Dr.-Ing. Matthias Gräser

Universitätsklinikum Hamburg-Eppendorf (UKE)
Sektion für Biomedizinische Bildgebung
Lottestraße 55
2ter Stock, Raum 212
22529 Hamburg

Technische Universität Hamburg (TUHH)
Institut für Biomedizinische Bildgebung
Gebäude E, Raum 4.044
Am Schwarzenberg-Campus 3
21073 Hamburg

Tel.: 040 / 7410 25812
E-Mail: matthias.graeser(at)tuhh.de
E-Mail: ma.graeser(at)uke.de

Research Interests

  • Magnetic Particle Imaging
  • Low Noise Electronics
  • Inductive Sensors
  • Passive Electrical Devices

Curriculum Vitae

Matthias Gräser submitted his Dr.-Ing. thesis in january 2016 at the institute of medical engineering (IMT) at the university of Lübeck and is now working as a Research Scientist at the institute for biomedical imaging (IBI) at the technical university in Hamburg, Germany.  Here he develops concepts for Magnetic-Particle-Imaging (MPI) devices. His main aim is to improve the sensitivity of the imageing devices and improve resolution and application possibilities of MPI technology.

In 2011 Matthias Gräser started to work at the IMT as a Research Associate in the Magnetic Particle Imaging Technology (MAPIT) project. In this project he devolped the analog signal chains for a rabbit sized field free line imager. Additionally he developed a two-dimensional Magnetic-Particle-Spectrometer. This device can apply various field sequences and measure the particle response with a very high signal-to-noise ratio (SNR).

The dynamic behaviour of magnetic nanoparticles is still not fully understood. Matthias Gräser investigated the particle behaviour by modeling the particle behaviour with stochastic differential equations. With this model it is possible to simulate the impact of several particle parameters and field sequences on the particle response .

In 2010 Matthias Gräser finished his diploma at the Karlsruhe Institue of Technology (KIT). His diploma thesis investigated the nerve stimulation of magnetic fields in the range from 4 kHz to 25 kHz.

Journal Publications

[76865]
Title: A device for measuring the trajectory dependent magnetic particle performance for {MPI}.
Written by: M. Graeser, M. Ahlborg, A. Berends, K. Bente, G. Bringout, C. Debbeler, A. von Gladiss, K. Gräse, C. Kaethner, S. Kaufnamm, K. Lüdtke-\-Buzug, H. Medimagh, J. Stelzner, M. Weber, and T. M. Buzug
in: <em>5th International Workshop on {Magnetic Particle Imaging} ({IWMPI}), IEEE Xplore Digital Library</em>. (2015).
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DOI: 10.1109/IWMPI.2015.7107078
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[BibTex]

Note: inproceedings

Abstract: In ferrofluids, the magnetization undergoes magnetic relaxation processes, which are affected by the concentration of the fluid, the viscosity of the medium, the strength and frequencies of an external magnetic field and the structure of the magnetic core [1,2]. In many models the particles are assumed to have an uniaxial anisotropy that results in one preferred magnetization direction called the easy axis. If the particles are exposed to a magnetic field that is aligned with this easy axis, the corresponding signal response is higher compared to other excitation directions [3]. For a one dimensional excitation this alignment will be reached shortly if the particle is able to mechanically rotate and the hydrodynamic friction is low. In more dimensional excitations, such as in dynamic field free line ({FFL}) scanners, or in field free point ({FFP}) scanners, the excitation direction changes constantly [4]. If this change in direction exceeds the maximum mechanical rotation speed of the particles, they are not able to align. As a result, the particle signal will drop. In this work, we present a new device that is able to generate {FFP} and {FFL} field sequences while applying different possible offset fields.

Conference Proceedings

[76865]
Title: A device for measuring the trajectory dependent magnetic particle performance for {MPI}.
Written by: M. Graeser, M. Ahlborg, A. Berends, K. Bente, G. Bringout, C. Debbeler, A. von Gladiss, K. Gräse, C. Kaethner, S. Kaufnamm, K. Lüdtke-\-Buzug, H. Medimagh, J. Stelzner, M. Weber, and T. M. Buzug
in: <em>5th International Workshop on {Magnetic Particle Imaging} ({IWMPI}), IEEE Xplore Digital Library</em>. (2015).
Volume: Number:
on pages:
Chapter:
Editor:
Publisher:
Series:
Address:
Edition:
ISBN:
how published:
Organization:
School:
Institution:
Type:
DOI: 10.1109/IWMPI.2015.7107078
URL:
ARXIVID:
PMID:

[BibTex]

Note: inproceedings

Abstract: In ferrofluids, the magnetization undergoes magnetic relaxation processes, which are affected by the concentration of the fluid, the viscosity of the medium, the strength and frequencies of an external magnetic field and the structure of the magnetic core [1,2]. In many models the particles are assumed to have an uniaxial anisotropy that results in one preferred magnetization direction called the easy axis. If the particles are exposed to a magnetic field that is aligned with this easy axis, the corresponding signal response is higher compared to other excitation directions [3]. For a one dimensional excitation this alignment will be reached shortly if the particle is able to mechanically rotate and the hydrodynamic friction is low. In more dimensional excitations, such as in dynamic field free line ({FFL}) scanners, or in field free point ({FFP}) scanners, the excitation direction changes constantly [4]. If this change in direction exceeds the maximum mechanical rotation speed of the particles, they are not able to align. As a result, the particle signal will drop. In this work, we present a new device that is able to generate {FFP} and {FFL} field sequences while applying different possible offset fields.