Dielectric‐Modulated Biosensing with Ultrahigh‐Frequency‐Operated Graphene Field‐Effect Transistors
Xiaoyan Zhang, Tingxian Liu, Aimee L. Boyle, Azadeh Bahreman, Lei Bao, Qiushi Jing, Honglei Xue, Roxanne E. Kieltyka, Alexander Kros, Grégory F. Schneider, Wangyang Fu
Abstract
Owing to their excellent electrical properties and chemical stability, graphene field-effect transistors (Gr-FET) are extensively studied for biosensing applications. However, hinging on surface interactions of charged biomolecules, the sensitivity of Gr-FET is hampered by ionic screening under physiological conditions with high salt concentrations up to frequencies as high as MHz. Here, an electrolyte-gated Gr-FET in reflectometry mode at ultrahigh frequencies (UHF, around 2 GHz), where the ionic screening is fully cancelled and the dielectric sensitivity of the device allows the Gr-FET to directly function in high-salt solutions, is configured. Strikingly, by simultaneous characterization using electrolyte gating and UHF reflectometry, the developed graphene biosensors offer unprecedented capability for real-time monitoring of dielectric-specified biomolecular/cell interactions/activities, with superior limit of detection compared to that of previously reported nanoscale high-frequency sensors. These achievements highlight the unique potential of ultrahigh-frequency operation for unblocking the true potential of graphene biosensors for point-of-care diagnostic.