Detection of Stress Hormone with Semiconducting Single-Walled Carbon Nanotube-Based Field-Effect Transistors

Non-invasive detection and quantification of the stress hormone cortisol not only provide the assessment of stress level but also enable close monitoring of mental and physical health. In this work, we report two types of field-effect transistors (FETs) based on semiconducting single-walled carbon nanotubes (sc-SWCNTs) as selective cortisol sensors. In one FET device configuration cortisol antibody is directly attached to sc-SWCNTs, the other one is using gold nanoparticles (Au NPs) as linkers in between antibody and sc-SWCNTs to enhance the device conductance. We fabricated and characterized both device configurations to investigate how the nanomaterial interface to cortisol antibody influences the biosensor performance. We tested the sensors in artificial sweat and compared these two types of sensors in terms of limit of detection and sensitivity, and the results indicate that direct binding between antibody and sc-SWCNTs yields better biosensor characteristics.