The measurement of the forces at play in cell/cell adhesion uses a cell monolayer plated onto two-dimensional substrate like arrays of elastomeric microfabricated pillars. Unfortunately, the few attempts that have been done in this direction do not mimic the extracellular environment and lack knowledge on the correlation between the various types of cellular adhesions. Here, the authors suggest using a new experimental setup that more accurately simulates the three-dimensional (3D) environment of cells in tissues, using stretchable hexagonal monocellular 3D structures. The present article shows a way of fabricating these hexagonal biosensors, which are open structures made of biocompatible elastomeric polydimethylsiloxane (PDMS). The novelty of the whole fabrication process of these 3D PDMS structures consists in the use of a sacrificial silicon mold. An original mechanical PDMS planarization process is proposed. This article also describes a strategy for a selective functionalization of the 3D structure sidewalls where the cells must adhere. (C) 2010 American Vacuum Society. [DOI: 10.1116/1.3511435]