Humidifier and layered heating element

1. A humidifier for humidifying a pressurized flow of breathable gas for respiratory therapy for a patient, comprising:

a gas inlet configured to receive gas from a flow generator;

a tub adapted to hold a liquid, the tub including sidewalls and a bottom wall joined to the sidewalls;

a gas outlet adapted to be connectable to a tube to provide humidified gas to a patient interface;

a heating apparatus including:

a hot plate to contact the liquid;

a heating element having a first side and a second side, the heating element including a copper or alloy or Positive Temperature Coefficient (PTC) layer with heating tracks to in use provide heat to heat the liquid in the tub;

a first thermally conductive laminate layer provided on the first side of the heating element and in thermal contact with the hot plate; and

a protective layer provided on the second side of the heating element,

wherein the bottom wall is overmolded onto the heating apparatus such that the heating apparatus is embedded in the bottom wall.

2. The humidifier according to claim 1 , wherein a substrate is provided to an end portion of the heating element to form a connector section.

3. The humidifier according to claim 2 , wherein the end portion of the heating element forms an electrical contact to receive electrical power.

4. The humidifier according to claim 1 , wherein the heating element is a metal printed circuit board (PCB).

5. The humidifier according to claim 1 , wherein portions of the copper or alloy or PTC layer of the heating apparatus are etched to form the heating tracks of the heating element.

6. The humidifier according to claim 1 , wherein the heating element includes conductive metal foils.

7. The humidifier according to claim 1 , wherein the heating element is arranged in a serpentine pattern.

8. The humidifier according to claim 1 , wherein at least a portion of the heating tracks has a width in a range of about 0.3 mm to 2 mm.

9. The humidifier according to claim 1 , wherein the heating tracks are associated with contact pads for electrical leads and at least one electrical component.

10. The humidifier according to claim 1 , wherein in use the temperature of the heating apparatus is determined by determining a resistance of the heating tracks.

11. The humidifier according to claim 1 , wherein the sidewalls are overmolded onto the heating apparatus.

12. The humidifier according to claim 11 , wherein the protective layer includes a solder mask.

13. The humidifier according to claim 1 , wherein the first thermally conductive laminate layer is a first dielectric laminate layer.

14. The humidifier according to claim 13 , wherein the bottom wall is overmolded over peripheral edges of the first dielectric laminate layer, the heating element and the protective layer.

15. The humidifier according to claim 13 , wherein the first dielectric laminate layer comprises at least one of a ceramic, a polymer, a polymeric mixture, polytetrafluoroethylene, polyimides, boron nitride, alumina, beryllium oxide, aluminum nitride, boron nitride, epoxy composite, and reinforced fiberglass.

16. The humidifier according to claim 15 , wherein the first dielectric laminate layer is constructed from a flexible polyimide film.

17. The humidifier according to claim 13 , wherein the first dielectric laminate layer has a thickness in a range of 20 um to 160 um.

18. The humidifier according to claim 13 , wherein the first dielectric laminate layer has a dielectric breakdown voltage above 2 kV.

19. The humidifier according to claim 1 , wherein the heating apparatus is provided to a humidifier chamber adapted to receive the tub.

20. The humidifier according to claim 19 , wherein the heating apparatus is integral with the tub.