Detection of chemical species in gas or vapor phases is a rapidly growing field. Detection can be used as a warning system for chemical and biological threats, as well as to monitor air quality concerns. These sensors generally fall into two categories: sensing semiconductors and sensing gates. Sensing semiconductors have poor selectivity, while sensing gates have poor sensitivity. Additionally, state-of-the-art chemical sensors are expensive and material-dependent. They also require specific conditions for proper operation.
The dual gate field effect transistor (DG-FET) combines sensing semiconductor and sensing gate technologies to provide both high chemical sensitivity and high selectivity. The top gate is functionalized for sensitivity to ammonia and interacts with the analyte. The bottom gate drives the transistor into saturation to enhance sensitivity. The DG-FET chemical sensor can be easily tailored to detect a wide range of chemicals by changing the functional layer alone. Additionally, this sensor is highly conductive and can be used with off-the-shelf electronics, which reduces manufacturing and circuitry costs.