Tarek Elsarnagawy

Reconstruction of quasi-radial dipolar activity using three-component magnetic field measurements

OBJECTIVE While standard magnetoencephalographic systems record only one component of the biomagnetic field, novel vector-biomagnetometers enable measurement of all three components of the field at each sensing point. Because information content in standard one-component magnetoencephalography (MEG) is often not adequate to reconstruct quasi-radial dipolar activity, we tested the hypothesis that quasi-radial activity can be estimated using three-component MEG. METHODS We stimulated the right median nerve in 11 healthy volunteers and recorded the somatosensory evoked fields over the contralateral hemisphere using a novel vector-biomagnetometer system comprised of SQUID-based magnetometer triplets. Source reconstruction for the early cortical components N20m and P25m was subsequently performed. RESULTS Both tangential and quasi-radial dipolar activity could be reconstructed in 10 of the 11 participants. Dipole locations were found in the vicinity of the central sulcus, and dipole orientations were predominantly tangential for N20m and quasi-radial for P25m. The mean location difference between the tangential and quasi-radial dipoles was 11.9 mm and the mean orientation difference was 97.5°. CONCLUSIONS Quasi-radial dipolar activity can be reconstructed from three-component magnetoencephalographic measurements. SIGNIFICANCE Three-component MEG provides higher information content than does standard MEG.

Thermoforming techniques for manufacturing porous scaffolds for application in 3D cell cultivation

Within the scientific community, there is an increasing demand to apply advanced cell cultivation substrates with increased physiological functionalities for studying spatially defined cellular interactions. Porous polymeric scaffolds are utilized for mimicking an organ-like structure or engineering complex tissues and have become a key element for three-dimensional (3D) cell cultivation in the meantime. As a consequence, efficient 3D scaffold fabrication methods play an important role in modern biotechnology. Here, we present a novel thermoforming procedure for manufacturing porous 3D scaffolds from permeable materials. We address the issue of precise thermoforming of porous polymer foils by using multilayer polymer thermoforming technology. This technology offers a new method for structuring porous polymer foils that are otherwise available for non-porous polymers only. We successfully manufactured 3D scaffolds from solvent casted and phase separated polylactic acid (PLA) foils and investigated their biocompatibility and basic cellular performance. The HepG2 cell culture in PLA scaffold has shown enhanced albumin secretion rate in comparison to a previously reported polycarbonate based scaffold with similar geometry.

Bioelectric and biomagnetic measurements are differentially sensitive to spiral currents.

Abstract Observations indicate that different information is contained in electrocardiograms and magnetocardiograms in both patients and healthy volunteers. Closed loop currents could explain this phenomenon. We hypothesized that open loops, such as the spirally shaped currents in the heart, also contribute to these differences. We modeled two types of open spiral-shaped loops, based on the heart geometry, using 12 artificial current dipoles in a physical torso phantom. The electric potentials and magnetic fields were measured simultaneously with increasing numbers of active dipoles in the spiral source geometries. We found a continuous increase in the measured amplitudes of the magnetic fields, up to a plateau value when 10 active dipoles were enabled. For the electric potentials, we found that the amplitudes increased when up to six or eight active dipoles had been enabled, and then decreased thereafter. We conclude that open loop currents also contribute to the experimentally observed differences in magnetocardiograms and electrocardiograms in both patients and healthy volunteers. Combined bioelectric and biomagnetic measurements should provide greater insight into heart activity than do single modality measurements.

Investigating the Prospective Use of Fibre-Optics-based Sensors in Dentistry (Die Untersuchung der Einsatzmöglichkeiten faseroptischer Sensoren in der Zahnmedizin)

This study aims at comparing the technology of fibre optics to that of electrical strain gauges (ESG) when both are used in the field of dentistry. It compares the accuracy and sensitivity of the strain gauges versus that of optical fibres under the same loading conditions. Results showed that the accuracy of strain gauges is slightly better than that of fibre optics sensor (FOS). However, the errors in the fibre readings showed a pattern that was repeatable in every measurement series and therefore could be corrected through a simple calibration procedure. On the other hand the sensitivity of the FOS was much better than the ESG. Results also showed that using optical sources of lower wavelength improved the sensitivity as well as the accuracy of the optical system. Ziel dieser Studie ist der Vergleich zwischen Sensoren auf der Basis von Glasfasertechnologien und elektrischen Dehnungsmessstreifen (DMS) unter dem Gesichtspunkt der Anwendung in der Zahnmedizin. Die Studie vergleicht die Empfindlichkeit des faseroptischen Sensors (FOS) gegenüber der des DMS bei Krafteinwirkung. Unter anderem zeigte sich, dass der vorhandene Linearitätsfehler beim FOS von systematischer Art ist (wiederholbares Muster). Dieser Fehler kann durch einfache Kalibrierungsprozeduren behoben werden. Weiterhin verbesserte sich sowohl die FOS-Genauigkeit als auch die Empfindlichkeit durch das Einsetzen von Laserquellen kürzerer Wellenlänge. Alle Ergebnisse werden im Text dargestellt und diskutiert.

A fibre optic sensor for ambiguity measurement of apparent strain produced by electrical strain gauge-transient-heating-effect

Strain gauges are useful sensors in many engineering and medical applications. In case of using one gauge for measurement; quarter-bridge configurations, current flowing when power is delivered to the electrical strain gauge causes temperature rise; transient heat effect (THE); and consequently apparent strain appearing as drift of the zero baseline. Fiber optics has been used to measure both temperature and strain or force. The aim of this study is to evaluate temperature rise produced by the electrical strain gauge and in accordance determine the equivalent apparent strain as a step towards using the reading to correct for the error due to the (THE). Results of this study showed that optical fibers sensor is more sensitive compared to the semiconductor sensor which has been used as a reference temperature sensor. Results, also showed the feasibility of determining the equivalent apparent strain values through reverse calculation of number of fringes resulting from the fiber optic sensor due to the temperature change. This was as an initial step to implement those values in the measuring electronic circuitry in order to eliminate the drift in the zero baselines. Uses of such fiber optic sensors are very useful when conducting high precision measurements and in measuring the ambiguity of the electrical gauge sensing system as well as eliminating such ambiguity.

