Authors: T. Yamada, K. Sakai
Affilation: Institute of Industrial Science, the University of Tokyo, Japan
Pages: 283 - 286
Keywords: micro droplet, liquid properties, drop oscillation
The application of inkjet printing to industrial processes such as microfabrication, bioengineering is attracting great attention these days. These processes involve large shear deformation of micro-scale and complex liquid, therefore, the importance to measure properties of microscopic liquid in high-shear flow is increasing. However, conventional measurement techniques such as viscometers and rheometers can only deal with millimeter liquid. We measured the liquid properties under large shear deformation, by observing an oscillation of 10-micron droplets. The oscillation is induced by a head-on collision of droplets emitted by inkjet. Since the typical Reynolds number is smaller than 100, the motion of droplets can be observed with high reproducibility by stroboscopic method. We examined the oscillation of several kinds of liquids. For water, silicone oils and glycerol solutions, the experimental values of liquid properties almost agree with the literature values. For associated liquid such as ethylene glycol, the experiment suggested smaller viscosity. This can be attributed to the slow viscous relaxation of associated liquids due to the re-combination dynamics of the H-bond network. In addition, for surfactant solution droplets, we found that the waveform is distorted, which can be attributed to the surface absorption of surfactant molecules.