To put these dimensions into perspective, let's compare the size of this hair cell to something more familiar. This cover of Scientific American shows a scanning electron micrograph of an ant. The ant is holding a tiny microfabricated gear, and the point of the cover is that we can now fabricate mechanical parts that are small compared to ants. To illustrate the size of a hair cell, I have electronically pasted the image of the hair cell onto the microfabricated gear. You will have to zoom in to see it.
Hair cells are small.
But hair cells are themselves complex micromechanical systems whose function relies on an array of even smaller mechanical parts. Displacements of hair bundles generate electrical responses in hair cells via mechanically sensitive ion channels in the cell membrane. Ion channels are proteins that are integral parts of the membranes of all cells. Most of the cell's membrane is lipid and acts as a chemical and electrical barrier between the inside and outside of the cell. Ion channels have pores that act as conduits for ionic currents to pass through the membrane.