1Department of Physics and 2Department of Biology, University of Bielefeld, Universitätsstr. 25, D-33615 Bielefeld, Germany
e-mail: schotter@physik.uni-bielefeld.de
| Jörg Schotter1, Hubert Brückl1, Günter Reiss1, P. B. Kamp2, Anke Becker2, and Alfred Pühler2
1Department of Physics and 2Department of Biology, University of Bielefeld, Universitätsstr. 25, D-33615 Bielefeld, Germany e-mail: schotter@physik.uni-bielefeld.de |
|
Compared to the established fluorescent labeling method, the use of magnetic markers in biochip sensors has important advantages with respect to the detection of biomolecules at low concentrations [1,2]. The magnetic markers are commercially available superparamagnetic microspheres. We demonstrate the applicability and functionality of both Giant Magnetoresistance (GMR) and Tunnel Magnetoresistance (TMR) sensors for detecting magnetic markers. The GMR-sensors consist of patterned Cu/NiFe multilayers in the second antiferromagnetic maximum, whose resistance vs. field dependencies can be tailored for large sensitivity (up to 3%/Oe). Initial experiments with TMR sensors take advantage of the larger signal amplitude of around 40 % and corresponding sensitivity of 12 %/Oe. The measured signals for the detection of DNA-fragments show that the magnetic biosensors are more sensitive than current fluorescent detection units.
