High Aspect Ratio Fin-Ion Sensitive Field Effect Transistor: Compromises toward Better Electrochemical Biosensing

The development of next generation medicines demands more sensitive and reliable label-free sensing able to cope with increasing needs of multiplexing and shorter times to results. Field effect transistor-based biosensors emerge as one of the main possible technologies to cover the existing gap. The general trend for the sensors has been miniaturization with the expectation of improving sensitivity and response time but presenting issues with reproducibility and noise level. Here we propose a Fin-Field Effect Transistor (FinFET) with a high height to width aspect ratio for electrochemical biosensing solving the issue of nanosensors in terms of reproducibility and noise, while keeping the fast response time. We fabricated different devices and characterized their performance with their response to the pH changes that fitted to a Nernst-Poisson model. The experimental data were compared with simulations of devices with different aspect ratio, establishing an advantage in linearity and lower device resistance to provide higher current signals for the FinFETs with higher aspect ratio. In addition, these FinFETs promise the optimization of reliability and efficiency in terms of limits of detection for which the interplay of the size and geometry of the sensor with the diffusion of the analytes plays a pivotal role.