Current Directions in Biomedical Engineering

Open Access Published by De Gruyter

Volume 2 Issue 1

Issue of Current Directions in Biomedical Engineering

Contents
Journal Overview

Open Access September 30, 2016

Synthesis and characterization of PIL/pNIPAAm hybrid hydrogels

Sylvia Pfensig, Daniela Arbeiter, Klaus-Peter Schmitz, Niels Grabow, Thomas Eickner, Sabine Illner

Page range: 1-4

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Abstract

In this study, varying amounts of NIPAAm and an ionic liquid (IL), namely 1-vinyl-3-isopropylimidazolium bromide ([ViPrIm] + [Br] − ), have been used to synthesize hybrid hydrogels by radical emulsion polymerization. Amounts of 70/30%, 50/50%, 30/70%, 15/85% and 5/95% (wt/wt) of PIL/pNIPAAm were used to produce hybrid hydrogels as well as the parental hydrogels. The adhesive strength was investigated and evaluated for mechanical characterization. Thermal properties of resulting hydrogels have been investigated using differential scanning calorimetry (DSC) in a default heating temperature range (heating rate 10 K min −1 ). The presence of poly ionic liquids (PIL) in the polymer matrix leads to a moved LCST (lower critical solution temperature) to a higher temperature range for certain hybrid hydrogels PIL/pNIPAAm. While pNIPAAm exhibits an LCST at 33.9 ± 0.3°C, PIL/pNIPAAm 5/95% and PIL/pNIPAAm 15/85% were found to have LCSTs at 37.6 ± 0.9°C and 52 ± 2°C, respectively. This could be used for controlled drug release that goes along with increasing body temperature in response to an implantation caused infection.

Conventional permanent stent systems for vascular applications are associated with long-term risks, such as restenosis and thrombosis. To overcome these limitations, novel approaches using various biodegradable materials for stent construction have been investigated. In this context, thermal treatment of polymer materials is investigated to adjust the mechanical properties of biodegradable stents. In this work polymeric tubular specimens of biodegradable poly(L-lactide) (PLLA) were extruded and subjected to a molding process using different temperatures above glass transition temperature T G . Physicochemical properties of the molded samples were analyzed using DSC measurements and uniaxial tensile tests. The molding process resulted in a weakening of the PLLA tubular specimens with a simultaneous increase in the degree of crystallinity ( χ ).

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”.

The microfabrication and packaging of novel, three-dimensional, polyimide-based, highly flexible, microscale electrocorticography multi-electrode arrays for enhanced epicortical recording of local field potentials is presented. A polyimide foil embeds metallic structures relating to 32 taper-type electrode sites, contact pads as well as interconnecting conductor paths which are integrated in the planar portion of the electrode substrate material. Circular exposed and, thus, active electrode sites are 50 μm in diameter and employed center-to-center pitches range from 250 μm to 1 mm, respectively. As-fabricated 3D-μECoG-MEAs provide taper heights of approximately 4 μm as well as 59 μm being distinguished by characteristic impedances of about 368.9 kΩ at 1 kHz measured in saline electrolyte. The applied packaging strategies favor flip-chip bonding and vapor phase soldering of the polymer substrates to customized printed circuit boards.

Two dimensional pelvic intraoperative neuromonitoring (pIONM ® ) is based on electric stimulation of autonomic nerves under observation of electromyography of internal anal sphincter (IAS) and manometry of urinary bladder. The method provides nerve identification and verification of its’ functional integrity. Currently pIONM ® is gaining increased attention in times where preservation of function is becoming more and more important. Ongoing technical and methodological developments in experimental and clinical settings require further analysis of the obtained signals. This work describes a postprocessing algorithm for pIONM ® signals, developed for automated analysis of huge amount of recorded data. The analysis routine includes a graphical representation of the recorded signals in the time and frequency domain, as well as a quantitative evaluation by means of features calculated from the time and frequency domain. The produced plots are summarized automatically in a PowerPoint presentation. The calculated features are filled into a standardized Excel-sheet, ready for statistical analysis.

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.

Ensuring optimal climate conditions during cultivation is essential for successful and reproducible cell culture based investigation. Being the gold standard, carbon dioxide incubators fulfill this demand in various geometries and sizes to suit diverse cultivation applications. A door opening results in a climate breakdown followed by a restoration period during which optimal conditions cannot be guaranteed. The following paper investigates the influence of incubator door design to optimize climate retainment during the above mentioned event.

