FIGURE 2.

(A,B) 2-D TFM: cells are seeded on top of a hydrogel substrate containing fluorescent beads (A) or elastic micropillars (B). Traction Forces can be measured through the imaging of the beads’ displacements or deflections of micropillars. (C) 3-D TFM (top) and 3-D MSM (bottom): 3-D TFM takes vertical direction displacement into account by comparing 3-D interrogate boxes between the deformed and undeformed state of substrates. 3-D MSM is derived from 3-D TFM and takes bending effects on cellular tensions into account. (D) AFM: A cantilever beam with a probing tip at one end applies a force onto the cell. (E) PFM: cells are seeded onto a formvar substrate, which is then stretched over a mesh grid. This formvar membrane is place upside, allowing for accurate topological information about the podosomes to be recorded through AFM. With the use of mathematical modeling, forces exerted by the podosomes can be calculated. (F) ERISM: thin transparent gold films are placed on top of and below an ultra-soft siloxane-based elastomer. The top gold film is protein coated to allow for cell adhesion. Local deformation caused by the cell to the elastomer form resonance fringes that are captured using established imaging modalities. (G) MT-FILM: surface functionalization of SLB with FRET-based DNA tension probe. When the integrin force applied is greater than F_1/2, the rated force the probe can handle, the linker arms come together and open, causing the florescence of the probe increases. (H) microsphere-based TFM: Microspheres with fluorescent beads embedded are placed within multilayer of cells. After a few days, the cells exert compressive forces that deform the microspheres.