Sensitive and specific point-of-care detection of pathogen infections by an AC electrokinetics-enhanced capacitive immunosensor

The past decades have witnessed rapidly growing demands for portable, low-cost bioassays with minimal complexity in manufacturing, operation and instrumentation that can provide reliable real-time information for clinical diagnosis. To address this need, an “AC electrokinetic (ACEK) capacitive sensing” method is developed that is capable of rapid, low cost and simple-to-operate specific assay for use with practical samples. The major innovation with this sensing technology is its ability to simultaneously generate ACEK effects in the fluid and to interrogate directly the sensor's interfacial capacitance. The AC signal will induce movement of proteins towards the electrode surface and accelerate the binding to immobilized probe molecules. The binding of protein is sensitively detected by monitoring the interfacial capacitance of electrode. Preliminary experiments from biological fluids yielded highly encouraging results, with limits of detection at 2.3 pg/mL measured by a benchtop instrument and around 5 pg/mL by a portable reader, which is on par with the best laboratory assay available and ours is a POC technology. This article presents the mechanisms, development and test results of this POC immunoassay.