Advanced Field-Effect Sensors

Sensors based on the field-effect principle have been used for more than fifty years in a variety of applications ranging from bio-chemical sensing to radiation detection or environmental parameter monitoring. The basic working principle of field-effect sensors is the same as that of field-effect transistors (FETs) in which the conductance between two electrodes (source and drain) is controlled by the electric field generated by a gate. In these sensors, the gate often includes or is connected to the sensing element. Field-effect biochemical sensors have found increasing applications for pH and molecular or DNA sensing since the proposal of the ion-sensitive field-effect transistor (ISFET) by Bergveld in 1970. Field-effect devices have been extensively exploited for gas sensing, and photo-activated FETs (Photo-FETs) are actively progressing as chemical and gas detectors. Both junction (JFET) and metal–oxide–semiconductor (MOSFET) FETs are widely used as photodetectors and ionizing radiation detectors or dosimeters in radioprotection, radiotherapy, medicine, and dentistry. Furthermore, FETs enable sensitive temperature sensors and piezoelectric strain gauges. In the past three decades, the advent of nanostructured materials, either one-dimensional (1D) or two-dimensional (2D), has created opportunities to integrate new sensing materials or to develop innovative architectures in field-effect-based sensors. The optimization of existing devices, the experimentation of new field-effect structures and fabrication techniques, and the design of novel electronic systems for signal amplification and processing are currently underway. A great advantage of field-effect sensors is that they provide intrinsic signal amplification and can be integrated with the electronics needed for the sensor’s signal processing on the same semiconductor chip. Moreover, field-effect sensors feature a high sensitivity, low cost, and miniaturization. Field-effect-based sensing offers several challenges arising from the highly interdisciplinary nature of the applications in which knowledge of material science, surface chemistry and physics, biomolecular kinetics, electronic engineering, etc., is required. This Special Issue summarizes the recent trends in the research on the fabrication, design, understanding, simulation, and utilization of field-effect sensors, with particular attention for biological and chemical sensing.