DRAFT--DRAFT--DRAFT--DRAFT--DRAFT--DRAFT--DRAFT--DRAFT--DRAFT--DRAFT Circuit Development using Biological Components: Principles, Models and Experimental Feasibility

1 Abstract Today most VLSI circuits are built in silicon using CMOS transistors. Developments in design automation and process fabrication have resulted in the progressive increase of the number of transistors per chip and decrease in the size of the transistors. But transistor designers are fast approaching fundamental physical barriers to further size reduction. Thus engineers are looking at alternate technologies such as nano-devices and bio-circuits for next-generation circuits. In our research, we concentrate on the development of biocircuits and their applications. Our eventual goal is the design and simulation of complete systems integrating bio-circuits and VLSI technology appropriately. Biocircuits are circuits developed in-vivo or in-vitro, using DNA and proteins. A biological process such as glycolysis or bioluminescence can be viewed as a genetic regulatory circuit, a complex set of bio-chemical reactions regulating the behavior of genes, operons, DNA, RNA and proteins. Similar to voltage in an electrical circuit, a genetic regulatory circuit produces an output protein in response to an input stimulus. We can engineer biocircuits to meet design specifications, using genetic engineering. Our aim is to build a library of in-vitro biocircuits representing the Boolean functions. The biocircuits from this library can be further cascaded to form larger circuits. In this paper, we review the feasibility of building bio-circuits. We discuss the construction of Boolean logic gates such as NOT, AND and OR and their verification by simulation. We also address important aspects such as cascading of the bio-circuits and practical implementation. In addition, we describe an algorithm “Box” that can help to control bio-circuit characteristics such as gain and switching behavior. This approach is similar to design space exploration in traditional VLSI, but takes into account biological knowledge obtained through experiments. We also provide insight into the robustness of bio-circuits in the presence of noise. This paper is intended to pave the pathway for electrical engineers to start exploring the field of bio-circuits.