A novel microfluidic chip based on an impedance-enhanced electrochemical immunoassay

Electrochemical immunoassays have been employed in clinical diagnostics for a considerable duration. The use of microspheres or microbeads as carriers for biomarkers serves as a foundational platform for biochemical testing. In conventional electrochemical immunoassays, constant potential instruments are predominantly utilized to measure current variations on the electrode surface, thereby achieving optimal sensitivity. However, the bio-modified electrode surface introduces complexities in cleaning, separation, and other applications. We present a novel microfluidic device based on an impedance-enhanced electrochemical immunoassay that introduces a continuous fluid quantitative platform that employs freely moving multiplex beads containing antigens bound to magnetic and dielectric micro/nanobeads, which are measured using an electrochemical impedance biosensor, all within a one-way microchannel of a microfluidic chip. This device utilizes antibody-coated magnetic beads and dielectric beads conjugated with detection antibodies for quantitative analysis in conjunction with portable electronic devices. Additionally, we have developed an innovative algorithm for microbead analysis based on the modeling of coplanar electrodes to detect viral proteins. This unique bead-based technology has been successfully integrated into a microfluidic chip and proved to have effectively detected COVID-19. The proposed device leverages bead-based technology and electrical impedance characteristics, offering substantial potential for integration with miniaturized electronic elements. This microfluidic device facilitates simple, rapid, efficient, portable, compact, and cost-effective high-throughput measurements, thereby enhancing clinical diagnostic capabilities for emerging infectious diseases.