Abstract: A flexible sensor includes a main substrate having flexibility, a transistor over the main substrate, a support substrate over the transistor, wherein the support substrate has flexibility and at least an outer surface of the support substrate comprises a material having electric insulation, and a variable resistance part over a first surface which is an upper surface of the support substrate, in which a resistance value of the variable resistance part changes according to strain of the variable resistance part.

Abstract: Disclosed is a highly dense aggregate of brittle material particles having an interface at which the particles are bonded to each other and pores between the brittle material particles structuring the highly dense aggregate, where a porosity which is a volume ratio of the pores with respect to the whole of the highly dense aggregate is equal to or less than 20%, and a volume ratio of the pores communicating with an apparent outer surface of the highly dense aggregate with respect to a volume of all of the pores of the highly dense aggregate is equal to or higher than 65%.