The ‘coffee ring effect’ is known as when a drop of spilt coffee dries up, the outermost edge of the dried drop is a little darker than the centre, forming a darker ‘ring’.
- This is caused by the outward drift of suspended coffee particles from the centre, causing a denser, darkened rim.
- Now, researchers from Indian Institute of Technology, Madras, have shown that after reaching the rim, as the drop dries, some of the particles undergo an inward drift too.
- This research has applications in agriculture, forensic science and even disease diagnosis. The present work has been published in the journal, Soft Matter.
