Here's a nice new microfluidic technique for studying cell mechanics by looking at the deformation of permeable elastic capsules as cells grow as spheroids within the confines of the capsules. This is thus a measure of the force exerted by the growing multicellular spheroids. The organization and behavior of the cells can be imaged and analyzed as well. The authors used their technique to look at tumor cell growth. They found that the compressive restoring force of the capsule results in formation of a solid-like core of denatured extracellular proteins and a peripheral rim of highly motile cells. The hyper-motile cells appear to have an invasive phenotype.