Measuring tiny forces

Backholm, M. and Bäumchen, O. Nat Protoc 14, 594–615 (2019)

Mechanical forces, if tiny ones, are hard at work in the body of small organisms like Caenorhabditis elegans worms or microalgae like the flagellated Chlamydomonas. Pico-to-millinewton-scale forces govern the dynamics between molecules and cells and are produced as the small creatures move about, but taking those measurements has been technically challenging. A protocol to do so, originally demonstrated with Chlamydomonas in Nature Physics has now been described in step-by-step detail in Nature Protocols. The researchers use swimming C. elegans as an example application, but the sensor can be used record forces in soft samples that are micro- to millimeters in size. It involves creating a force sensor from a flexible micropipette and calibrating it with water droplets. Deflections in the micropipette reflect the force being exerted.