Development of a CMOS Dielectrophoresis and Microbead-Based Capacitive Immunosensor Array

Dielectrophoresis (DEP) is a noncontact manipulation method used for driving biological cells and dielectric microparticles to desired locations, facilitating the sorting and detection of multiple targets with a driving voltage compatible with integrated-circuit processes. This work presents a fully integrated platform in a complementary metal-oxide–semiconductor (CMOS) process combining DEP and capacitive sensing for immunodetection. Microbeads containing the targets to be detected are driven toward probe-immobilized electrode surfaces using DEP. Upon specific binding, this results in a capacitive change due to the presence of the remaining microbeads. The design of DEP driving electrodes was thoroughly analyzed using finite-element simulation techniques. Microbeads immobilized with antimouse immunoglobulin (IgG) were successfully driven to the
$20\times 20~\mu $
m sensing electrodes of the
$16\times 32$
array by applying a peak-to-peak voltage of 3 V at 10 MHz. The measured results demonstrated an output sensitivity of 2.6 mV/fF, with a minimum detectable capacitance of 63 aF.