Due to the small amounts of synthesized conjugated polymer material we measured the viscosity of polymer solutions using only a few microliters. We used the method developed by Srivastava and Burns where a solution is drawn into a microchannel by capillarity and its free surface is tracked in order to calculate its viscosity. We used a microfluidic glass capillary with a rectangular channel 200 µm wide and 20 µm high (Microslide 5002-050, Wale Apparatus). The capillaries were placed in a small chamber saturated with chlorobenzene vapor. Approximately 5-10 µL of conjugated polymer solution was pipetted onto an open end of the capillary. A camera was used to record the solution as it flowed into the microfluidic capillary. Using the procedure from Srivastava and Burns , we determined the position and velocity of the free surface over time and calculated the viscosity of the solution at low velocities using the following equation,