Figure 4. Effect of nitrogen gas intensity.

(a) Change of drain current (I_D) as a function of time in the LC-on-OFET sensory devices upon applying nitrogen gas flows to the LC surface, where the intensity of nitrogen gas flows was varied from 11 μl/s (0.7 sccm) to ~50 μl/s (3 sccm) but the applying time was fixed as 15 s: Inset shows the change of maximum (peak) I_D as a function of nitrogen gas flow intensity. (b) Change of delay time (left) and time constants (right) as a function of nitrogen gas flow intensity: The delay time is defined as the time (of the increasing I_D trend) to reach a maximum (peak) value even after stopping the nitrogen gas flows, while the rise/decay time constants were obtained by fitting with a single exponential equation (see the details in the experimental part). Note that the minus (−) sign in I_D was omitted to avoid crowding data display.