A temperature sensor comprises at least one temperature sensing device and a sensing circuit. The temperature sensing device comprises a first electrode layer, a second electrode layer and a current-sensitive layer, wherein at least one of the first and second electrode layers comprises two electrically separated electrode plates, and the current-sensitive layer is laminated between the first and second electrode layers. The current-sensitive layer is made of PTC or NTC material, and the sidewalls are not plated with conductive films. The sensing circuit is electrically coupled to the temperature sensing device to read temperatures.