A low cost and palm-size analyzer for rapid and sensitive protein detection by AC electrokinetics capacitive sensing

Specific detection of protein biomarkers has a wide range of applications in areas such as medical science, diagnostics, and pharmacology. Quantitative detection of protein biomarkers in biological media, such as serum, is critically important in detecting disease or physiological malfunction, or tracking disease progression. Among various detection methods, electrical detection is particularly well suited for point-of-care (POC) specific protein detection, being of low cost, light weight and small form factor. A portable system for sensitive and quantitative detection of protein biomarkers will be highly valuable in controlling and preventing diseases outbreaks. Recently, an alternating current electrokinetic (ACEK) capacitive sensing method has been reported to demonstrate very promising performance on rapid and sensitive detection of specific protein from serum. In this work, a low cost and portable analyzer with good accuracy is developed to use with ACEK capacitive sensing to produce a true POC technology. The development of a board-level capacitance readout system is presented, as well as the adaption of the protocol for use with ACEK capacitive sensing. Results showed that the developed system could achieve a limit of detection of 10 ng/mL, comparable to a sophisticated benchtop instrument. With its small size and light-weight similar to a smart phone, the developed system is ready to be applicable to POC diagnostics. Further, the readout system can be readily expanded for multichannel monitoring and telecommunication capabilities.