  The performance of molecular communication is significantly impacted by the
reception process of the messenger molecules. The receptors' size and density,
however, have yet to be investigated. In this letter, we analyze the effect of
receptor density and size on the signal reception of an absorbing receiver with
receptors. The results show that, when the total receptor area is the same,
better hitting probability is achieved by using a higher number of relatively
small receptors. In addition, deploying receptors, which cover a small
percentage of the receiver surface, is able to create an effective
communication channel that has a detectable signal level.
