The detail power generation mechanism of the NCG device
is described in Figure S9. In addition, we calculate the piezopotential
distributions inside the NCG by using a simple rectangular
model composed of six BaTiO 3 NPs in a PDMS matrix
(see Method S3) as shown in Figure 3 a and b. The material
parameters of the BaTiO 3 and PDMS, which are taken from
the COMSOL simulation software, are used for the fi nite element
analysis. [ 27 ]