Foreign object detection using combined inductive and thermal sensing

An apparatus for detecting a presence of a foreign object in an inductive wireless power transfer system, the apparatus comprising:

• a sensing system configured to sense the foreign object based on one or more of an inductive effect and a thermal effect, the sensing system including:
• a sense element having an electrical characteristic, the sense element being configured to sense the foreign object based on the inductive effect related to a first alternating magnetic field;
• and
• a mediating heat-sensitive material coupled to, but electrically separate from, the sense element, wherein the mediating heat-sensitive material has a property that varies as a function of temperature when heated by the foreign object exposed to a second alternating magnetic field generated by the inductive wireless power transfer system, wherein the mediating heat-sensitive material changes the electrical characteristic of the sense element as a function of the property;
• and
• a controller coupled to the sensing system, the controller configured to:
• measure the electrical characteristic of the sense element;
• and
• determine the presence of the foreign object based on the change in the measured electrical characteristic caused by at least one of the inductive effect and the thermal effect through the mediating heat-sensitive material.