Molecular transport at a cell membrane is an important signature of cellular metabolism and its response to extracellular environmental factors and intrinsic genetic expression of the cell. We have developed a BioMEMS sensor array by which oxygen transport in the vicinity of a single cell or a small clump of cells can be monitored and a simple mathematical theory by which the concentration data obtained from the Pt microring electrode can be translated into oxygen consumption by the cell(s). This device was used to monitor oxygen concentration transients at clumps of cells and single cells using a novel amperometric pulsing protocol that minimizes oxygen consumption by the electrode itself that could otherwise interfere with cellular oxygen uptake. As the number of cells was sequentially increased from one to five inside the microring, a step-wise decrease of oxygen concentration in the surrounding medium was recorded, which is an indication of increased oxygen consumption by the increasing number of cells. Decreased oxygen consumption of a single cell under the effect of ouabain and increased oxygen consumption of a cell after administration of FCCP were observed that further validates the data obtained using the reported BioMEMS approach.