preparing a base substrate including an embossed pattern;

forming a first conductive layer on the base substrate, wherein the first conductive layer has a curved surface corresponding to the embossed pattern;

fixing the base substrate including the first conductive layer to an omnidirectional stretching device and then planarizing the curved surface of the first conductive layer by applying a tensile force to the base substrate in all directions;

forming a pressure sensitive material layer on the first conductive layer having the planarized surface, wherein the pressure sensitive material includes a dielectric and nanoparticles dispersed in the dielectric; and

forming a second conductive layer on the pressure sensitive material layer,

where the dielectric and the nanoparticle include materials having pyroelectricities of polarities opposite to each other.