Digital microfluidic biochip design for protein crystallization

Proteins crystallization is a commonly used technique for protein analysis. It predicts the three-dimensional (3D) arrangement of the constituent amino acids, which indicates the specific biological function of a protein. Protein crystallization experiments are typically carried out in well-plates; as a result, these experiments are slow, expensive, and errors are likely due to the need for repeated human intervention. Recently, droplet-based “digital” microfluidics has been used for executing protein assays on a chip. Protein samples are enclosed in droplets, which are manipulated using the principle of electrowetting-on--dielectric. Digital microfluidics offers a high degree of automation, and it significantly reduces the volumes of proteins required for crystallization. We present the design of a multi-well plate microfluidic biochip for protein crystallization, which can transfer protein samples, prepare candidate solutions, and carry out crystallization automatically. To reduce the manufacturing cost of such devices, we present an efficient algorithm to generate a pin-assignment plan for the proposed design. The resulting biochip enables control of a large number of on-chip electrodes using only a small number of pins.