  Triboelectric nanogenerators (TENGs) are an emerging mechanical energy
harvesting technology that was recently demonstrated. Due to their flexibility,
they can be fabricated in various configurations and consequently have a large
number of applications. Here, we present a study on the influence of the
thickness of the triboelectric layer and of the contact surface area between
two triboelectrical materials on the electric signals generated by a TENG.
Using the PDMS-Nylon tribo-pair, and varying the thickness of the PDMS layer,
we demonstrate that the generated voltage decreases with increasing thickness.
However, the maximum generated current presents an inverse behaviour,
increasing with increasing PDMS thickness. The maximum output power initially
increases with increasing PDMS thickness up to 32 um, followed by a sharp
decrease. Using the same tribo-pair (but now with a constant PDMS thickness),
we verified that increasing the contact surface area between the two
tribo-materials increases the electrical signals generated from the
triboelectric effect.
