with high spatial resolution
Authors: Fischer Benjamin , Schulz André , Gepp Michael M. , Neubauer Julia , Gentile Luca , Zimmermann Heiko 
Published: December 2016

Abstract
There is great hope in 3D printing techniques to create patient specific scaffolds for therapeutic applications. The majority of these approaches rely on materials that both give support to cells and effectively mimic a tissue specific microenvironment. Hydrogels provide an exceptional support for cells but their physicochemical properties are not suited for conventional additive layer manufacturing. Their low viscosity and resulting fluidic nature inhibit voluminous 3D deposition and lead to crude printing accuracy. To enhance mechanical features, hydrogels are often chemically modified and/or mixed with additives; however it is not clear whether these changes induce effects on cellular behavior or if in vivo applications are at risk. Certainly it increases the complexity of scaffold systems. To circumvent these obstacles, we aimed for a 3D printing technique which is capable of creating scaffolds out of unmodified, pure hydrogels. Here we present a new method to produce alginate scaffolds in a viscosity- independent manner with high spatial resolution. This is achieved by printing in a sub-zero environment which leads to fast freezing of the hydrogels, thus preserving the printed shape and circumventing any viscosity dependent flows. This enables the user to create scaffolds which are able to reflect soft or stiff cell niches.
Biocompatibility of photopolymers for additive manufacturing
Authors: Leonhardt Stefan , Klare Martin , Scheer Maurice , Fischer Theresa , Cordes Burghard , Eblenkamp Markus 
Published: December 2016

Abstract
To establish photopolymers for the production of class II or class III medical products by additive manufacturing it is essential to know which components of photopolymeric systems, consisting of monomers, photoinitiators and additives, are the determining factors on their biocompatible properties. In this study the leachable substances of a cured photopolymeric system were eluted and identified by HPLC-MS detection. In addition the cured photopolymer was testes for cytotoxicity and genotoxicity according to DIN EN ISO 10993 for long time applications. The results showed that uncured residual monomers are the determining factor on the biocompatible properties of the photopolymeric system. Strategies to reduce these residual monomers in the cured photopolymer are presented.
Biochemical piezoresistive sensors based on pH- and glucose-sensitive hydrogels for medical applications
Authors: Schmidt Ulrike , Guenther Margarita , Gerlach Gerald 
Published: December 2016

Abstract
Many conventional analysis techniques to detect chemical or biological species are able to achieve a high detection sensitivity, however, they are equipment- or time-expensive due to a multi-step procedure. In this work we describe sensor concepts using piezoresistive pressure sensor chips with integrated analyte-sensitive hydrogels, that enable inexpensive and robust biochemical sensors which are miniaturizable and in-line capable. Biocompatible hydrogels were developed and tested for pH- and glucose-monitoring during the chemical and biochemical processes. For that, monomer mixtures based on hydroxypropyl methacrylate HPMA, 2-(dimethylamino)ethyl methacrylate DMAEMA, tetraethylene glycol dimethacrylate TEGDMA and ethylene glycol EG were photo-polymerized. By means of carbodiimide chemistry, glucose oxidase was bound to the pH-sensitive HPMA/DMAEMA/TEGDMA/EG hydrogel squares causing the glucose-sensitivity. The crosslinked hydrogels were integrated in piezoresistive pressure sensors of different designs. pH- and glucose-depending reversible gel swelling processes were observed by means of the output voltage of dip sensors and of a novel implantable flexible sensor set-up. Due to its biocompatible components, the latter could be used inside the human body monitoring physiological blood values, for example glucose.
Novel wireless measurement system of pressure dedicated to in vivo studies
Authors: Bances Enrique , Fiestas Antonio , Witte Hartmut 
Published: December 2016

