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Bereich: Suchergebnisse
Publikation Hematocrit measurement - a high precision on-line measurement system based on impedance spectroscopy for use in hemodialysis machines(2009) Trebbels, Dennis; Zengerle, Roland; Hradetzky, DavidThis paper presents a unique technical approach to measure the proportion of blood volume occupied by red blood cells, the hematocrit value (HCT) on-line and in-line. A practical method has been developed to measure without the need for extracting blood samples out of an existing extracorporeal blood circulation system. The new sensor is based on Impedance Spectroscopy and measures electrical properties of the blood at various frequencies. In order to achieve the required precision resolution the sensor geometry has been optimized by Finite Element Analysis. For sensor readout a digital measurement circuitry based on cheap standard components is developed and allows practical implementation of HCT-sensor devices for the first time. Special care has been taken in order to compensate for the temperature effects.04B - Beitrag KonferenzschriftPublikation Interferometric label-free biomolecular detection system(IOP Publishing Ltd, 2006) Hradetzky, David; Mueller, Claas; Reinecke, HolgerThis work presents a simple evanescent wave sensing system based on an interferometric approach, suitable to meet the requirements of label-free sensor systems for detecting biomolecular interactions. It represents a basic concept towards label-free detection systems in various applications. The basic objectives of transducers for evanescent wave sensing are discussed. An optical detection system based on a interferometric approach using Young's double slit configuration is discussed, set-up and characterized. With refractometric measurements of various sucrose dilutions, the performance of the pure optical set-up is evaluated.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Interferometric sensor platform for biomolecular interaction analysis(VDE, 2005) Hradetzky, David; Müller, Claas; Reinecke, Holger04B - Beitrag KonferenzschriftPublikation Interferometrisches Biosensor System(2001) Wikerstål, Andreas; Brandenburg, Albrecht; Hradetzky, David; Krauter, Ralf; Künzel, Christa; Schulte, Heinrich; Stefan, Monika04B - Beitrag KonferenzschriftPublikation Label free detection of biomolecular interactions(IEEE, 2005) Hradetzky, David; Müller, Claas; Reinecke, HolgerThis work presents a simple evanescent wave sensing system based on an interferometric approach suitable to meet the demands on label free sensor systems for the detection of biomolecular interactions especially. It is representing a basic concept towards high throughput application. The system performance and reproducibility was evaluated with refractometric measurements of sucrose dilutions. A mean resolution of the effective refractive index of 3sigma(Deltamacrnmacr eff )=0.9middot10 -6 without averaging and a reproducibility below sigma r =0.1middot10 -6 were achieved. The suitability for the detection of biomolecular interactions was validated with the detection of a DNA hybridization04B - Beitrag KonferenzschriftPublikation Eye-Cam: Sprachgesteuerte Miniaturkamera integriert in einer Brille(2007) Hradetzky, David; Kliche, Kurt; Ehrbrecht, Bernd; Anka, Laszlo; Wölfle, Matthias; Zengerle, Roland04B - Beitrag KonferenzschriftPublikation Miniaturisierte Sensorplattform zur markierungsfreien Detektion biomolekularer Interaktionen(Cuvillier Verlag, 2005) Hradetzky, David02 - MonographiePublikation Capacitive on-line hematocrit sensor design based on impedance spectroscopy for use in hemodialysis machines(IEEE, 2009) Trebbels, D.; Hradetzky, David; Zengerle, R.This paper presents a new design for an on-line and in-line hematocrit (HCT) sensor. Special feature of the sensor is the capability to measure the hematocrit of a blood sample inside standard plastic tubing widely used in medical equipment. No blood sample has to be extracted out of existing extracorporeal blood circulation systems such as hemodialysis machines or heart-lung machines. The sensor principle is based on electrical impedance spectroscopy. Dielectric properties of the blood and the plastic tubing are measured at various frequencies. In order to optimize the sensitivity, a unique electrode configuration is developed and optimized by Finite Element Simulation. The new electrode design optimizes the overall sensitivity of the sensor towards a change in dielectric properties of the blood caused by the HCT value and therefore decreases the sensitivity to side effects caused by temperature drift and component tolerances. As a result of the optimized overall sensor performance the complexity of a sensor readout circuitry can be reduced to a minimum which leads to an unmatched price-performance ratio for a complete measurement system.04B - Beitrag Konferenzschrift