A method for separating cells developed by researchers at North Carolina State University (Raleigh) and the University of North Carolina at Chapel Hill relies on sound waves. The technique, according to Xiaoning Jiang, an associate professor of mechanical and aerospace engineering and adjunct professor of biomedical engineering at NC State, could accelerate and simplify the process of sorting out live cells for research purposes.
Cell types respond to various chemicals or environmental factors. They are often grown in a liquid medium atop micropallets—essentially small plastic platforms that sit on the substrate at the bottom of the container. To analyze the cells, researchers select the ones they want and detach the relevant micropallets.
Current methods for removing these micropallets rely on lasers or physical manipulation to separate the pallets from the substrate. However, while physical manipulation is slow, the laser energy used to release micropallets 500 µm or larger in diameter can inadvertently kill many cells. Moreover, neither technique can efficiently detach a significant number of large micropallets quickly.
The new ultrasound technique releases the micropallets using focused, relatively high-frequency sound waves that are translated into a wave of pressure within the substrate itself. When that wave strikes a targeted micropallet, the pallet is lifted off the substrate. Using this method, micropallets can be selectively released in less than a millisecond. While this technique is slower than laser-based methods, it has a viability rate greater than 90%.
The following video highlights this process.