Single-walled carbon nanotube-based Schottky transistor for the detection of human immunodeficiency virus-1 antibodies in human serum.

Label-free electrical biosensors based on field-effect transistors offer considerable potential for rapid biomolecular detection, yet their performance under physiologically relevant ionic-strength conditions remains fundamentally constrained by Debye screening. Here, we present a single-walled carbon nanotube (SWNT)-Au Schottky transistor that addresses this limitation by exploiting interfacial Schottky barrier modulation rather than conventional field-effect gating. Uniform SWNT thin films prepared by the Langmuir-Blodgett (LB) technique enabled reproducible device fabrication with well-defined electrical characteristics. The proposed biosensor enabled real-time, label-free, and concentration-dependent detection of human immunodeficiency virus type 1 (HIV-1) antibodies in newborn calf serum under physiologically relevant ionic-strength conditions (∼150 mM). Comprehensive analytical validation demonstrated reliable quantitative performance, high device-to-device reproducibility, and robust sensing across different ionic-strength conditions. Collectively, these results establish Schottky barrier modulation as an effective electrical transduction strategy for label-free biosensing in complex biological media and provide a versatile platform for future clinical diagnostics and environmental sensing applications.