Scientists at University of Illinois have reported a new method of monitoring cell behavior over a large optical resolution range (micrometers to millimeters) and at time scales from seconds to days. 
Known as Spatial Light Interference Microscopy (SLIM), the technique can resolve mass to one femtogram, and monitor the behavior of single living cells within a larger collection.
Gabriel Popescu, the lead author of the study, says: “By using a fluorescence reporter in conjunction with this novel optical technique, we were also able to differentiate how the cells regulate their growth in different stages of their lifecycle. Aside from the basic science interest, this technology could have broader implications in understanding the effects of cancer treatments and other forms of therapy on the fundamental process of cell growth.”
Learn more here: Optics used to track single cell’s growth …
Abstract in PNAS: Optical measurement of cycle-dependent cell growth