bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of accuracy and glycemic control of FGM and CGM and impact on mental well-being
Authors: Gesslbauer Manuel , Koehler Gerd , Baumgartner Christian , Lozanović Šajić Jasmina
Published: September 2022

The incidence of diabetes is increasing globally. Short and long-term effects of diabetes can negatively affect the lives of a person and their relatives. A good glycaemic control is important. Compared to conventional blood glucose measurement with capillary blood, which is obtained by finger pricking, it is now possible to continuously measure glucose using sensors that are placed in the subcutaneous tissue and remain there for several days to weeks. This means that the "tissue sugar" and not the blood sugar directly is determined. For this reason, it is important to determine the accuracy of these sensors. Furthermore, such systems can influence not only the physical but also the psychological/mental health of people with diabetes and their relatives. Reimbursement of sensors differs in Europe. This overview is based on the Austrian health care system.
Impact of the fiber cutting angle on fiber optic proximity sensors in endoscopy
Authors: Giacoppo Giuliano A. , Schunter Lena , Pott Peter P.
Published: September 2022

In current endoscopes, the estimation of the proximity to the surrounding tissue is based on the experience of the user. To provide precise proximity meassurement, a suitable sensor is needed. This paper presents a fiber optic proximity sensor that is inserted through the working channel of an endoscope. The impact of the fiber cutting angle at the distal end of the optical fiber is investigated. If the fiber is cut at a 3° angle to the optical axis, the measurement signal in axial direction can be increased by 126mV at the peak (measurement accuray 4.9 mV). A 45° fiber cutting angle allows radial measurement but with a weak measurement signal compared to an axial measurement. A distance between endoscope tip and intestine wall up to 15 mm can be measured. In conclusion, optical fibers can be used to insert a low-cost sensor through a working channel of an endoscope. By modifying the fiber cutting angle, an increased sensor signal can be obtained in the axial direction and a measurement in radial direction is possible.
Blood Pressure Estimation based on Electrocardiograms
Authors: Wuerich Carolin , Wichum Felix , El-Kadri Omar , Ghantawi Kusay , Grewal Navraj , Wiede Christian , Seidl Karsten
Published: September 2022

To overcome limitations of currently used blood pressure measurement devices in accuracy, continuity and comfort, we propose an approach for blood pressure estimation from electrocardiogram (ECG) signals only. Thereby, statistical signal features are extracted from the ECG which, eventually, serve as input to a random forest regression. The method is trained and tested on MIMIC III waveform data with a large range of blood pressure values. It obtains a mean absolute error ± standard deviation of 3.73 ± 5.19 mmHg for diastolic blood pressure (DBP) and 5.92 ± 7.23 mmHg for systolic blood pressure (SBP), with Pearson coefficients ΥDBP=0.92 and ΥSBP=0.91 respectively.
Fragmentation thresholds simulated for antibubbles with various infinitesimal elastic shells
Authors: Anderton Nicole , Postema Michiel
Published: September 2022

Antibubbles are small gas bubbles comprising one or multiple liquid or solid cores, typically surrounded by stabilising shells. Acoustically active microscopic antibubbles have been proposed for use as theranostic agents. For clinical applications such as ultrasound-guided drug delivery and flash-echo, it is relevant to know the fragmentation threshold of antibubbles and the influence of the stabilising shells thereon. For antibubbles with an infinitesimal frictionless elastic shell of constant surface tension, we simulated ultrasoundassisted fragmentation by computing radial pulsation as a function of time using an adapted Rayleigh-Plesset equation, and converting the solutions to time-variant kinetic energy of the shell and time-variant surface energy deficit. By repetition over a range of pressure amplitudes, fragmentation thresholds were found for antibubbles of varying size, core volume, shell stiffness, and driving frequency. As backscattering increases with scatterer size, and as drug delivery would require vehicles just small enough to pass through capillaries with a relatively large payload, we chose to present typical results for antibubbles of resting diameter 6 μm with a 90% incompressible core. At a driving frequency of 13 MHz, the fragmentation threshold was found to correspond to a mechanical indices less than 0.4, irrespective of shell stiffness. This mechanical index is not considered unsafe in diagnosis. That means that antibubbles acting as drug-carrying vehicles could release their payload under diagnostic conditions.
Temperature-induced modulation of the electrophysiological behavior of A549 lung cancer cells
Authors: Langthaler Sonja , Rienmüller Theresa , Lozanović Šajić Jasmina , Baumgartner Christian
Published: September 2022

Cancer cells typically exhibit altered ion channel expression and membrane potential, wich plays an important role in various processes such as proliferation or apoptosis Hence, therapeutic strategies that modulate ion channel activity or shift the membrane potential prove to be promising for cancer therapy. Since temperature significantly affects ion channel function, deviation from normal body temperture might provide akey factor in electrophysiological progression. In this pilot study, we focused on a first insight into the temperature-induced modulation of A549 cells using an automated patch clamp system. Measurements of 14 cells at hypo-, normo- and hypertermia were accomplished to investigate the temperature-dependent electophysiological behavior. The results revealed that both, temperatures below and above normal body temperature affect the current and potential of A549 cells. In hyperthermia the potential tends to more hyperpolarized values, while conversely, in hypothermic conditions we observer mainly a lower current reponse and thus a depolarization of the membrane potential.
Experimental setup for the ultrasonic fractionation of flowing whole blood in a capillary
Authors: Smalberger Charl , Nathan Malavika , Rubin David M. , Nel Marietha , Kotopoulis Spiros , Carlson Craig S. , Postema Michiel
Published: September 2022

