Shin-Hyun Kim, Tae Yong Lee and Sang Seok Lee
Article first published online: 24 MAR 2014 | DOI: 10.1002/smll.201470037
Osmocapsules are microfluidically created to provide a tool for direct measurement of osmotic pressure. As reported by S.-H. Kim and co-workers on page 1155, the osmocapsules enclose standard aqueous solution with an ultrathin polymeric membrane. When many distinct osmocapsules with all different osmolarities are dispersed in an unknown solution, the osmocapsules, subjected to positive osmotic pressure, selectively exhibit discernible buckling. In the image, only red and orange capsules buckle, whereas yellow and green do not. This enables the estimation of osmotic pressure of the medium, which is in a range between the osmotic pressures of aqueous cores of orange and yellow capsules.