Abstract
This paper reports on the development of a wireless system to monitor the thoracic cavity pressure in mammals. This project seeks to open a new field using the radio frequency (RF) technology in the studies of the interaction between breathing and locomotion in mammals. Furthermore, this study embodies the first step to develop a method of telemetry and remote monitoring based on implantable devices. In addition, it can be modified with other sensors to measure different physiological parameters.
Deep brain stimulation: increasing efficiency by alternative waveforms
Authors: Argiti Katerina , Joseph Kevin , Mottaghi Soheil , Feuerstein Thomas J. , Hofmann Ulrich G. 
Published: December 2016

AbstractDeep brain stimulation (DBS) is based on the effect of high frequency stimulation (HFS) in neuronal tissue. As a therapy option for patients suffering from e.g. Parkinson’s disease, DBS has been used for decades. Despite the widespread use, the effect of HFS on neurons is not fully investigated. Improving the stimulation efficiency und specificity could increase the efficiency of the INS (internal neuronal stimulator) as well as potentially reduce unwanted side effects. The effect of HFS on the GABAergic system was quantified using whole cell patch clamp electrophysiology during HFS stimulation in cortical human brain slicesin vitro. Rectangular, sine, sawtooth and triangular waveforms were applied extracellularly. Since HFS has been hypothesized to increase the activity of the axons of GABAergic interneurons, a decrease in activity can be observed in the pyramidal cells that the interneurons project to. By isolating the incoming non- GABAergic events, we can filter out only the GABAAcurrents which can be verified using a GABAAantagonist. The results show that all the waveforms effectively increase the GABAAcurrents. The triangle waveform causes the highest significant increase in the activity which further increases over time after the stimulation was turned off.
Prediction of immediately occurring microsleep events from brain electric signals
Authors: Golz Martin , Sommer David , Krajewski Jarek 
Published: December 2016

Abstract
This contribution addresses the question if imminent changes of the cortical state are predictable. The analysis is based on 1484 examples of microsleep (MS) and 1940 counterexamples of sustained attention (SA), both observed during overnight driving in the simulator. EEG segments (8 s in length) immediately before each respective event were included. Features were extracted by (i) modified periodogram and (ii) Choi-Williams distribution. Machine learning algorithms, namely the optimized learning vector quantization (OLVQ) and the support-vector machine with Gaussian kernel function (SVM), were trained in order to map signal features to the event type (MS or SA). Cross validation analysis yielded test set classification accuracies of 87.5 ± 0.1 % and 82.7 ± 0.1 % for feature set (i) and (ii), respectively. In general, SVM outperformed OLVQ. In conclusion, EEG contains enough information to predict immediately upcoming microsleep events.
Determining cardiac vagal threshold from short term heart rate complexity
Authors: Hamdan Rami Abou , Schumann Andy , Herbsleb Marco , Schmidt Marcus , Rose Georg , Bär Karl-Jürgen , Gabriel Holger 
Published: December 2016

Abstract
Evaluating individual aerobic exercise capacity is fundamental in sports and exercise medicine but associated with organizational and instrumental effort. Here, we extract an index related to common performance markers, the aerobic and anaerobic thresholds enabling the estimation of exercise capacity from a conventional sports watch supporting beatwise heart rate tracking. Therefore, cardiac vagal threshold (CVT) was determined in 19 male subjects performing an incremental maximum exercise test. CVT varied around the anaerobic threshold AnT with mean deviation of 7.9 ± 17.7 W. A high correspondence of the two thresholds was indicated by Bland-Altman plots with limits of agreement −27.5 W and 43.4 W. Additionally, CVT was strongly correlated AnT (r
p
= 0.86, p < 0.001) and reproduced this marker well (r
c
= 0.81). We conclude, that cardiac vagal threshold derived from compression entropy time course can be useful to assess physical fitness in an uncomplicated way.
Reducing of gradient induced artifacts on the ECG signal during MRI examinations using Wilcoxon filter
Authors: Schmidt Marcus , Krug Johannes W. , Rose Georg 
Published: December 2016

