Triboelectric effect

What is meant by the triboelectric effect?

The term was derived from the Latin word tribere = to rub. The effect describes the electrical charging of two materials through friction. Every material is characterized by a dielectric constant which defines the surface charge density. When two materials rub each other, they become charged depending on the dielectric constants.

On the material side, surface roughness, surface geometries and oxidation can favour this effect. Environmental influences such as air pressure and pollution also cause build-up of charge. 

How does the tribolectric effect influence the measurement signal of piezoelectric measurement technology?

Piezoelectric measurement technology is suitable to capture minimal charge signals within the range of a few Pico Coulombs. Therefore any additional type of charge will cause a change in the measurement signal. The triboelectric effect affects cables and plug connections and thus is a source of interference for the measurement signal that cannot be neglected.