Simplified Real-Time Organic Transistor Characterisation Schemes for Sensing Applications

We report two cost-efficient, low power consumption characterisation schemes for organic trans stors, designed for sensor applications. We demonstrate real-time multiparameter characterisation of organic transistors (carrier mobility and threshold voltage) using only signal generator, oscilloscope, and a current-to-voltage converter. In the absence of signal generator and oscilloscope, we used an organic transistor as the time-delay that controls the frequency of oscillations driven by a 555 timer IC. Characterisation required less than 200 mu W. In one mode of operation, 555 output displays very brief (<1 mu s) needle-like pulses spaced in time intervals that are inversely proportional to the transistor's drain current. This mode is intended to drive highly power-efficient, carrier-wave-free radio transmitters, which are the most promising technology for wireless sensor networks.