“…One is dispersing high–ε r inorganic fillers into an insulating polymer [ 18 ], such as Pb(Zr 1−x Ti x )O 3 (PZT), BaSrTiO 3 , and others. Generally speaking, a decent increase in ε r can be observed in the composites only when the filler concentration is nearly close to 65 wt% [ 19 , 20 , 21 , 22 ], which will inevitably destroy the processing [ 23 , 24 , 25 , 26 , 27 , 28 ], optical and mechanical performances of the composites [ 29 ]. Another approach to solve this question is based on percolating composites by using the conductive particles, such as copper (Cu) [ 23 ], zinc (Zn) [ 24 ], iron (Fe) [ 25 ], silver (Ag) [ 26 ] and carbon materials such as nanotubes (CNTs) [ 27 ].…”