Surface acoustic wave actuated cell sorting (SAWACS)
Oftentimes, in both research and in clinical settings, it is important to sort cells- that is, to separate some group of cells into two or more groups. There are a few methods for accomplishing this out there already. In the big picture, there are two types of sorting techniques: droplet sorting and continuous flow sorting. In droplet sorting, the cells are somehow encapsulated into a droplet, and the droplets are sorted. The sorting can be accomplished by using liquid for the droplets that has very different polarizability, charge, miscibility, etc. than the surrounding liquid. However, droplet sorting has its disadvantages, as the encapsulation requires an extra step in the sorting process, and sometimes one may not want the cells to be encapsulated in a droplet for whatever it is one wants to do with the cells after sorting. Continuous cell sorting, on the contrary, does not require the cells to be encapsulated in the droplet but are separated continuously. One common way in which this is done is by selectively attaching magnetic beads to the cells, and then using a magnetic force to sort the cells. However, most continuous cell sorting schemes are slow as compared with the droplet sorting schemes. This paper presents a new method for continuous cell sorting that uses surface acoustic waves to actuate the cells.