Microparticle detector for biosensor application

We report on the development of a high-sensitivity electrical biosensor that detects analyte molecules labelled by microparticles. Detection is, achieved by measuring electrochemical current changes occurring when bead-labelled analyte molecules get specifically bound to microelectrodes. We present measurements with transducers that bear microelectrode arrays with a large number of microelectrodes connected in parallel as well as single addressable microelectrodes. These measurements reveal the very sensitive detection of even one single microparticle. By using magnetic microbeads a magnetic force can be applied to the beads to remove them from the electrodes. When this force exceeds the specific binding force of the analyte molecule the bound microparticles are removed and a signal is produced. We assume that the transducer could also be used for the determination of specific binding forces. (C) 2002 Elsevier Science B.V. All rights reserved.