Acoustopipetting: Tunable Nanoliter Sample Dispensing Using Surface Acoustic Waves.

We seek to demonstrate a robust, low-cost, and user-friendly acoustomicrofluidic platform that facilitates rapid, reproducible, and precise nanoliter sample dispensing. The solid-state chipscale platform exploits the unprecedented acceleration arising from high-frequency nanoelectromechanical vibrations, on the order of 10 million g, to jet the sample and hence generate a liquid bridge that spans across the substrate, on which the vibrations are generated and from which the sample originates, to a top target plate before rapidly pinching off to deposit the sample on the target with precise and reproducible volumes that can be tuned down to 0.22 μL with a standard error of 6.5% and coefficient of variation of 11.3%. The entire process occurs within approximately 10 ms. In addition to explicating the fundamental physical mechanism that underpins the technology, we demonstrate its use for serial dilution and concentration and, in particular, a cell-based drug toxicology assay. Moreover, we also show that multiple drop dispensing in an array, without requiring repositioning of the chip between dispensing steps, can be achieved through a simple but yet effective sequential directional jetting strategy, therefore allowing significant reduction in the total dispensing time in the case of massive-scale microarray operation. Given its low cost and compact size, the platform can easily be automated and parallelized, thus offering the prospect for introducing large-scale efficiencies in the laboratory workflow.