Novel electrodes for precise and accurate droplet dispensing and splitting in digital microfluidics

Abstract

Digital microfluidics (DMF) is a versatile fluid handling tool that is widely used in the biochemical field. There are very high requirements for the volume of single droplet in many biochemical applications. Droplet dispensing and splitting are two main operations to generate a single droplet in DMF. Therefore, the generation of droplets with high volume precision and accuracy in the two droplet operations is one of the keys to the efficient application of DMF in biochemical analysis. We have developed a novel droplet dispensing and splitting scheme where electrode geometry is optimized. The liquid column can contract in a regular shape, which keep the neck shape uniform and stable, and the position of pinch-off point was fixed; meanwhile, the liquid tail is eliminated before pinching off, so that the precision and accuracy of droplet volume were greatly improved. The increase in the radius of the cutting electrodes elongated the droplet neck and increased the neck curvature at the pinch-off point, which further effectively improved the precision and accuracy of droplet volume. The optimized droplet splitting scheme can also be applied to the droplet splitting with unequal volume effectively.