Multiple Dilution Sample Preparation Using Digital Microfluidic Biochips

Digital microfluidic (DMF) biochips offer a versatile platform for implementing several laboratory based biochemical protocols. These tiny chips can electrically control the dynamics of nanoliter volume of discrete fluid droplets on an electrode array with desired actuation patterns. One important step in biochemical sample preparation is dilution, where the objective is to prepare a fluid with a desired concentration factor. Bioassays implemented on DMF biochips may require several different concentration values of the same sample. In this paper, we propose a scheme in which a set of different target droplets (target concentration values ranged between 0% and 100%) can be produced using 0% concentration (buffer solution) and 100% concentration (sample/reagent), with an error bounded above by 1/2^(n+1) where concentration values are rounded-off by an n-bit binary fraction. Simulation results show that significant amount of savings in the number of mix-split steps and waste droplets can be achieved in comparison with the repeated use of existing single target based methods for generating multiple concentration factors.