PHD THESIS IN PHYSICS


On-chip manipulation and positioning of biomolecules with magnetic beads

written by
Michael Panhorst
born 3rd December 1974
in Bielefeld, Germany

Department of physics
Bielefeld University

July 2005

Preface

Publications

Conferences

Contents

Basics

• Biomolecules
  • Biotin
  • Avidin
  • Streptavidin
  • Ligand-Receptor bonds
• Functionalised magnetic markers
• Magnetic fields generated by conducting lines
• Computer-simulations of the magnetic fields
• Magnetic Tunnel Junctions
  • Tunneling effect
  • Tunnel Magneto Resistance
  • Exchange Bias

Preparation and analytical tools

• Sputtering thin films
• Ion beam milling
• Optical lithography
• E-beam lithography
• Auger electron spectroscopy
• Alternating Gradient Magnetometer
• Optical microscope with a CCD-Camera system

On-chip manipulation of magnetic markers with
conducting lines

• Basic sample preparation
• Problems during the measurements
• Examples for on-chip manipulation with magnetic markers
  • Current through a straight line
  • Trapping markers in a ring
  • Manipulation using electric fields
  • Transportation and positioning of magnetic markers
• Discussion

Bond-Force measurements

• Sulfur-gold bond
  • Results and Discussion
• Sample preparation for ligand-receptor bonds
• Surface preparation
• Selection of suitable magnetic markers
• Bond enthalpy of all involved bonds
• Results
• Discussion

Exact positioning of single magnetic particles

• Development of the lithographic design
• Specialities regarding the measurement conditions
• Results and discussion

A single magnetic particle on a TMR sensor

• Development of the TMR-Stack
  • Results and discussion
• Sample preparation
• Results
• Discussion

Summary and Outlook

List of Figures

Bibliography

Acknowledgements

About this document ...