Because device dimensions and the gaps between samples are getting smaller, very small and fast drives are needed for the pipetting process.
At the same time they must produce sufficient force to move the pipettes in the vertical direction and to dose the media.

This is not a problem for piezomotors. They operate with a tiny footprint as a direct linear drive and can generate high forces. A ceramic oscillating with ultrasonic frequencies generates a controllable forward motion with uniform speed and micrometer accuracy.