An in vitro neural network can provide a model to investigate the signaling processes that regulate the body functions. Using polydimethylsiloxane (PDMS) multilayer micro-structures to construct a neural network, the bonding between the layers can be improved by modulation of the curing ratio. In this study, we found that as the curing ratio increased from 10:1 to 10:4, the contact angle decreased from 111.69 degrees to 102.08 degrees and the surface energy and roughness increased. For adhesion and proliferation, the hippocampal primary neural cells preferred a PDMS surface with a 10:1 curing ratio to other surfaces. In addition, 3D PDMS micro-pyramid array allows the primary hippocampal neuron to pattern a network without any surface treatment and the network was verified by immunocytochemistry. These results may suggest the optimum PDMS curing ratio to apply in constructing a cell device for in vitro neural network formation as well as the potential of 3D structure fabrication which allows us to construct neural network without any surface treatment. (C) 2009 Elsevier B.V. All rights reserved.