#BioE301C

Tap water from one of Stanford off-campus housing facilities was sampled. We did not observe any living creatures in the limit of the microscope magnification. The vesicle-like spheres are bubbles. We were incredible relieved to find that there are not observeable living organisms in tap water, at least with the resolution at which we were observing the tap water. This indicates that, at least on a cursory level, Stanford tap water seems to be safe to drink, although future work is required to confirm this hypothesis generated from our preliminary exploratory study.

Calculation of Scale Bar

The Foldscope was calibrated with a size scale in a manner similar to that described by our wonderful teaching assistant, Xinzhi Zou, in her Foldscope #BioE301C post from last year. In this approach, we draw two lines with a 1mm distance between them using a ruler. We take a picture of these two lines using the phone camera attached to the Foldscope. Finally, we appended a line going between these two lines at one-tenth of the length of the 1mm line to the image of interest, giving us a 100 micron scale bar.

Marija Pavlovic (marijavp), Peter Washington (peter100), Kasra Naftchi-Ardebili (knaftchi)