Bio-inverter model and interface to digital hardware

Conventionally, VLSI circuits are built using CMOS transistors and the circuits are fabricated on silicon. But the looming crisis created by continually shrinking CMOS features sizes is pushing scientists to research alternate technologies for future generations of circuits. One active field of research is the development of bio-circuits. In this paper we discuss one such bio-circuit, the bio-inverter. This inverter is implemented using the switching mechanism observed in the phage lambda virus. This switching mechanism has been well documented in work by Ptashne and by Weiss. We have developed a model for such an inverter both in Matlab and also in VHDL-AMS. Our simulations show that the bio-inverter possesses good rise and fall time characteristics, switching threshold and gain, even though the gate switching time is approximately 10² seconds. We have also discussed the practical limitations of building bio-circuits and their applications as sensors for drug research.