A biochip based on magnetoresistive sensors

The signal response of Bangs Laboratories magnetic markers with a mean diameter of 0.86 /spl mu/m on a spiral-shaped giant magnetoresistance sensor with a diameter of 70 /spl mu/m is investigated. The data show a linear dependence of the sensor signal on the surface coverage of the magnetic markers. The detection limit is reached at a coverage of about 5%, which corresponds to about 200 markers distributed across the surface of the sensor. The corresponding molecular binding of the analyte DNA and the magnetic markers show good selectivity and sensitivity.