Organic oscillator and adaptive amplifier circuits for chemical vapor sensing

Organic transistor based circuits that can be employed for chemical vapor sensing, are described. Such circuits have improved sensing characteristics in comparison with discrete transistor based sensors. Complementary ring oscillator based sensors have a stronger response to analytes such as octanol and allyl propionate compared to a single transistor. A fabrication process that combines organic semiconductor circuitry with Si is described. The design and advantages of adaptive differential amplifiers with high gain and feedback are described. Voltage gains of ∼20 allow the detection of weak odorant inputs and the adaptive feedback allows for improved background elimination.