IMAGING THE TRACTION STRESSES EXERTED BY LOCOMOTING CELLS WITH THE ELASTIC SUBSTRATUM METHOD

The cytoskeletal activity of motile or adherent cells is frequently se en to induce detectable displacements of sufficiently compliant substr ata. The physics of this phenomenon is discussed in terms of the class ical theory of small-strain, plane-stress elasticity. The main result of such analysis is a transform expressing the displacement field of t he elastic substrate as an integral over the traction field. The exist ence of this transform is used to derive a Bayesian method for convert ing noisy measurements of substratum displacement into ''images'' of t he actual traction forces exerted by adherent or locomoting cells. Fin ally, the Monte Carlo validation of the statistical method is discusse d, some new rheological studies of films are presented, and a practica l application is given.