A novel surface tension coefficient measurement method based on microposts array microfluidic chip

A novel surface tension measurement method based on microposts array microfluidic chip is presented and the fabrication process is studied. When the surface tension balance was broken due to evaporation, the tips of the microposts array submerged in aqueous solvent were pulled as vertical micro-cantilever at the liquid-air interface and displaced. In micro- or nanometers scale, the surface area to volume ratio becomes higher comparably, which means that the surface tension is dominant. The surface tension can be calculated by measuring microposts deformation. Microposts array was fabricated by templating the PDMS (poly-dimethylsiloxane) in the pores of polycarbonate track-etched (PCTE) membranes and filling the membrane pores by capillarity. Subsequently microposts were released by dissolving the template in an organic solvent and bond with micro-chamber collecting with micro-channel. By choosing appropriate membranes, different lengths and diameters of the microposts and the densities of the microposts arrays can be fabricated. The experiment result shows that the surface tension measurement method based on microposts array microfluidic chip is effective and the resolution can reach nN/μm.