Measurements of surface tension of organic solvents using a simple microfabricated chip

Measurement of the surface tension of organic solvents using a simple microfabricated chip was developed based on the principle of differential capillary rise. The theory, design, fabrication, and characterization of the chip were described. A two-step etching technique was used to fabricate a number of microchannels with different dimensions on the glass substrate. Capillarity was used to introduce liquid samples, which requires no power supply or actuator to be applied in the experiment. Liquid in different microchannels generated capillary rise with different heights, by which surface tension maybe calculated. Seven common organic solvents, ethanol, acetone, acetonitrile, dichloromethane, hexane, methanol, and toluene, were tested at room temperature. The surface tension of ethanol at different temperatures was measured over the range of 5-45 degrees C. Relative standard deviation for seven replicate measurements at each temperature is 0.20-0.74%. The results showed good reproducibility and acceptable precision compared with traditional methods. Very low reagent consumptions and short analysis time were achieved using this simple method.