Speed improvement of a pathogenic micro-organism population detection with LAPS system by a magnetic bead separation and a pH detection

A magnetic bead based immobilization method and pH detection method is applied to the LAPS (light addressable potentiometric sensor) system to detect a pathogenic micro-organism population. Magnetic beads are very small, superparamagnetic particles (0.8/spl sim/5.0 /spl mu/m in diameter) that are able to sustain a magnetic domain under excitation and do not exhibit residual magnetization when the external field is removed. By using magnetic beads as an immobilization method, other bulky and complex method can be alternated. To verify the method, an urease labeled antisalmonella typhimurium antibody is used to detect a pathogenic micro-organism( S. typhimurium ) population by a bias voltage maximum slope detection.