The aim of this work was to analyse the medication process and the potential for errors during the process steps. For this purpose, a literature review was conducted and a questionnaire was developed to compare the results from the literature with the current medication process in Styrian hospitals. The questionnaire was divided into four different parts with a total of 29 questions. For the survey all 37 Styrian hospitals were contacted whereas 11 filled out the questionnaire. The survey showed that there is no standardized medication process defined and that the rate of medication errors is generally underestimated. In addition, technical solutions may help to reduce errors but are expected to be hardly used in clinical practice.

Open Access September 30, 2016

Control tower to surgical theater

Clinical engineer as a leader of productive process in operating room block

Matteo Buccioli, Leo Traldi

Page range: 345-349

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Abstract

The main social priority is to reduce public debt and to streamline national health service (NHS) costs. Consequently, health managers need to acquire operating methods within their managerial structures so that all available resources are better planned in terms of effectiveness and efficiency, without compromising patient safety. In order to identify the information categories needed to know the whole surgical process is necessary to divide these in two main categories, supply and demand . Demand Information Group (DIG) contains the information that identify patients and its needs in terms of care. Instead Supply Information Group (SIG) contains information about hospital resources in order to cover the supply. The surgical process analyzed in terms such as industrial production process has the goal of produce the “ health product for the patient ” and its central part is performed in the operating room by a surgical team. This does not mean that the precedent and subsequent phases of the operating room have minor importance, in fact to obtain a high quality “ health product ” and reduce to a minimum the clinical risks related to the patient it is necessary that each phase of the process is carried out in the right way. The implementation of a Control Tower Approach allows for the management of productive process, able to guide hospital managers to identify the best strategies and to improve the risk management of patient safety in response to the guidelines of the World Health Organization.

Open Access September 30, 2016

Development of a skull phantom for the assessment of implant X-ray visibility

Thomas Hoffmann, Fabian Klink, Axel Boese, Karin Fischer, Oliver Beuing, Georg Rose

Page range: 351-354

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Abstract

The paper presents the development and test of a skull phantom, which can be used for the assessment of the radiographic visibility of neurovascular implants. State of the art methods are based on specimens of the human skull. These are highly individual and not suitable for comparison of different radiographic data sets. The development process of the skull phantom is described from data generation to image processing, design and manufacturing using 3D printing. An experimental setup is recommended to generate reproducible data sets for implant visibility assessment with bone mimicking structures of the phantom. The model is evaluated by qualitative comparison with equivalent data sets of the original human skull model. The results show, that contrast characteristics of the phantom and the human skull model are similar. X-ray attenuation of the human bone is higher than the polymeric phantom material. The introduced phantom allows the determination of X-ray attenuation characteristics of different neurovascular implants for medical approval and testing processes.

The treatment of otitis media requires classifying the effusion in the tympanic cavity for choosing appropriate therapeutic strategies. Otoscopic examination of the middle ear depends on the expertise of the physician and is often hampered in case of inflammatory alterations of the tympanic membrane. In otologic research, optical coherence tomography is an innovative non-invasive imaging technique utilized for visualizing the tympanic membrane. This ex vivo study presents the possibility of OCT and Doppler-OCT for the detection of effusions in the tympanic cavity. Structural OCT imaging allows the direct visualization of scattering fluids behind the tympanic membrane. In addition, the measurement of the reduced oscillation amplitude by means of Doppler-OCT permits the indirect detection of scattering and transparent fluids.

This paper describes a prototype of an automatic system for the detection and evaluation of Cystic fibrosis features (CF) in High resolution computed tomography (HRCT) Scans. The aim of this study lies in presenting this system as a decision support tool for radiologists in future. The CF features that have been detected and evaluated are Bronchiectasis and Mucus Plugging. This system recognizes Bronchiectasis as the presence of enlarged airways in pulmonary CF-CT slices whereas, Mucus Plugging has been recognized as clusters of high attenuation pixels. The dataset of this study consists of HRCT Scans of five CF patients of varying disease stages. Mean percentages of these CF features that were computed for each intercostal space, starting from the first to the fifth, fairly accurately match the different stages of the disease.

Lifetime estimation of implanted electronics in hermetic packages requires the prediction of the humidity induced lifetime. Classical approaches are limited in applications where miniaturized packages and a buffered humidity at low values are being utilized. An approach to overcome these limitations is described and investigations on suitable materials and measurement setups are presented. The findings support the usability of a Zeolite-silicone based desiccant system as a dielectric for a new type of online sensor. The future exploitation of this new sensing principle can allow the monitoring and prediction of humidity conditions inside of highly reliable miniaturized hermetic implantable packages.

