This invention is a method of selectively functionalizing indentations (such as wells or channels in microfluidic systems) or protrusions on a substrate such that, for example, cells selectively bind to the indentations or the protrusions. The ability to control the placement of cells on a surface is useful in making arrays of cells, which in turn make possible analytical systems for the detection of toxic substances, systems for high throughput screening for drug discovery and new methods for the study of cellular function and metabolism of single cells. The novel method takes advantage of the observation that certain fluids (those with an advancing angle greater than 90 degrees) do not enter recesses in a substrate when the fluid is applied to the substrate. Other fluids do enter the recesses (i.e., those with advancing angles less than 90 degrees). Substances dissolved or suspended in the fluids, for example, cytophilic or cytophobic substances, then coat the surface in predetermined ways. The method lends itself to automation.