  In this paper, we apply dimensional analysis to study a diffusive molecular
communication system that uses diffusing enzymes in the propagation environment
to mitigate intersymbol interference. The enzymes bind to information molecules
and then degrade them so that they cannot interfere with the detection of
future transmissions at the receiver. We determine when it is accurate to
assume that the concentration of information molecules throughout the receiver
is constant and equal to that expected at the center of the receiver. We show
that a lower bound on the expected number of molecules observed at the receiver
can be arbitrarily scaled over the environmental parameters, and generalize how
the accuracy of the lower bound is qualitatively impacted by those parameters.