If a long ultrasound driving pulse is chosen such, that its frequency is greater than the resonance frequency of one cell type and less than the resonance frequency of another cell type, the cells are separated in different nodes and antinodes of the standing sound field. The purpose of this study was to build an experimental setup for the ultrasonic fractionation of whole blood in flow conditions. Blood fractionation is the separation of whole blood into its separate components, commonly used for analysis and transfusions. The experimental setup comprised a container with singleelement ultrasound transducers customisable in elevation and azimuth, focussed on a capillary through which blood was flowing. The acoustic focus coincided with the optical focus of a microscopic system to which a high-speed camera was attached. Ultrasound transducers were used with centre frequencies between 1MHz and 20MHz and with pressure amplitudes less than 1MPa. The duty cycle was greater than 10% in all experiments. The field of view was 0.2×0.2mm2. The optical resolution and camera speed allowed for visibility of red and white blood cells during flow conditions. Preliminary results show that red and white blood cells could be forced to move in opposite directions. The acoustic frequencies and pressures used were representative for those used in clinical diagnosis. We have shown that ultrasonic whole blood fractionation is feasible using ultrasound. Sonic fractionation speed might be an indicator for diseases such as malaria.
A new method for OCT Imaging of the Eustachian tube
Authors: Boese Axel , Fritzsche Holger , Paasche Gerrit , Lenarz Thomas , Schuon Robert
Published: September 2022

For treatment decision of Eustachian tube (ET) dysfunction, a reliable diagnosis of the reason for this dysfunction is of interest. Imaging methods like CT or MRI do not show enough details today. Endoscopy is challenging but can show at least superficial structures at the pharyngeal orifice. To look into the deeper tissue layers vascular imaging methods like IVUS and OCT were evaluated already. But these procedures are not made and certified for this application and come with risks for the patient. To overcome this issue, we propose the use of an additional closed end guide catheter that can be advanced into the ET. An OCT catheter can be placed inside without touching the patient’s tissue. In this paper we evaluate this approach on a sheep cadaver head and a human cadaver head.
Proof-of-Concept Study for Reflectance Pulse Oximetry Using Optical-Fibre-Based Sensors
Authors: Annaheim Simon , Braun Fabian , Bernhard Leah , Pfammatter Amarin , Proença Martin , Bonnier Guillaume , Ferrario Damien , Lemay Mathieu , Rossi René M.
Published: September 2022

Optical fibres enable to design of new textile-based sensors for an unobtrusive, continuous, and long-term acquisition of photoplethysmography (PPG) signals. However, no research has been done about the accuracy of measuring blood oxygen saturation (SpO2) and the feasibility of PPG-based blood pressure measurement. This proof-ofconcept study examined these aspects for a woven sensing patch applied on the forehead in five healthy participants. During a controlled desaturation study, SpO2 estimation revealed an amplitude of the root-mean-squared error (ARMS) of 3.6%, and acceptable signal quality for blood pressure estimation was achieved for 40% of all data. These results indicate that textile-based sensors can reach the required PPG signal quality to simultaneously estimate multiple vital signs, including blood pressure.
Digital Light Processing of Round Window Niche Implant Prototypes for Implantation Studies
Authors: Mau Robert , Nazir Jamal , Gao Ziwen , Alcacer Labrador Dorian , Repp Felix , John Samuel , Lenarz Thomas , Scheper Verena , Seitz Hermann , Matin-Mann Farnaz
Published: September 2022

A new approach that offers the potential for local drug delivery to the inner ear is a 3D printed, patient individualized, drug-loaded implant that precisely fits into the round window niche (RWN). Anatomically correct digital light processing (DLP) 3D printed implant prototypes are beneficial for preoperative planning and rehearsal of implantation techniques due to tactile feedback. The aim is to define desired mechanical material properties for future RWN implants. For this purpose, RWN implant prototypes (RWN-IPs) were DLP 3D printed using commercially available E-Shell 500 and E-Shell 600 materials (Envisiontec GmbH, Gladbeck, Germany) and a selfestablished PEGDA700 composition. These photopolymers are suitable for 3D printing RWN-IPs that feature different mechanical characteristics. The (1) mechanical properties (tensile test) were investigated, (2) the implantation feasibility and (3) fitting accuracy in human cadaver RWN were evaluated. As a result, E-Shell 500 has relatively high stretchability (ɛm ~ 60%) while E-Shell 600 and PEGDA700 are brittle and PEGDA700 has low strength. The E-Shell 500 material performs by far the best at handling and insertion. EShell 600 has adequate strength but is hard to handle because of rigid material behavior. PEGDA700 enables high 3D printing accuracy but lacks adequate mechanical behavior for adequate insertion of implant prototypes in RWN.
Criteria for Implant Fit Assessment in Total Knee Arthroplasty – A Review
Authors: Grothues Sonja , Radermacher Klaus
Published: September 2022

