Figure 2.

Methods for applying forces to cilia. (a) Direct application of mechanical forces onto the cilia themselves—for example, using glass needles or optical tweezers. This method has the advantage that the exact spot of force application can be controlled. (b) Fluid flow. This method has the advantage that it may mimic the types of forces present in many physiological systems, such as the endothelium or kidney tubules. (c) Stretching the cell, either by adhering the cell to a patterned substrate that forces the cell to increase its spread surface area or by physically stretching the substrate after the cell has adhered.