An integrated microfluidic system with field-effect-transistor-based biosensors for automatic highly-sensitive C-reactive protein measurement

Rapid and accurate diagnosis of C-reactive protein (CRP) is crucial for preventing cardiovascular diseases because it is a well-known biomarker for evaluating risks of cardiovascular diseases. Our previous work has shown that a microfluidic system equipped with a field-effect-transistor (FET)-based biosensor could detect CRP in 0.1X PBS and provided a limit of detection (LOD) of 26 pM CRP without gate bias. To improve the LOD, a new microfluidic device with a new methodology for measuring FET-based biosensors is presented in this study. Not only can the proposed system work in a solution with a physiological salt concentration but it also detects CRP with ultra-high sensitivity in an automatic fashion. This is the first time that a FET-based biosensor can effectively and automatically detect CRP in a physiological salt concentration without decreasing the sensitivity. The LOD of CRP using aptamer-immobilized AlGaN/GaN high-electron-mobility transistors (HEMTs) was experimentally found to be 1fM, demonstrating the superior performance of this new technique. It may be used as a point-of-care device for CRP detection in the near future.