Patient satisfaction in total knee arthroplasty is still limited and lower compared to patient satisfaction in total hip arthroplasty. While there are multiple influence factors for patient satisfaction, implant design is one aspect to consider. In clinical practice, the patient-specific assessment of implant fit is limited to a matching of the anteroposterior and mediolateral size, based on X-rays. Hence, the goal of this review was to identify other potential criteria for a patientspecific implant fit evaluation. A literature review was performed in PubMed. Inclusion criteria were a patientspecific assessment of knee implant components, a comprehensible motivation or a statistically proven relationship with an outcome measure, and a clear method description. Implant fit was considered not only as a matching of size, shape and interface, but also to include the implant’s (rotational) alignment, as proposed by Dai et al. (2014). Several studies reported a statistically significant relationship of implant fit criteria with outcome measures. Many more studies proposed fit criteria, motivated by a potential relationship with outcome measures. Most criteria assessed the bone-implant interface, second the morphology of the articulating surfaces and third the component and resulting bony alignment. Obstacles for the assessment of the criteria identified is the limited availability of 3D surface models in TKA. However, with new imaging technologies this availability is likely to increase. The decision process regarding the implant in TKA could be supported by a comprehensive automated fit analysis of several designs and/or sizes. An adequate matching of the implant to the respective patient may improve patient satisfaction.
Towards Test Bench for Aspiration Catheters in Realistic Evaluation Scenarios
Authors: Paulsen Benjamin Alexander , Schwenke Hannes , Seemann Jakob , Schramm Peter , Männel Georg , Rostalski Philipp
Published: September 2022

Aspiration catheters play an important role in mechanical thrombectomy in interventional neuroradiology as they provide support for stent retrievers or are increasingly used separately for contact aspiration. To evaluate the performance of different aspiration catheters in terms of suction force, most current studies rely on manual measurement methods or the suction force is not measured close to the aspiration catheter tip. Moreover, there is currently no standardized method that records measurements digitally and with high temporal resolution. To overcome these challenges, we propose a new test bench that simulates a dedicated aspiration scenario and takes measurements close to the aspiration catheter tip. To meet the requirements, a simplified vascular phantom, a pressure sensor and a simplified clot model were implemented in the prototype. To demonstrate the applicability of the prototype, two commonly used aspiration catheters were evaluated. The obtained measurements show that it is possible to perform standardized comparisons between aspiration catheters from different manufacturers as well as different aspiration pumps and aspiration tubings and their combinations. The developed prototype overcomes the still widely used manual and semimanual and thus error prone measurement methods for the evaluation of vacuum based thrombectomy systems.
Muscle fatigue detection using near-infrared spectroscopy and electromyography
Authors: Badoni Abhinav , Agarwal Kshitij , Pinkoski Adam , Samant Rahul , DeLorey Darren , Vette Albert
Published: September 2022

Introduction: Muscle fatigue is often experienced by athletes and in work settings. Excessive fatigue can lead to injury and musculoskeletal disorders. Surface electromyography (EMG) is typically used to detect and ultimately prevent fatigue during isometric movement. The application of EMG to fatigue detection in dynamic movement requires, however, a secondary confirmation of fatigue based on physiological measures. Our objective was to determine if muscle oxygenation derived via near-infrared spectroscopy (NIRS) was correlated with relevant EMG indicators of neuromuscular fatigue and whether observed correlations were related to the fatigue process. Methods: Bilateral electromyograms from three upper leg muscles and the tissue oxygenation index (TOI) of the vastus lateralis muscle were recorded in sixteen non-disabled individuals during cycle ergometry to volitional exhaustion. Six EMG activity features were extracted and the Pearson correlation coefficient between each feature and TOI was determined. Results: The EMG root mean square, spectral standard deviation, second spectral moment, and zero-crossing rate (ZC) were strongly correlated with TOI. The time course of ZC and the correlation of this feature with TOI suggest that there could be a relation between muscle oxygenation and fatigue. Conclusion: Future work should use the knowledge gained in this study to investigate whether NIRS can be used to verify the onset of fatigue as detected by EMG.
Augmented Reality for 6-DoF Motion Recording, Preview, and Execution to Enable Intuitive Surgical Robot Control
Authors: Karnam Murali , Zelechowski Marek , Cattin Philippe C. , Rauter Georg , Gerig Nicolas
Published: September 2022

