Carbon nanotube (CNT) field-effect transistor (FET)-based biosensors have shown great potential for ultrasensitive biomarker detection, but challenges remain, which include unsatisfactory sensitivity, difficulty in stable functionalization, incompatibility with scalable fabrication, and nonuniform performance. Here, we describe ultrasensitive, label-free, and stable FET biosensors built on polymer-sorted high-purity semiconducting CNT films with wafer-scale fabrication and high uniformity. With a floating gate (FG) structure using an ultrathin Y2O3 high-κ dielectric layer, the CNT FET biosensors show amplified response and improved sensitivity compared with those sensors without Y2O3, which is attributed to the chemical gate-coupling effect dominating the sensor response. The CNT FG-FETs are modified to selectively detect specific disease biomarkers, namely, DNA sequences and microvesicles, with theoretical record detection limits as low as 60 aM and 6 particles/mL, respectively. Furthermore, the biosensors exhibit highly uniform performance over the 4 in. wafer as well as superior bias stress stability. The FG CNT FET biosensors could be extended as a universal biosensor platform for the ultrasensitive detection of multiple biological molecules and applied in highly integrated and multiplexed all CNT-FET-based sensor architectures.
Keywords: DNA; biosensor; carbon nanotubes; extracellular microvesicles; field-effect transistors.