Out of Berkeley comes news of a new way to sort cells using ‘optoelectronic tweezers’:
The UC Berkeley engineers found a way to get the best of both worlds by transforming optical energy to electrical energy through the use of a photoconductive surface. The idea is similar to that used in the ubiquitous office copier machine. In xerography, a document is scanned and transferred onto a photosensitive drum, which attracts dyes of carbon particles that are rolled onto a piece of paper to reproduce the image.
In this case, the researchers use a photosensitive surface made of amorphous silicon, a common material used in solar cells and flat-panel displays. Microscopic polystyrene particles suspended in a liquid were sandwiched between a piece of glass and the photoconductive material. Wherever light would hit the photosensitive material, it would behave like a conducting electrode, while areas not exposed to light would behave like a non-conducting insulator. Once a light source is removed, the photosensitive material returns to normal.
They compare this new technique favorably to recent advances in cell manipulation with optic tweezers or electric fields. One obvious comparison that was missed is the fluorescent-activated cell sorter (FACS). When it comes to sorting live vs. dead cells, or sorting based on size, like Wu’s lab does, FACS is a proven technology. What makes this Berkeley finding really special, though, is that the cells can be kept in their culture environment while sorted. FACS was far more disruptive — a fact some of us lamented during our research years…
More from Dr. Ming Wu’s article in this week’s Nature…