Carbon fiber reinforced polyetheretherketone (CFR-PEEK) has similar mechanical properties to human bone and is considered as the best alternative material to substitute titanium for spine cage implants. To compensate its poor osteogenic properties and limited bioinertness, CFR-PEEK was coated with a thin film of titanium. In the study, we investigated the biological response in vitro of titanium coated CFR-PEEK with different vacuum plasma pretreatments. The so modified surface revealed first hints for a good cell response by excellent cell adhesion and morphology of human osteoblast – like cells MG 63 (ATXX:’CRL-1427). Thus, the findings show that surface roughness of CFR-PEEK material has a profound effect on the biological activity via vacuum plasma treatment.

Open Access September 30, 2016

Wear of a total intervertebral disc prosthesis

Abrasion tests of a tribological system of total intervertebral disc prosthesis with dampening characteristics

Carina Micheler, Erhard Krampe, Peter Foehr, Miriam Haerst, Rainer Burgkart

Page range: 573-576

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Abstract

In this study we characterized the wear behavior of a tribological system with material combinations of the total intervertebral disc prosthesis InDisc (Institute of Medical and Polymer Engineering) – consisting of two laser sintered titanium alloy plates with an elastomer inbetween. For the tests a translatory oscillation test bench was used which simulates the kinematic and the physiological environment of the lumbar spine. In the interface between the elastomer (Silopren LSR 2670) and the laser sintered titanium alloy (Ti6Al4V) abrasion cords out of silicone rubber with a maximal area of 500 × 700 μm 2 were generated as well as individual particles with a size of 10 × 20 to 40 × 50 μm 2 . In the second prosthesis interface of Ti6Al4V and bone, bone particles with an area of 0.5 × 0.5 to 1 × 1 μm 2 were detected. The wear particles and the amount of wear volume influence the biological response of a total intervertebral disc prosthesis in the body.

Open Access September 30, 2016

Digital health and digital biomarkers – enabling value chains on health data

Sven Meister, Wolfgang Deiters, Stefan Becker

Page range: 577-581

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Abstract

Smart Devices, IoT and Co. are changing healthcare. The possibilities for pervasive sensing and analysis are fast increasing and new therapy concepts as well as business models are arising, related to the term “Digital Health”. The paper will give a brief overview on the history and ask, whether Digital Health is more than Telemedicine 4.0. Furthermore, we will ask for the prospective currency to participate in new preventive offer. Data is the new oil – Digital Biomarkers enable new value chains on health data and allow for the personalization of healthcare. We will present ongoing work of Fraunhofer ISST on a Digital Biomarker called beHealthy Health Score.

Mathematical models can be employed to simulate a patient’s individual physiology and can therefore be used to predict reactions to changes in the therapy. To be clinically useful, those models need to be identifiable from data available at the bedside. Gradient based methods to identify the values of the model parameters that represent the recorded data highly depend on the initial estimates. The proposed work implements a previously developed method to overcome those dependencies to identify a three parameter model of gas exchange. The proposed hierarchical method uses models of lower order related to the three parameter model to calculate valid initial estimates for the parameter identification. The presented approach was evaluated using 12 synthetic patients and compared to a traditional direct approach as well as a global search method. Results show that the direct approach is highly dependent on how well the initial estimates are selected, while the hierarchical approach was able to find correct parameter values in all tested patients.

During a magnetic resonance imaging (MRI) exam, a respiratory signal can be required for different purposes, e.g. for patient monitoring, motion compensation or for research studies such as in functional MRI. In addition, respiratory information can be used as a biofeedback for the patient in order to control breath holds or shallow breathing. To reduce patient preparation time or distortions of the MR imaging system, we propose the use of a contactless approach for gathering information about the respiratory activity. An experimental setup based on a commercially available laser range sensor was used to detect respiratory induced motion of the chest or abdomen. This setup was tested using a motion phantom and different human subjects in an MRI scanner. A nasal airflow sensor served as a reference. For both, the phantom as well as the different human subjects, the motion frequency was precisely measured. These results show that a low cost, contactless, laser-based approach can be used to obtain information about the respiratory motion during an MRI exam.

Realistic training of cardiologic interventions in a heart catheter laboratory is hardly achievable with simple tools and requires animal experiments. Therefore, first a simple mock circuit connected to a porcine heart mimicking the natural heart motion was developed. In a second step the setup was duplicated to drive both sides of the heart independently to generate motion and physiologic pressures and flows. Using this simple setup cardiologic interventions (arterial and ventricular septal defects ASD/VSD closure) were performed successfully and allowed realistic training under the C-arm, echocardiography, placement of catheters and repair of ASD/VSD. With the second setup flows of up to 4 l/min were achieved in both sides of the heart at maximum left and right ventricular pressures of 80 mm Hg and 30 mm Hg respectively. This method is inexpensive and represents a realistic alternative to training in animal experiments.

