Understanding the signal amplification in dual-gate FET-based biosensors

Field-effect transistor (FET)-based sensors allow rapid, label-free electrical detection of chemical and biological species and are easy to use. Dual-gate FET-based biosensors enable sensitive detection with high intensity signal by their distinctive structure based on a combination of solid and liquid gates. However, the underlying mechanism of signal amplification to explain the experimental results has not been well explained with theoretical analysis. In this work, a theoretical approach based on device physics is used to interpret the signal enhancement in dual-gate FET-based biosensors. The analysis is verified with a simulation method for pH sensors based on a well-established commercialized semiconductor 3D technology computer-aided design simulation. The pH sensing parameters are comprehensively investigated as a function of the electrical characteristics of dual-gate FETs: the voltage, current, and normalized current signals are directly correlated with capacitive coupling, transconductance, and subthreshold swing, respectively. Our theoretical analysis provides design guidelines for sensitive dual-gate FET-based biosensors.