Subthreshold-Operated Low-Voltage Organic Field-Effect Transistor for Ion-Sensing System of High Transduction Sensitivity

A combination of the ion-sensitive organic field-effect transistor (ISOFET) transducer with silicon chips can utilize the strengths of both technologies for developing ubiquitous sensor systems. For optimal design of such a system, the transduction sensitivity of the ISOFET needs to be maximized. In this article, OFETs of different subthreshold swing (SS) values are fabricated using a solution processed organic semiconductor and dielectric materials to experimentally prove the dependence of the transduction sensitivity on the SS. Further ion-sensing measurement results show that the OFET of small SS (∼80 mV/dec) realized by both large gate dielectric capacitance and significantly reduced subgate density of states at the channel can help to achieve similar sensitivity with that of the silicon FET but with two-order lower power consumption.