About this journal

Objective
Current Directions in Biomedical Engineering (CDBME) is an open access journal and closely related to the journal Biomedical Engineering - Biomedizinische Technik (BME-BMT) that is well established and of high quality for more than 50 years. CDBME is as BME-BMT a forum for the exchange of knowledge in the fields of biomedical engineering, medical information technology and biotechnology/bioengineering for medicine and addresses engineers, natural scientists, and clinicians working in research, industry, or clinical practice.

Topics

Diagnostic Imaging
Biosignal Processing, Biomechanics, Image Processing, Modelling and Simulation
Information and Communication in Medicine, Telemedicine and e-Health
Surgery, Minimum Invasive Interventions, Endoscopy and Image Guided Therapy
Diagnostic and Therapeutic Instrumentation, Clinical Engineering
Micro- and Nanosystems in Medicine, Active Implants, Biosensors
Neuroengineering, Neural Systems, Rehabilitation and Prosthetics
Biomaterials, Cellular and Tissue Engineering, Artificial Organs
Biomedical Engineering for Audiology, Ophthalmology, Emergency and Dental Medicine

Article formats
Conference Proceedings

Volume 2 Issue 1

Issue of Current Directions in Biomedical Engineering

Synthesis and characterization of PIL/pNIPAAm hybrid hydrogels

Abstract

Novel blood protein based scaffolds for cardiovascular tissue engineering

Electrospinning of a novel autologous scaffold with enhanced hemocompatibility and appropriate biostability in aqueous solution

Abstract

Cell adhesion and viability of human endothelial cells on electrospun polymer scaffolds

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Effects of heat treatment and welding process on superelastic behaviour and microstructure of micro electron beam welded NiTi

Abstract

Long-term stable modifications of silicone elastomer for improved hemocompatibility

Abstract

The effect of thermal treatment on the mechanical properties of PLLA tubular specimens

Abstract

Biocompatible wear-resistant thick ceramic coating

Characterization of the hardness and porosity

Abstract

Protection of active implant electronics with organosilicon open air plasma coating for plastic overmolding

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Examination of dielectric strength of thin Parylene C films under various conditions

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Open air plasma deposited antimicrobial SiOx/TiOx composite films for biomedical applications

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Systemic analysis about residual chloroform in PLLA films

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A macrophage model of osseointegration

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Towards in silico prognosis using big data

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Technical concept and evaluation of a novel shoulder simulator with adaptive muscle force generation and free motion

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Usability evaluation of a locomotor therapy device considering different strategies

Abstract

Hypoxia-on-a-chip

Generating hypoxic conditions in microfluidic cell culture systems

Abstract

Integration of a semi-automatic in-vitro RFA procedure into an experimental setup

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Fabrication of MEMS-based 3D-μECoG-MEAs

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High speed digital interfacing for a neural data acquisition system

Enabling of live display functionality for a neural recording system

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Bionic forceps for the handling of sensitive tissue

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Experimental studies on 3D printing of barium titanate ceramics for medical applications

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Patient specific root-analogue dental implants – additive manufacturing and finite element analysis

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3D printing – a key technology for tailored biomedical cell culture lab ware

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3D printing of hydrogels in a temperature controlled environment with high spatial resolution

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Biocompatibility of photopolymers for additive manufacturing

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Biochemical piezoresistive sensors based on pH- and glucose-sensitive hydrogels for medical applications

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Novel wireless measurement system of pressure dedicated to in vivo studies

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Portable auricular device for real-time swallow and chew detection

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Detection of miRNA using a surface plasmon resonance biosensor and antibody amplification

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Simulation and evaluation of stimulation scenarios for targeted vestibular nerve excitation

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Deep brain stimulation: increasing efficiency by alternative waveforms

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Prediction of immediately occurring microsleep events from brain electric signals

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Determining cardiac vagal threshold from short term heart rate complexity

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Classification of cardiac excitation patterns during atrial fibrillation

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An algorithm to automatically determine the cycle length coverage to identify rotational activity during atrial fibrillation – a simulation study

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Deriving respiration from high resolution 12-channel-ECG during cycling exercise

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Reducing of gradient induced artifacts on the ECG signal during MRI examinations using Wilcoxon filter

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Open air plasma deposited antimicrobial SiO_x/TiO_x composite films for biomedical applications

An automatic systolic peak detector of blood pressure waveforms using 4^th order cumulants