A Fibre Optic Sensor for Ambiguity Measurement of Apparent Strain Produced by Electrical Strain Gauge-Transient-Heating-Effect

Abstract Strain gauges are useful sensors in many engineering and medical applications. When using one gauge for the measurement in quarter-bridge configurations, the elctrical current flowing delivers power to the electrical strain gauge which causes a temperature rise (transient heat effect or THE), with a strain signal appearing as drift of the zero baseline. Fibre optic sensors on the other side are used to measure temperature as well as strain or force. The aim of this study is to evaluate the rise in temperature produced by the electrical strain gauge and to determine the equivalent apparent strain accordingly as a step towards using the reading to correct for the error due to the THE. The results of this study show that the optical fibre sensor is more sensitive compared to the semiconductor sensor used as a reference temperature sensor. The results also show the feasibility of determining the equivalent apparent strain values through reverse calculation of number of fringes resulting from the fibre optic sensor due to the temperature change. This was as an initial step to implement those values in the measuring electronic circuitry in order to eliminate the drift in the zero baselines.

A case study on benchmarking for biomedical engineering study programs

This study presents the experience of the Department of Applied Medical Sciences (AMS) - Riyadh Community College - King Saud University in its way to achieve the international accreditation standards to ensure quality. The study is based on a three years experience (2008–2010). The following will be clarified, the list of criteria adopted by AMS to ensure quality and the procedures adopted by AMS to apply accreditation standards to ensure quality of outputs.The study followed the iterative descriptive approach in analyzing the topics. The results show the procedures how the standards were applied to ensure the quality of outputs by meeting the requirements in all aspects, national and international, especially of the internationally recognized organization Council on Occupational Education COE, by which the AMS was then accredited in June 2010. A four year development strategic plan is set for the department to ensure consistent quality and improvement standards. By reviewing the literature of former experiences of Arab and international bodies for accreditation and quality assurance, the study concluded a list of accreditation criteria and indicators of quality assurance, as well as indicators to ensure the quality of the university environment. The achieved number of accreditation and quality assurance standards are presented from both national and international organizations and were found to be: 25 accreditation standards leading to 245 indicators, and 41 indicators for QA, and 29 indicators for the QA of the university environment.The study recommended the need to activate the academic accreditation and assessment of academic programs periodically internally and externally. Furthermore, similar departments of applied medical sciences should adopt the presented accreditation and quality assurance principles. In addition those departments are asked to put a strategic plan that meets their needs and goals.

Effect of the Embedding Technique in Fibre-Optic-Based Force Sensor for Dentistry: Nano-strain AnalysisFaserkraftsensor im Nanodehnungsbereich für Dentalanwendungen

Abstract The aim of this study is to evaluate the ability of fibre optics in measuring nano-strains developed in dentistry due to small chewing force. Since long fibres were used before, therefore, short fibres were evaluated in this study. In this direction the results from three short fibres sensors (coated with adhesive, coated without adhesive, and uncoated with adhesive) were collected. The results were compared to each other and to strain values from electrical strain gauge. The results revealed superiority of the short fibre with adhesive among all the sensors in sensitivity and accuracy including the strain gauge. The results of the short fibre were, then, compared to results of previous study long fibre. Again, the accuracy of the short fibre sensor was higher than that of the long fibre (deviation of 3% and 12% errors, respectively). In terms of sensitivity, the sensitivity of the short fibre was about 30% of the long fibre. However, sensitivities of both short and long fibres were in the nano-strain region (74 and 17 nano-stains respectively) and were much higher than electrical strain gauge (micro-strain range).

Cooperative Education Program in Medical Equipment Technology Education

The paper reviews selected definitions of certain terms which are important to know for the interactions of all participants in a cooperative and educational training program. It describes details how the COOP program is developed to closely match the National Qualifications Framework designed by the Saudi National Commission on Academic Accreditation and Assessment (NCAAA). Within this applied research results of the COOP Program at King Saud University, an infrastructure is developed and applied on students registered for the associate degree program in the medical equipment technology in terms. This covers time planning and skills to be acquired during the training and most important departments and medical devices that must be accessible to the student,. All results and statistics are presented and discussed as well as ways of improvement.

A High Resolution Interferometric Fiber-Optic Temperature Sensor "FOTS"

This paper introduces an application of a single-mode optical fiber as a temperature sensor. The application is based on the Michelson-interferometer principle. A single mode optical fiber of several meters is loosely wound around a foam cylinder. The interferometric principle used in this work gives the advantage of having the output directly as a digital readout after converting it into electrical signal. The detected number of counts (fringes) directly represents the increase or decrease in temperature. The output of the fiber optic sensor is compared to that of a semiconductor temperature sensor gauge. The correlation between the two sensors is presented. Results from the fiber optic sensor introduced within this article show high sensitivity in the range of 52middot10-4degC, stability and reproducibility. Finally, the obtained sensitivity proved to be very high compared to other techniques used in most published articles of fiber optic temperature sensors. In addition to the high sensitivity the FOTS introduced in this work is versatile and may serve many applications where temperature plays an important role and very small fluctuations have to be registered.