Sorting cells with sound

    A new sound-based method of sorting cells will provide a gentler alternative to current methods--and could lead to an earlier diagnosis of some cancers.
   Sorting cells with sound waves involves using microfluidic devices equipped with a pair of acoustic transducers. The transducers create a wave that in turn creates a pressure node, pushing the cells to the side of the channel; how far each cell moves is in part determined by its size--which allows them to be sorted.
   The new sorting device will be similar, but it will improve on the previous version by placing the transducers at an angle, creating several pressure node areas along the channel. As the cells travel through the channel, they will be nudged a bit more off center at each pressure node, which will allow them to be sorted more precisely by size. This technology will be particularly useful at detecting the rare circulating tumor cells (CTCs) that are used to identify and monitor cancer.