Sensitive gas sensor embedded in a vertical polymer space-charge-limited transistor

We report a very sensitive gas sensor embedded in a vertical polymer space-charge-limited transistor. The oxidizing and reducing gases act as electron dedoping and electron doping agents on the transistor active layer to change the potential distribution in the vertical channel and hence to change the output current density. With a 30-ppb detection limit to ammonia, the sensor can be used for non-invasive breath monitor in point-of-care applications. The integration of a sensitive gas sensor and a low-operation-voltage transistor in one single device also facilitates the development of low-cost and low-power-consumption sensor array.