Sample-to-Answer Serum Diagnostics System-on-Chip.

Integrating multiple bioanalytical functions onto a single chip for point-of-care protein detection remains challenging. Here, we introduce a biological detection system-on-chip (BDSoC) that merges the purification capabilities of microfluidic chips with the detection sensitivity of carbon nanotube (CNT) field-effect transistor (FET) biosensors, achieving ultrasensitive analysis of trace protein biomarkers in complex samples. The BDSoC device allows direct and precise detection of tumor biomarkers in undiluted serum across an exceptionally low concentration range from 2 fg/mL to 1 pg/mL and correctly classified all 24 clinical serum samples tested in this study, corresponding to an observed diagnostic accuracy of 100% in this preliminary cohort. The platform is highly scalable, allowing for the future integration of biosensor arrays for multiplexing, advanced fluidic control, and versatile sample processing modules. This work marks a significant advance toward the ultimate vision of the "single-drop blood test" SoC, accelerating the practical deployment of FET biosensors and their evolution in point-of-care diagnostic technologies.