Log-domain circuit models of chemical reactions

We exploit the detailed similarities between electronics and chemistry to develop efficient, scalable bipolar or subthreshold log-domain circuits that are dynamically equivalent to networks of chemical reactions. Our circuits can be used for transient and steady-state simulations, parameter estimations and sensitivity analyses of large-scale biochemical networks. They allow the topology, rate constants, inputs, outputs and initial conditions of the reaction network to be programmed. When reactants are present in low concentrations, random fluctuations in reaction rates become significant; we can also model such stochastic effects. We present experimental results from a proof-of-concept chip implemented in 0.18 mum CMOS technology.