In robot-assisted surgeries, the surgeon focuses on the surgical tool and its pose, and not on the complete robot’s shape. However, the joints of redundant robots (robots that have more degrees of freedom (DoF) than needed for the positioning of surgical tools) might move in unexpected/undesired ways. Joint motions that lead to patient or collisions are safety critical. We assume that the medical personnel in the operating room can best decide if a planned robot motions come too close to the patient or not. Therefore, we propose an augmented reality-based solution to interact with the robot during surgery planning, and intervention. The tool can be used to command a robot by drawing a trajectory in augmented reality (AR), visualizing the robot movement to check if it is safe before execution. The proposed solution allows surgeons to plan safe robot motion paths before-hand and adapt them when necessary in situ. As a proof-of-concept, we implemented and demonstrated the proposed solution on a 7-DoF redundant robot by commanding different trajectories. The control architecture to plan and execute motion for a surgical robot using AR is a key result of this work.
LA-TT-EALR / PromCERA: Comparison of preoperatively performed electrically evoked auditory potentials at the brainstem and cortical level during local anesthesia
Authors: Polterauer Daniel , Mandruzzato Giacomo , Neuling Maike , Polak Marek , Müller Joachim , Hempel John-Martin
Published: September 2022

Introduction: In the past years, some groups established methods to use promontory stimulation and subjective responses as a tool for preoperative stimulation of the cochlea before cochlear implant (CI) surgery by a temporary transtympanic needle placed on the middle ear. Our research group tested CI candidates when the presence of the auditory nerve could not be confirmed by other pre-operative tests and analyzed objective results of electrical auditory brainstem response recorded with trans-tympanic promontory stimulation in local anesthesia (LA-TT-EABR) with a “golfclub” electrode placed on the round window niche (Polterauer et al. 2018). However, EABR recording suffers from an electrical artifact from the stimulation and focuses on the excitability of the solely auditory nerve. We hypothesize that late evoked potential response (EALR) can be used for the assessment of the auditory pathway up to the cortical area with less electrical artifact interference. Methods: The trans-tympanic electrically evoked auditory late response in local anesthesia (LA-TT-EALR) was added to our protocol right after the LA-TT-EABR in a unique recording session. In this study, we investigated the feasibility of LA-TT-EALR using MED-EL hardware and software. These two pre-operative trans-tympanic measurements, LATT- EABR and LA-TT-EALR, were compared. Results: In a total n=18 tested subjects, it could be possible to record LA-TT-EABR in 10 and LA-TT-EALR in 13. In contrast to the fact that acoustically evoked auditory late responses are often hard to detect, and an electrical artifact heavily affects LA-TT-EABR, we did not experience these problems on LA-TT-EALR recordings. The matching between two measurements was present in 67% of the cases. Conclusion: LA-TT-EALR may be a complement to the existing state-of-the-art LA-TT-EABR for pre-operative assessment before cochlear implantation offering information about auditory pathways in the auditory brainstem and cortex with a small increase of recording time. The equivalency of these two methods is encouraging.
360° Laparoscopic Imaging System to Facilitate Camera Control and Orientation in Minimally Invasive Surgery
Authors: Schäfer Max B. , Eggstein Selina , Stewart Kent W. , Pott Peter P.
Published: September 2022

During laparoscopic procedures, the surgeon's view of the situs, and thus her or his performance, is dependent on the skills of the camera assistant. The surgeon lacks control over his own field of view and there is a high potential for reducing mental load and workflow issues. In this paper, a research setup of a 360° laparoscopic imaging system is presented and evaluated. The system consists of a 360° camera and a head-mounted display, through which the surgeon can inspect the situs. In a user test, the system showed advantages over a conventional laparoscope regarding orientation in the situs, intuitiveness of operation, and faster task completion.
Investigation of an Acceleration Pipeline for Single Fiber Action Potential Simulation
Authors: Oltmann Andra , Petersen Eike , Kusche Roman , Rostalski Philipp
Published: September 2022

Surface electromyography (sEMG) records the electrical potentials on the skin surface generated by the electrical activity of muscle fibers. To better understand physiology and to assess signal processing algorithms, sEMG models have been developed in the past. However, numerical models required for modeling accurate geometries very often have a high computational complexity rendering realistic simulations challenging. In order to cope with this challenge, a pipeline is investigated to accelerate the calculation of the single fiber action potential (SFAP) based on the principle of reciprocity. To enable a comparison to an analytical solution, the investigation is carried out in a highly simplified muscle model. The results show that the pipeline is suitable for calculating SFAP with a low mean absolute error sufficient for application in sEMG models. In addition, there is a significant reduction of the calculation time allowing the simulation of even highly complex geometries and a large number of muscle fibers.
Feedback Linearization of a Blower in an Anesthesia Workstation
Authors: Prüßmann Jannik , Männel Georg , Brendle Christian , Rostalski Philipp
Published: September 2022

Radial compressors, Blowers, which are often used in modern devices for medical ventilation, are known to have non-linear dynamics regarding the generated pressure. To make them accessible for the large field of linear control theory their model needs to be linearized. This paper uses a gray box model of a blower driven by a brushless direct current (BLDC) motor to design a controller based on feedback linearization. The controller is designed to achieve approximate linear closed loop behavior of the system. The controller is then evaluated concerning reference tracking and disturbance rejection in simulation and on a demonstrator system. The evaluation showed that an approximate linear closed loop behavior was achieved.
Prediction of Fluorescent Ki67 Staining in 3D Tumor Spheroids
Authors: Bruch Roman , Vitacolonna Mario , Rudolf Rüdiger , Reischl Markus
Published: September 2022

