Heater assembly for an aerosol-generating system
A heater assembly ( 300 ) for an aerosol-generating system, the heater assembly comprising: a fluid permeable heater ( 322 ) for heating a liquid aerosol-forming substrate to form an aerosol; a porous member ( 324 ) for conveying liquid aerosol-forming substrate to the fluid permeable heater, wherein the fluid permeable heater is deposited on to a porous outer surface ( 324 a ) of the porous member, the fluid permeable heater comprising: a first layer ( 326 ) of deposited electrically conductive material; a second layer ( 328 ) of deposited electrically conductive material, wherein the electrical conductivity of the second layer is greater than the electrical conductivity of the first layer such that the second layer modifies the electrical resistance of the fluid permeable heater to a required resistance.
1. A heater assembly for an aerosol-generating system, the heater assembly comprising:
a fluid permeable heater for heating a liquid aerosol-forming substrate to form an aerosol;
a porous member for conveying liquid aerosol-forming substrate to the fluid permeable heater,
wherein the fluid permeable heater is deposited on to a porous outer surface of the porous member, the fluid permeable heater comprising:
a first layer of deposited electrically conductive material;
a second layer of deposited electrically conductive material, wherein the electrical conductivity of the second layer is greater than the electrical conductivity of the first layer such that the second layer modifies the electrical resistance of the fluid permeable heater to a required resistance.
2. The heater assembly according to claim 1 , wherein the first layer is deposited directly on the porous outer surface of the porous member.
3. The heater assembly according to claim 1 , wherein the fluid permeable heater further comprises a third layer arranged between the porous outer surface of the porous member and the first layer.
4. The heater assembly according to claim 3 , wherein the third layer acts as an adhesion layer to improve the adhesion between the first layer and the porous outer surface of the porous member.
5. The heater assembly according to claim 3 , wherein the third layer comprises a material selected from one or more of Tantalum, Titanium and Chromium.
6. The heater assembly according to claim 1 , wherein the second layer is deposited on the first layer.
7. The heater assembly according to claim 1 , wherein the second layer comprises a material having a resistivity of less than 5×10 −8 Ωm.
8. The heater assembly according to claim 1 , wherein the thickness of the second layer is between 10 and 20 nm.
9. The heater assembly according to claim 3 , wherein the thickness of the third layer is between 10 and 20 nm.
10. The heater assembly according to claim 1 , wherein the second layer modifies the electrical resistance of the fluid permeable heater to between 0.3 and 4 Ohms, more particularly between 0.5 and 1.5 Ohms and yet more particularly 1 Ohm.
11. A cartridge for use in an aerosol-generating system, the cartridge comprising a liquid storage portion for holding a liquid aerosol-forming substrate; and the heater assembly according to claim 1 .
12. The cartridge according to claim 11 , wherein the fluid permeable heater is deposited on to a porous first end of the porous member and wherein a second end of the porous member extends into the liquid storage portion for contact with the liquid aerosol-forming substrate therein.
13. An aerosol-generating system comprising:
an aerosol-generating device; and
the cartridge according to claim 11 ,
wherein the cartridge is removably coupled to the aerosol-generating device and the aerosol-generating device includes a power supply for the heater assembly.
14. A method of manufacturing a heater assembly for an aerosol-generating system, the method comprising:
providing a porous member;
depositing a fluid permeable heater onto a porous outer surface of the porous member, the fluid permeable heater comprising:
a first layer of deposited electrically conductive material;
a second layer of deposited electrically conductive material;
wherein the electrical conductivity of the second layer is greater than the electrical conductivity of the first layer such that the second layer modifies the electrical resistance of the fluid permeable heater to a required resistance.
15. The method according to claim 14 , wherein the first and second layers are deposited by physical vapour deposition (PVD) or plasma-enhanced chemical vapour deposition (PECVD).