Cinnamon oil microemulsion droplet morphology was visualized by transmission electron microscopy (TEM). Sample for TEM analysis was prepared by placing one drop CMF4 cinnamon oil microemulsion (negatively stained with phosphotungstic acid) onto a copper grid. Images were captured by a transmission electron microscope (Tecnai-10, Philips) supplied with a W-source and a working voltage of 80 kV.