3D cell culture models are important tools for the development and testing of new therapeutics. In combination with immunoassays and 3D confocal microscopy, crucial information like morphological or metabolic changes can be examined during drug testing. However, a common limitation of immunostainings is the number of dyes that can be imaged simultaneously, as overlaps in the spectral profiles of the different dyes may result in cross talk. We therefore present a 3D deep learning method, able to predict fluorescent stainings of specific antigens on the basis of a nuclei staining. Using the proliferation marker Ki67, we showed that the presented model was able to predict the Ki67 staining with a strong correlation to the real signal. Additional analysis showed, that the model was not relying on signal cross talk. This approach, based on staining of the cell nuclei and subsequent prediction of the target antigen, could reduce the number of parallel antigen stains to a minimum and incompatible staining panels could be circumvented in the future.
Automatic detection of subviral particles in fluorescence microscopy images of Marburg virus infected cells using a convolutional neural network
Authors: Naber Sarah , Busch Nils , Rausch Andreas , Schanze Thomas
Published: September 2022

In collaboration with the Institute of Virology at the University of Marburg, a tracking algorithm has been developed in recent years. Thereby, for the tracking of subviral particles and their intracellular transport through the cell, the detection of these particles is the first major step. In this work a deep-learning based approach for automatic processing of fluorescence video sequences of virus infected cells is presented. The focus of this work was to generate synthetic data for training neuronal networks and to represent a particle using only a single delta peak. It was shown that a simple convolutional network is able to predict the particle positions with an almost identical accuracy as the algorithm developed by Kienzle, Rausch and colleagues [1-3], and that even a small dataset is sufficient for that purpose.
Analysis of Dielectric Properties of Gelatin-based Tissue Phantoms
Authors: Hess Andreas , Liu Jan , Pott Peter P.
Published: September 2022

In this work, an electrode was developed to determine the dielectric properties of tissue phantoms using impedance measurements. For this purpose, a coaxial electrode design was selected as the most suitable electrode design. Three tissue phantoms (blood, fat, muscle) were prepared from distilled water, sodium chloride, 1,2-propanediol, agar, and gelatine, and then characterized. Measurements were performed using an impedance analyzer in a range between 1 kHz and 1 MHz. A comparison with literature values showed good correspondance of the permittivity values determined, thus proving the applicability of the electrode design. However, the conductivity values measured were different from literature values. In the future, alteration and minimization of the electrode can be done to further improve the characterization.
KneTex – Improvements to classification methods for a sensor system for rehabilitation after ACL surgery
Authors: Cramer Lukas , Yavuz Sinan , Schlage Nana , Mühlen Andreas , Kitzig Andreas , Naroska Edwin , Stockmanns Gudrun
Published: September 2022

Injuries and the associated surgery to the anterior cruciate ligament (ACL) can often trigger unpredictable effects, such as the so-called giving way effect, which is an uncontrolled buckling of the knee joint. For this purpose, the KneTex project has developed a smart textile-integrated sensor and actuator bandage system to record the movement of such patients and to monitor and support the rehabilitation process. Long-term monitoring and analysis of the movement data will identify patterns or gait types that can lead to a giving way effect. This paper describes the recent developments of the random forest model-based motion classification system developed within the project. Improvements have been achieved by reducing the number of features needed by 25% using feature importance analysis, speeding up the computation time by 14%, and increasing the classification efficiency. Feature elimination is a useful tool to improve classification systems in settings where feature count is high and feature importance analysis contributed by improving our understanding which sensor of our system are important for the motion classification task.
Automated human temporal-bone experiments
Authors: Kempa Stepan , Martin Michael , Dalhoff Ernst
Published: September 2022

Temporal-bone (TB) experiments are useful for the investigation of middle-ear and inner-ear transfer properties, and the analysis and development of active or passive middleear prostheses or related devices. To acquire the mechanical middle-ear (ME) response, the Laser-Doppler vibrometry (LDV) is utilized as a preferred method. In most setups, the exact measurement point chosen on the biological structure of interest as well as the direction of the corresponding vibration measurement is not precisely defined and of unknown reproducibility. Hence, an automated setup controlling coordinates of TB and measurement direction is developed and tested. To test the reproducibility, TBs were measured with ER7C and ER10C probe microphones employing a small industrial robot to position the TB to the ME points of interest and align it to the laser beam. The position and vibration data acquired at the same locations at different points of time were processed and compared. Measured transfer functions indicate noticeable differences at some frequency ranges. Nonetheless, the reproducibility of positioning to repeatedly measured points proved itself relatively accurate, if no manipulations in the setup are made. In conclusion, the current study shows that automated LDV TB measurement system is in principle capable to adapt to the changes in setup during intermediate preparation steps. With more acquired data, the setup stability and reproducibility can be more precisely verified, and additional improvements can be made.
Camera-based Pain Assessment during Surgical Interventions
Authors: Reichard Bianca , Schrumpf Fabian , Anders Franz , Bode Kerstin , Fuchs Mirco
Published: September 2022