Abstract
The electrocardiogramm (ECG) is the state-of-the-art signal for gating in cardiovascular magnetic resonance imaging and patient monitoring. Using the ECG for gating and monitoring during the magnetic resonance imaging examination is a high challenging task due to the superimposition of the magnetohydrodynamic effect, radio-frequency (RF) pulses and fast switching gradient magnetic fields. The gradient induced artifacts hamper the correct QRS detection which is needed for correct gating and heart rate calculation and ECG displaying for patient monitoring. To suppress the gradient artifacts from the ECG signal acquired during MRI, a technique based on the Wilcoxon filter was developed. It was evaluated using ECG signals of 14 different subjects acquired in a 3 T MRI scanner. It could be shown reliable results for reducing gradient induced artifacts in the ECG signal in real-time.
Automatic detection and mapping of double potentials in intracardiac electrograms
Authors: Oesterlein Tobias , Kramlich Alexander , Lenis Gustavo , Luik Armin , Schmitt Claus , Dössel Olaf 
Published: December 2016

Abstract
Catheter ablation has become a very efficient strategy to terminate sustained cardiac arrhythmias like atrial flutter (AFlut). Identification of the optimal ablation spot, however, often proves difficult when scar from previous ablations is present. Although the application of electro-anatomical mapping systems allows to record thousands of intracardiac electrograms (EGMs) from each atrium, state-of-the-art techniques provide limited options for automatic signal processing. Goal of the presented research was the development of an algorithm to detect EGMs that present double potentials (DPs), as these often indicate functional or anatomical lines of block for cardiac excitation. Using an annotated database, we developed several features based on the morphological descriptors of DPs. These were used to train a binary decision tree which was able to detect DPs with a correct rate of over 90%.
Modeling the pelvic region for non-invasive pelvic intraoperative neuromonitoring
Authors: Moszkowski Tomasz , Krüger Thilo , Kneist Werner , Hoffmann Klaus-Peter 
Published: December 2016

Abstract
Finite element analysis (FEA) of electric current distribution in the pelvis minor may help to assess the usability of non-invasive surface stimulation for continuous pelvic intraoperative neuromonitoring. FEA requires generation of quality volumetric tetrahedral mesh geometry. This study proposes the generation of a suitable mesh based on MRI data. The resulting volumetric mesh models the autonomous nerve structures at risk during total mesorectal excision. The model also contains the bone, cartilage, fat, skin, muscle tissues of the pelvic region, and a set of electrodes for surface stimulation. The model is ready for finite element analysis of the discrete Maxwell’s equations.
Best practice: surgeon driven application in pelvic operations
Authors: Krueger Thilo B. , Wegner Celine , Somerlik-Fuchs Karin H. , Hoffmann Klaus-Peter , Mattmueller Rudi 
Published: December 2016

Abstract
In applied biomedical engineering and medical industry the transfer of established technology towards customers’ needs is essential for successful development and therefore business opportunities. In chronological order, we can show the transfer of scientific results of neurophysiological research into an existing neuromonitoring system and product which can be used by non-experts in medical technology in the operating room environment. All neurophysiology functions were realized in an intuitive graphical user interface. To stimulate the autonomous nerves, a specialized parameter paradigm was used, different from motor nerve stimulation. In the background, a complex signal processing algorithm recorded smooth muscle and bladder manometry data in synchronized time and automatically detected neurophysiological signals. The acquired data was then presented in real-time. With this effort a complex scientific task could be simplified to a Yes/No statement to the end-user. Beside all the reduction of complexity, the scientific challenge was still obtained, as raw-data is still possible to be recorded.
Vasomotor assessment by camera-based photoplethysmography
Authors: Trumpp Alexander , Schell Joachim , Malberg Hagen , Zaunseder Sebastian 
Published: December 2016

