An Optimal Two-Mixer Dilution Engine with Digital Microfluidics for Low-Power Applications

Digital microfluidic biochips are now being widely used for implementing a variety of complex biochemical laboratory assays (bio-protocols) on a tiny device. These devices provide fast and accurate test results with very little reactant usage and they consume extremely low power. Dilution of a fluid is one of the basic steps in sample preparation that is required in the automation of biochemical assays. In this work, we design a two-mixer dilution engine for sample preparation that can produce a stream of droplets of a target fluid with a given concentration factor CF. We show that the proposed scheduling scheme is time-optimal and it requires a constant number of on-chip storage depending on the accuracy level of CF. A biochip architecture with two (1:1) microfluidic mixer modules that implements the engine is also shown. Simulation results on the average rate of droplet emission, reactant usage, and electrode actuation energy have been reported for several examples.