Cantilever Array Weighs Single Cells

A new array of microfabricated silicon cantilevers gives researchers a way to track the growth of individual adherent cells (Lab Chip, DOI: 10.1039/b803601b). Common methods for characterizing single cells, such as flow cytometry, require that cells be suspended in solution. But many so-called adherent cells, such as fibroblast and epithelial cells, must be attached to a surface to grow. Rashid Bashir of the University of Illinois, Urbana-Champaign, and coworkers describe arrays of silicon cantilevers that can determine the mass of individual adherent cells without detaching them from the surface. The researchers calculate cell mass by measuring cell-growth-induced changes in each cantilever's resonance frequency, which is inversely proportional to the square root of its mass. Cells on the cantilever surface change the device's effective mass and thus its resonance frequency. The researchers cultured cancer cells on the cantilevers and calculated the cells' mass from resonance frequency shifts of the cantilevers. Because the cells don't need to be detached from the surface, the technology can be used for time-course studies of individual cells.