AC Electrothermal Flow-Enhanced, Label-Free Immunosensor for Rapid Electrochemical Sensing

We report a label-free immunosensor employing AC electrothermal flow- (ACEF-) induced mixing for rapid electrochemical measurements of protein biomarkers. Compared with conventional immunoassays that require long (> 1 hr) incubation periods, ACEF-induced mixing significantly reduces the time required for immunocomplex formation while also enhancing the detection sensitivity. Numerical simulations and experimental studies were performed to validate the ACEF mixing approach, and optimize the ACEF operating parameters. Through cyclic voltammetry and fluorescence imaging, we show that ACEF mixing enhances antigen-antibody binding resulting in improved detection sensitivity compared with incubation- based immunocomplex formation. For proof of concept, this immunosensor was used for quantitative measurements of Plasmodium falciparum histidine-rich protein 2 (PfHRP2), a biomarker for malaria infection, in buffer samples, which could be detected from 1 ng/mL - 10,000 ng/mL in < 10 min with excellent specificity.