Pain assessment in clinical settings can be a challenging task for clinic staff and patients. An automatic and contactless pain estimation system via facial expression is a decisive advantage. In the following article we present a method for pain classification based on mimic descriptors. To automatically process facial expressions from video data we applied the Facial Action Coding System (FACS). First, we employed a logistic regression model to predict pain using a publicly available database. Second, we utilized this procedure to predict pain in individual intraprocedural patient data. We reached a mean accuracy of 80.94% for the publicly available data and 73.14% for our individual patient data by classifying data as pain and non-pain.
Apnea detection from photoplethysmography signal using dicrotic notch
Authors: Rafl-Huttova Veronika , Cizek Dominik , Rafl Jakub , Rozanek Martin
Published: September 2022

Photoplethysmography signal (PPG) provides information about the cardiovascular, respiratory, or nervous system activity. Recent studies proposed methods of apnea identification from PPG using amplitude or baseline modulation, or area under the curve. We hypothesized that analysis of the dicrotic notch could improve the sensitivity and specificity of apnea detection. We applied four methods to detect apnea from PPG records experimentally obtained from 10 volunteers, where each volunteer simulated three apneic pauses. We adopted the Area under the PPG and Pulse wave amplitude parameters, and we proposed the Dicrotic notch area parameter. For the methods, we determined the delay in apnea detection and the sensitivity and specificity of apnea detection. The average delay in detecting an apneic pause from the PPG using the Dicrotic notch area was 6.1 s. Combining the parameters of the Area under the PPG with the Dicrotic notch area increased the specificity of apnea detection from 73.8% to 80.0%, although sensitivity decreased from 91.1% to 85.6%. The newly proposed parameter Dicrotic notch area showed its potential for automatic apnea detection.
Long Term Evaluation of the Barrier Properties of Polymer/Metal Oxide Hybrid Layers for Use in Medical Implants
Authors: Simon Nicolai , Schmid Marvin , Blendinger Felix , Bucher Volker
Published: September 2022

Encapsulation is essential for mechanically flexible and electrically active implants as it protects them from the harsh environment inside the body. Since the performance and longevity of implants depends on the quality of encapsulation, research continues into new and better encapsulation strategies. Chemical vapour deposition can be used to deposit Parylene-C, a biocompatible polymer, at room temperature. Plasma enhanced atomic layer deposition can be used to deposit ultra-thin, conformal, and hermetic metal oxide layers. These strategies are both used for the encapsulation of implants. In this work, these two methods are combined to create a polymer/metal oxide hybrid system in which a layer system of metal oxides is sandwiched between two Parylene- C layers. DC leakage-current measurement and elevated temperature are used to qualify the barrier property of the layer-system. After more than one year, the barrier properties still show no significant decrease.
A Concept for 6D Motion Sensing with Magnetoelectric Sensors
Authors: Hoffmann Johannes , Hansen Clint , Maetzler Walter , Schmidt Gerhard
Published: September 2022

Active magnetic motion sensing relies on a combination of magnetic sensors and actuators to indirectly sense a time-varying change in position and orientation. Based on our previous work on a 1D setup with magnetoelectric (ME) sensors, we introduce a concept for a full 6D sensing system, which is positioned as a modular setup for human movement pattern capture with regard to neurodegenerative diseases. In this paper, we implemented an inverse model based on ideal triaxial sensors and coils. We then included results from the previous experiments to estimate the prospective performance in a physical setup. We obtained a spatial error of a few cm and approx. 10° with focus on superimposed sinusoidal movements of 1, 5, and 10 Hz.
A systematic review of recorded technical settings used in bipolar and monopolar transurethral resection of bladder tumors
Authors: Kiefer Ann-Kathrin , Espig Kevin , Moeller Knut
Published: September 2022

High-frequency (HF) surgery has been established in medicine for decades and is very popular in transurethral (minimally invasive) surgery. However, the technical settings of generators are almost exclusively based on empirical data. So far, making a well-founded statement about a possible impact of technical parameters in HF surgery is nearly impossible. Therefore, the aim of this research was to systematically review the published data for transurethral resection of bladder tumor (TURBT) to find out, whether the publications consider both sufficiently, technical parameters and physical parameters. It is shown that although technical parameters are reported, they have been insufficiently considered in analyses so far. Further analyses must be performed.
Smartphone based Monitoring of Pediatric Craniofacial Deformities
Authors: Fischer Patrick , Wattendorf Sonja , Hossein Tabatabaei Seyed Amir , Wilbrand Martina , Wilbrand Jan-Falco , Sohrabi Keywan
Published: September 2022

