solutions, we added standard solutions of glucose to the substrate
zone with 2 L per zone and detection solutions of glucose to the
detection zone with 5 L per zone. The left branch was blank and
a series of concentrations of glucose solutions were spotted on the
right six branches (as shown in Scheme 2). The test sheet was then
allowed to be dried at room temperature for 5 min. Then the paperbased
device was dipped into the distilled water. When developing
reagent water goes from stem to a wider one, its frontline spreads
from the previous straight line to a semi-circle. Consequently, in
our design all branches start at the periphery of the same semicircle,
whose center is in the middle of the stem’s top.