a, A fibroblast cell on a bed of microneedles. The actin fibres are stained green. The arrows show the force exerted on the microneedles. b, Time evolution of the force exerted by a square cell on an array of four posts plotted for three values of the normalized support stiffness, k. The distribution of the average stress fibre activation over all orientations at steady state is also shown. The filled circles indicate the original positions of the cell corners. (Figure reprinted in part with permission from ref. 57.)
© 2006 NAS, USA]