Yet, for biological cells and microbes, these forces are enough to allow cells to stick to a surface or microbes to propel themselves towards nutrients.
Scientists from Finland and Germany now present a highly adaptable technique, called 'micropipette force sensors', to precisely measure the forces exerted by a wide range of micron-sized organisms.
The ability to do so involves physical principles and mechanical forces: cells may attach themselves to surfaces and other cells to eventually form a biofilm, a structure which protects the community of cells from external attack.
Many microorganisms can actively move themselves, by crawling on a surface or swimming in liquid, for example, towards a source of nutrients.
"The working principle of the micropipette force sensor technique is beautifully simple: by optically observing the deflection of a calibrated micropipette, the forces acting on the pipette can be directly measured", says Matilda Backholm, researcher at the Department of Applied Physics of Aalto University in Finland.
A micropipette is a hollow glass needle featuring a thickness of about the diameter of a human hair or even smaller.