Application of magnetic arrangement of microbeads for CMOS biosensor array sensitivity

To mitigate the increase in national medical expenses due to the aging population, we are currently researching and developing biosensors using complementary metal oxide semiconductor (CMOS) integrated circuits, which is one of the basic technologies in preventive medicine. Recently, we have realized a biosensor with the redox-potential detection using an extended gate that applies enzyme-immobilized microbeads. In the current research, to improve the sensor sensitivity, we try to arrange each microbead on each channel in the sensor array. To apply the microbead-arrangement method using magnetic field, we developed a magnetic modulator that magnetically attracts the beads to predetermined positions using a novel fabrication method for implementation on a CMOS sensor array. Next, the magnetic modulator was implemented on the CMOS sensor array, and we confirmed that the sensor and the magnetic modulator functions were satisfactory. Finally, the application of microbead arrangement using magnetic field to bioreaction revealed that the behavior of the reaction that occurred on the surface of the microbead reflected the amount of change in the potential in the neighboring channels. From this result, we discovered the possibility of improving the biosensor sensitivity by increasing the arrangement accuracy of the microbeads.