Craniofacial deformities such as positional skull deformities are widespread in infants. The early detection of these deformities is crucial for the effective treatment and the associated minimization or prevention of visual and pathological abnormalities. This paper presents a solution for the early detection of craniofacial deformities using easy available materials in both the domestic and clinical environments. For this purpose, suitable web technologies as well as webserver systems are used in the context of app and server development. Users can use the app to take a bird's eye view of the child's head and use a 50ct coin as scale to then automatically obtain calculated clinical parameters which they can compare with clinical standard values to rule in or out a skull deformity. The concept represents a way to compensate for the lack of specialists in craniofacial surgery as well as knowledge gaps and to digitize care concepts in the healthcare system.
Consideration of the generated network utilization of the IEEE 11073 SDC standard
Authors: Thürk Gregor , Lott Christian , Neumuth Thomas , Rockstroh Max
Published: September 2022

This paper investigates the extent to which the IEEE 11073 SDC standard family loads a communication network. An SDC provider/consumer based on the SDCLib/J from SurgiTAIX AG was implemented as a test environment and several different test scenarios were run in order to gather data sets for different use cases. The analysis of the thus acquired measurements shows a linear, predictable growth in network utilization for almost all combinations of active metrics and value update rates. In the case of very high metric update rates, a stagnation of network utilization can be observed. This behaviour can be explained by the use’s implementation and an unfavourable test setup. Overall, the network load generated by SDC is justifiable.
Modelling of a Positive End-Expiratory Pressure Valve with a Voice-coil Actuator
Authors: Brütt Robin , Männel Georg , Brendle Christian , Rostalski Philipp
Published: September 2022

The positive end-expiratory pressure (PEEP) valve is important in the regulation of the pressure at the patient airways in devices for mechanical ventilation. The goal of this work is to derive a model that sufficiently captures the dynamics of the PEEP valve to be used for model-based control design. This paper describes the development of a model for common PEEP valve designs, thus allowing an adoption for different devices. A simplified first principle model with one mechanical degree of freedom is derived, under the assumption that the valve’s membrane behaves similar to a massspring- damper system. Following a grey-box model approach, physical parameters were lumped together and experimentally determined or identified from acquired data. Therefore, a valve test bench was developed to record various series of measurements. It was possible to determine a suitable flow factor which describes the correlation between flow, valve opening and upstream pressure. Additionally, a damping coefficient was estimated, with which the model achieves a good fit to the measured data at low dynamics and flows.
Introducing micro physiological systems to evaluate new radiopharmaceuticals: A binding study with radiolabeled cetuximab
Authors: Sihver Wiebke , Nitt-Weber Anne-Kathrin , Behrens Stephan , Ullrich Martin , Pietzsch Hans-Jürgen , Namazian Jam Negin , Schmieder Florian , Sonntag Frank
Published: September 2022

Radiopharmaceuticals can be used for targetspecific functional diagnostics, such as PET or SPECT imaging, or radionuclide therapy of diseased tissue, depending on the incorporated radionuclide. Following initial in vitro testing, radiopharmaceutical candidates are usually further characterized in small animals. Since reduction, replacement and refinement (3R) of animal testing is a central precept in preclinical research it would be beneficial to replace at least some of these tests by alternative methods. Using micro physiological system technology, various organ-on-chip models can be created with human cell systems/organoids, which are operated in a circulatory system under defined physiological conditions. Here we present first attempts to introduce micro physiological systems for evaluating radiopharmaceuticals using the radiolabeled anti-EGFR antibody cetuximab as reference compound. In a micro physiological system equipped with six 96-well plate-like microwells in a flow chamber, binding of 64Cu and 68Ga-labeled cetuximab to cells and spheroids grown from A431 (EGFR-positive) and MDA-MB435S (EGFR-negative) cells was measured and compared to conventional microplates. Specific saturation binding of radiolabeled cetuximab at increasing concentrations was analyzed using a phosphor imaging system. The affinity of radiolabeled cetuximab towards A431 spheroids measured in the micro physiological system was in the same range as that of the spheroids in conventional microplates. Within the assays in micro physiological systems, the results showed a trend towards increased affinity for A431 monolayers compared to the spheroids. The values of binding capacity for radiolabeled cetuximab on 2D and 3D A431 cell culture models were in the same order of magnitude when measured in micro physiological systems or in microplates. Building on these first promising results, the work will continue on MPS modules containing advanced human spheroid/ organoid models.
Home Monitoring of the Carotid Arteries Using a Mobile Auscultation Device with App
Authors: Müller Inga , Henze Jasmin , Burmann Anja , Salvi Rutuja , Friebe Michael , Baum Rainer
Published: September 2022

Cerebrovascular diseases like atherosclerosis pose a great threat to health and wellbeing of people worldwide. To enable early diagnosis and treatment of a gradually progressing occlusion of the carotid arteries, we propose the BODYTUNE system. Consisting of a custom-built auscultation device and a mobile application, it aims at enabling the monitoring of the blood flow within the carotid arteries on a regular basis at home. In this work, we present the results of a survey with 65 participants from the system target group to investigate aspects like technical affinity and experience with comparable systems. These results provide the basis on how the BODYTUNE system should be designed to be user-centered, concerns.
Surface analysis of different O2-activated polyurethane-co-silicones using XPS
Authors: Lange Helge , Eickner Thomas , Grabow Niels , Wulf Katharina
Published: September 2022

