Abstract: A vertical cell pairing (VCP) system comprising: a substrate having a top surface; at least one micropit formed in the top surface of the substrate, the at least one micropit being sized to seat a cell; and at least one microtrap positioned adjacent the top surface of the substrate, the at least one microtrap comprising a body having a vertical slot, wherein the vertical slot has an opening and an exit, the vertical slot being sized to pass fluid therethrough but to prevent a cell from passing therethrough; wherein the at least one microtrap is disposed relative to the at least one micropit so that a cell seated in the at least one micropit is in cell-cell communication with a cell disposed at the opening of the vertical slot.