We are developing the methodology to build hybrid biological/non-biological systems to create new information technology devices. This presentation will focus, from a bioengineering standpoint, the steps necessary to build such a device and some of the possible functions of these devices. We are using self-assembled monolayers (SAMs) to control the intrinsic and geometric properties of surfaces in contact with biological systems. The use of surface modification techniques allows us to tailor the interface between biological/nonbiological materials independent of the bulk composition of the nonbiological material. The ability to control the surface composition of the in vitro system as well as controlling other variables, such as growth media and cell preparation, all play important roles in creating a defined system for devise operation. This defined system has been used as a test-bed to evaluate surface coatings for neuronal interactions with electronic materials. We have used the geometric control of the surface composition afforded us by SAMs to create in vitro circuits of mammalian neurons. We have also recorded the electrophysiological signals produced by neurons on the patterned SAMs in response to stimuli. The surfaces have been characterized by X-ray photoelectron spectroscopy (XPS), imaging XPS and contact angle measurements and we have related the intrinsic properties of the surface and the proteins deposited by the cells to cellular development. We are using what we learn for a more fundamental understanding of cellular development and also to create sensors using living neurons as the sensor element. The continuing development of this technology will be discussed, our latest results, as well as the implications and applications for (a) biosensor fabrication, (b) neuronal circuit design, and (c) biological computation.