A very small piezoelectric sensor capable of being mass produced includes a core, a piezoelectric layer on a surface of the core; and a conductive layer on a surface of the piezoelectric layer away from the core. The core is flexible and threadlike, the core is a first electrode of the piezoelectric sensor, and the conductive layer is a second electrode of the piezoelectric sensor. An array of such sensors allows the “skin” of a robot for example to simulate the sensitivity of hair-covered human skin. A method for making the piezoelectric sensor and an electronic device using the piezoelectric sensor are also disclosed.