Polycarbonate-urethane-co-silicone (PCU-Sil) are gaining increasing interest in biomedical application, such as drug delivery systems, coatings and combination products, due to their adjustable mechanical properties. They can be easily processed using a wide range of methods. Biocompatibility can be improved by surface modifications, such as coupling drugs, proteins, antibodies or polymer layers, which extends the range of biomedical applications. To generate additional coupling, the first step would be the generation of functional groups on the polymer surface using surface activations, such as plasma activation. In this context, the assignment of the functional groups is important, which can be done by XPS measurements. Within this study the analysis of the generated functional groups after oxygen (O2) plasma activation of two PCU-Sils was performed. In addition, the stability of the generated surface modification was evaluated after 24 hours. It was surprising that the generated groups were differently stable and also different groups were generated or rearranged over time, which would not have been recognizable if only contact angle measurements were used.
Magnetic extraction of calcium oxalate crystals with iron oxide nanoparticles
Authors: Schwaminger Sebastian P. , Werner Helen , Wengler Michael , Srinivasan Shyam
Published: September 2022

Residual fragments can remain after kidney stone extraction which may necessitate another intervention. Magnetic nanoparticles (MNP) can be applied due to their properties of being able to bind to residual fragments and to be extracted by an external magnetic field. Calcium oxalate crystals and magnetic nanoparticles have been synthesized, characterized and used for binding and magnetic separation studies. The separation is validated by simulation and experimentally. MNP bind covalently to the fractals and a magnetic extraction of calcium oxalate fractals is possible. The agglomeration of MNP can be induced with the addition of salt which improves the extraction process. This proof-of-concept study is the fundament for a new way of stone extraction and can pave the way for new procedures in urology.
Microscale Sensor Fabrication on Curved Needle Surfaces
Authors: Liu Jan , Bajraktari Flakë , Atmaca Ömer , Ly Toni J. , Pott Peter P.
Published: September 2022

Sensor-integrated needles with impedance or other electrochemical sensors have gained increased attention in research. Their potential use is widespread and covers applications such as early disease diagnostics or needle guidance for needle-based interventions. However, fabrication and sensor integration are crucial parts of realizing functionalized needles. In this paper, a review of existing research on microscale sensor arrays on curved needle surfaces is presented. It focusses on medical needles excluding needle-type sensors. Especially, means of fabrications including flexible thin-film-based sensors or photolithography are discussed. Although they provide satisfactory results, no manufacturing method is yet ready for bulk production.
Full-field electroretinography examinations of the human eye with the eye diagnostic device PEP-2000 – First results
Authors: Schieding Nikola , Reuter Thomas , Grundmann Andreas , Walther Sebastian , Klee Sascha
Published: September 2022

Full-field electroretinography (full-field ERG) forms the diagnostic basis for numerous pathologies of the eye. For this reason, fast and accurate diagnostics in the field of ophthalmology are essential. Two examination techniques, full-field ERG and pupillometry were combined in a diagnostic device developed by ICM e.V. to reduce the examination process for both examiners and patients. In this paper, the device is examined for the quality of the full-field ERG measurements. A feasibility study with 12 healthy subjects (3 f, 9 m, 36.33 ± 11.94 years) was conducted to evaluate the device. The results showed that the peak times for both light- and dark-adapted measurements were within the range of the researched literature values. However, the amplitudes were markedly lower in both measurements compared to the averaged literature values (dark-adapted about 8.5-fold and light-adapted about 5.5-fold) and are clearly outside the range of values researched. The main reason for this is the use of cup electrodes, which were placed on the skin of the lower eyelid. Nevertheless, plausible and comparable analysis values could be obtained with the eye diagnostic device PEP-2000. Further studies with wire electrodes will be performed.
Haptically enhanced VR surgical training system
Authors: Preiss Maximilian , Walder Alexander , Kim Yeongmi
Published: September 2022

This paper proposes a cost-effective VR surgical training system which computes haptic feedback forces when a VR surgical tool interacts with virtual tissues. A 3 degrees of freedom (DoF) reverse linear Delta mechanism is used to render computed force feedback data which are then received by the fingertip of the operator. Additionally, the moving plate allows rendering of surface properties and lateral forces occurring due to a tumor with different stiffness parameters below the skin surface. Controllers are designed and implemented to regulate the haptic feedback device’s end-effector position and applied force. The virtual surgical instruments are controlled by a 7DoF serial link manipulator which captures the operator’s movement by the utilization of various sensors. The controllers to regulate forces as well as the positions are evaluated with the proposed haptic feedback device. The mean RMSE of the force and mean error of the angular displacement are 0.0707 N and 1.95°, respectively. The presented system can provide multisensory feedback including visual, auditory and haptic feedback interactively depending on the operator’s input in the presented VR surgical training system.