Abstract
Camera-based photoplethysmography (cbPPG) is a novel technique that allows the contactless acquisition of cardio-respiratory signals. Previous works on cbPPG most often focused on heart rate extraction. This contribution is directed at the assessment of vasomotor activity by means of cameras. In an experimental study, we show that vasodilation and vasoconstriction both lead to significant changes in cbPPG signals. Our findings underline the potential of cbPPG to monitor vasomotor functions in real-life applications.
Classification of morphologic changes in photoplethysmographic waveforms
Authors: Tigges Timo , Music Zenit , Pielmus Alexandru , Klum Michael , Feldheiser Aarne , Hunsicker Oliver , Orglmeister Reinhold 
Published: December 2016

Abstract
An ever increasing number of research is examining the question to what extent physiological information beyond the blood oxygen saturation could be drawn from the photoplethysmogram. One important approach to elicit that information from the photoplethysmogram is the analysis of its waveform. One prominent example for the value of photoplethysmographic waveform analysis in cardiovascular monitoring that has emerged is hemodynamic compensation assessment in the peri-operative setting or trauma situations, as digital pulse waveform dynamically changes with alterations in vascular tone or pulse wave velocity. In this work, we present an algorithm based on modern machine learning techniques that automatically finds individual digital volume pulses in photoplethysmographic signals and sorts them into one of the pulse classes defined by Dawber et al. We evaluate our approach based on two major datasets – a measurement study that we conducted ourselves as well as data from the PhysioNet MIMIC II database. As the results are satisfying we could demonstrate the capabilities of classification algorithms in the automated assessment of the digital volume pulse waveform measured by photoplethysmographic devices.
Novel computation of pulse transit time from multi-channel PPG signals by wavelet transform
Authors: Pielmuş Alexandru-Gabriel , Pflugradt Maik , Tigges Timo , Klum Michael , Feldheiser Aarne , Hunsicker Oliver , Orglmeister Reinhold 
Published: December 2016

Abstract
Being able to accurately monitor blood pressure in a reliable, truly non-invasive manner is a highly sought after goal within the biomedical community. In this paper we propose and assess a system, methodology and algorithm for unobtrusively obtaining true pulse transit time data from readily accessible peripheral locations, such as the hand, using a highly synchronous body-sensor-network encompassing an electrocardiogram- and dual mode photoplethysmogram sensor node. The results suggest the feasibility of acquiring such data, which strongly correlates with the recorded reference blood pressure, and can therefore be further employed to track changes thereof.
Semi-automated detection of fractional shortening in zebrafish embryo heart videos
Authors: Nasrat Sara , Marcato Daniel , Hirth Sofia , Reischl Markus , Pylatiuk Christian 
Published: December 2016

Abstract
Quantifying cardiac functions in model organisms like embryonic zebrafish is of high importance in small molecule screens for new therapeutic compounds. One relevant cardiac parameter is the fractional shortening (FS). A method for semi-automatic quantification of FS in video recordings of zebrafish embryo hearts is presented. The software provides automated visual information about the end-systolic and end-diastolic stages of the heart by displaying corresponding colored lines into a Motion-mode display. After manually marking the ventricle diameters in frames of end-systolic and end-diastolic stages, the FS is calculated. The software was evaluated by comparing the results of the determination of FS with results obtained from another established method. Correlations of 0.96 < r < 0.99 between the two methods were found indicating that the new software provides comparable results for the determination of the FS.
Blood pressure measurement on the cheek
Authors: Schneider Sarah , Affeld Klaus , Kopic Claudia , Kertzscher Ulrich 
Published: December 2016

Abstract
In a large group of patients, it is impossible to measure blood pressure using an upper arm cuff. An alternative, non-invasive method of blood pressure measurement is required for patients with severe limb deformities or obesity, for amputees, and in the emergency medicine. The device proposed here measures blood pressure in the cheek using a small pressure pad and a pump to occlude the cheek artery – arteria facialis – and assesses blood flow with an infrared light source and a detector. The infrared light signal is analysed to assess the systolic and diastolic blood pressure of the patient. Manual evaluation of the light intensity signal showed a good agreement between cheek blood pressure measurement and a reference measurement using an upper arm cuff.