Induction heater for a cooking surface

An induction heater for a cook top comprising:

• a first electrically insulating sheet;
• a second electrically insulating sheet;
• one or more inductors arranged on a same plane between the first electrically insulating sheet and the second electrically insulating sheet, each inductor of said one or more inductors comprising a single electrically conductive track defining a flat spiral coil;
• at least one magnetic flux concentrator arranged on a plane under the second electrically insulating sheet;
• a metallic heat sink plate arranged under the at least one magnetic flux concentrator, adapted to dissipate the heat produced by the one or more inductors;
• wherein each turn of a plurality of turns of each inductor is shaped so as to have four rectilinear stretches parallel in pairs, and four curved stretches, wherein two mutually successive rectilinear stretches are joined by a respective curved stretch;
• wherein the radius of curvature of the curved stretches gradually increases from the innermost turn to the outermost turn.