Biosensor G Reiss et al Univ of Bielefeld

Bio-sensor G. Reiss, et al. Univ. of Bielefeld Magnetic wireless actuator for medical applications K. Ishiyama, et al. Research Institute of Electrical Communication, Tohoku University Lecture 6

Special applications : - Bio-Chip R H Vertical magnetic field induces dipol field of bead Detection by GMR / TMR Sensor Signal prop. Number of Beads Increased sensitivity by lock-in technique, uncovered references, layout-Optimization possible: single molecule detection

Detection: Magnetoresistive biochip sensor 1) Immobilisation of target molecules Fixed DNA single strand XMR Sensor. Haftschicht Si- Substrate 3) Hybridisation with beads and detection with XMR sensor magnetic bead, coated with Streptavidin, binds to a selected molecule S XMR sensor detects stray field 2) Hybridisation of the probe molecules hybridized DNA Biotin N IEEE Trans. Magn. , (2002), ICM’ 03 • GMR (Giant Magneto. Resistance) • TMR (Tunnel Magneto. Resistance) detection of single beads / molecules

Special applications Design Characteristic 0° 90° GMR 0° 90° 22 20 Iunten Ioben 18 TMR-Amplitude in % Uunten Tunnelelement 16 14 12 10 8 6 4 2 Uoben 0 -50 -40 -30 -20 -10 0 10 Feld in Oe 20 30 40 50

DC-measurements with Bangs 0. 8 µm-beads Ref 1 - Sensor 3 Ref 1 - Ref 2 mit beads ohne beads Sensor coverage Signal 1) 5 % 2) 6 % 3) 20 % 4) 23 % 5) 40 % 77 µV 102 µV 267 µV 284 µV 557 µV

DC-measurements with Bangs 0. 8 µm-beads J. Schotter, P. B. Kamp, A. Becker, A. Pühler, D. Brinkmann, W. Schepper, H. Brückl, G. Reiss: A Biochip based on Magnetoresistive Sensors, IEEE Trans. Magnet. , 2002

Detection: TMR sensor TMR = Tunneling Magneto. Resistance T=10 K Ni. Fe sense layer T=300 K Al 2 O 3 Co. Fe hard magnetic layer Mn. Ir 5 nm 50 µm TMR Amplitude (%) TMR Biochip Sensor: 1. 6 DC-measurement, Bangs 0. 8 µm Beads parallel Bias-Field of -6. 4 Oe 1. 4 1. 2 1. 0 ~5 % coverage 0. 8 0. 6 0. 4 0. 2 0. 0 -100 -80 -60 -40 -20 0 20 40 60 80 100 perpendicular field (Oe) 2 x 2 µm 2 elements

Advantages of MAGNETIC micro-machine • Wireless operation • Simple structure Flying machine • Ways to supply energy – F = M (d. H/dx) → T = M H sin q – Magnetostriction – V = df/dt K. I. Arai, W. Sugawara, K. Ishiyama, T. Honda, M. Yamaguchi, “Fabrication of Small Flying Machines Using Magnetic Thin Films, ” IEEE Trans. Mag. , vol. 31, No. 6, pp. 3758 -3760 (1995).