Robust Radical-Mediated Electrical Enzyme Assay (REEA) Cartridge FET Sensor toward Practical Applications

Field-effect transistor (FET)-based biosensors are promising tools for early infectious-disease detection; however, their real-world deployment is limited by the Debye screening length, low signal strength, and the need for hours-long precalibration to correct device-to-device variation. Here, we present a radical-mediated electrical enzymatic assay (REEA)-integrated remote-gate FET (RGFET) biosensing platform that overcomes these constraints. The repurposed REEA mechanism enables detection of analytes far exceeding the Debye screening length and provides a 10- to 15-fold signal amplification (up to ∼150 mV dec^-1) compared with traditional FET biosensors. Coupled with a miniaturized standard cartridge design, REEA RGFET further demonstrates intrinsic self-compensation for variations in initial device responses, thereby providing a cornerstone for eliminating hours-long precalibration in traditional FET biosensors. Using this platform, we achieve attomol-level detection of mouse immunoglobulin G (IgG) without any precalibration, assisted by a deep-learning-based analysis framework. The system further demonstrates versatility through the detection of Staphylococcus aureus with performance comparable to conventional ELISA under identical assay conditions. Overall, the REEA FET cartridge system provides a sensitive and cost-effective pathway toward practical biosensing for infectious pathogen detection.