Cell migration is essential for a variety of biological and pathological processes such as wound healing, inflammation and tumor metastasis. However, the mechanical environment within a group of cells during collective migration has not been well characterized. In this study, a polydimethylsiloxane (PDMS) multichannel device was fabricated using standard photolithography and soft lithography techniques and was used to monitor cellular traction forces during migration. A migration rate of 5.7 μm/h was measured in microchannels and leading cells in the moving front of the migration generated traction forces with a maximum magnitude of 14 nN at their front side. Traction forces generated by cells behind the leading cells directed forces backward at both the front and rear sides. However, traction forces generated by cells behind the second row had forces in random directions and with smaller magnitudes compared to those on the front and the second row. It is assumed that cells on the front line generated large traction forces and migrated actively as single cells, pulling adjacent cells forward, whereas the cell movement after the third row was restricted by mechanical linkages between their neighboring cells.
