Controllable Droplet Ejection of Multiple Reagents through Focused Acoustic Beams.

Acoustic droplet ejection (ADE) technology has revolutionized fluid handling with its contactless and fast fluid transfer. For precise droplet ejection and stable droplet coalescence at the target substrates for further detection, the input power of the ADE system needs to be adjusted. Currently, the existing power control method depends on scanning the source fluid wells one by one, which cannot afford precise and highly efficient droplet velocity adjustment, and the complicated operation caused by the repeated power evaluation processes for thousands of fluid transfers will waste much time. We propose a new method, which realizes the controllable ejection of multiple reagents by analyzing the effect of the product of kinematic viscosity and surface tension of the reagents on the droplet initial velocity. The experimental results obtained by ejecting dimethyl sulfoxide coincide well with the predicted results, and the relative error in the droplet initial velocity is mostly less than 8%. On the basis of the input power prediction method proposed in this paper, the ADE system is successfully constructed for continuous dispensing of polystyrene microspheres as cell surrogates, which provided an advanced liquid handling solution for research in biochemistry and other fields.

A review on acoustic droplet ejection technology and system.

The pace of change in chemical and biological research enabled by improved detection systems demands fundamental liquid handling and sample preparation changes. The acoustic droplet ejection (ADE)-based liquid handling method has the advantages of improving precision and data reproducibility, reducing costs, hands-on time, and eliminating waste. ADE gradually replaced traditional aspiration-and-dispense liquid-handling robots in applications such as synthetic biology, genotyping, personalized medicine, and next-generation sequencing. This review emphatically introduces the setup of the ADE system and the critical technologies of each part, including acoustic droplet generation, optimized design of the source fluid wells, droplet coalescence, and power control. The advantages and disadvantages of these technologies are discussed, and the future development of acoustic droplet ejection technology is also predicted.