Highly insulating cables

Why are highly insulating cables an important component of piezoelectric measurement technology?

By using the piezoelectric effect and the respective piezoelectric measurement technology, measured quantities in the range of a few pico coulombs (pC = 10-12 coulombs) can be acquired. In order to transport electrical charge in this very small quantity loss-free and without additional signal noise, high-quality cables and plug connections within the entire measurement chain are a fundamental component.

The structure of a high-insulating cable consists in multiple layers of different, insulating materials.
Structure of highly insulating cables: Several layers consisting of different insulating materials reduce additional signal noise as well as drift effects.

Reliable signal transmission requires an insulation resistance of the cable solution used of more than 10^13 Ω. The requirements for a high insulation resistance can be achieved with a special structure of the cable layers:

This structure consists of an outer insulator, an electrical shield made of PTFE, a special sheath made of conductive graphite and another electrical insulator, which surround the inner cable. The special graphite coating reduces the triboelectric effect within the cable and the PTFE layer reduces drift in the signal.

The described construction is called coaxial shielding and has the advantage of isolating the measurement signal from interference signals and ensuring the transmission of the measurement signal with low loss.