A little less force: Making atomic force microscopy work for cells
Atomic force microscopy, a tactile-based probe technique, provides a three-dimensional nanoscale image of a material by gliding a needle-like arm across the material's surface. The core of AFM imaging workhorse is a cantilever with a sharp tip that deflects as it encounters undulations across a surface. Due to a minimum force required for imaging, conventional AFM cantilevers can deform or even tear apart living cells and other biological materials. While scientists have made strides in reducing this minimum force by making smaller cantilevers, the force is still too great to image cells with high resolution. Indeed, for imaging objects smaller than the diffraction limit of light—that is, nanometer dimensions—this approach hits a roadblock as the instrument can no longer sense minute forces.