A heater device includes a heater surface facing one side in a predetermined direction. The heater device includes a transmission electrode and a reception electrode arranged on the other side in the predetermined direction with respect to the heater surface, and an insulation coating layer that covers the transmission electrode and the reception electrode on the one side in the predetermined direction. The transmission electrode and the reception electrode are electrically connected to a contact detection unit, to detect contact or proximity of an object to the heater surface by a change in a capacitance therebetween. The insulation coating layer has a first component part made of an insulating member, and a second component part having a smaller relative permittivity than that of the first component part. The second component part is located between at least one of the transmission electrode or the reception electrode and the heater surface.

A fluid permeable heater assembly for an aerosol-generating system includes a cap and a substantially flat electrically conductive and fluid permeable heating element. The cap includes a hollow body with a first cap opening and a second cap opening. The first cap opening is opposite to the second cap opening. The heating element is configured to vaporise aerosol-forming substrate. The heating element is mounted on the cap, such that the heating element extends across the first cap opening. A cartridge for an aerosol-generating system includes the heater assembly, a liquid storage portion, a mouth piece, and a retainer.

An electrically operated aerosol-generating system may be configured to detect adverse conditions (e.g., a dry heater). The system may comprise an electric heater comprising at least one heating element for heating an aerosol-forming substrate, a power supply, and electric circuitry connected to the electric heater and to the power supply and comprising a memory. The electric circuitry may be configured to measure an initial electrical resistance (R.sub.1) of the electric heater; measure a subsequent electrical resistance of the electric heater after the measurement of the initial electrical resistance; determine the difference (R) between the initial electrical resistance and the subsequent electrical resistance; determine that an adverse condition is present if the difference is greater than a maximum threshold value (R.sub.max) or less than a minimum threshold value (R.sub.min) stored in the memory; and control a power to the electric heater and/or provide an indication if the adverse condition is present.

A fluid permeable heater assembly for an aerosol-generating system includes a cap and a substantially flat electrically conductive and fluid permeable heating element. The cap includes a hollow body with a first cap opening and a second cap opening. The first cap opening is opposite to the second cap opening. The heating element is configured to vaporise aerosol-forming substrate. The heating element is mounted on the cap, such that the heating element extends across the first cap opening. A cartridge for an aerosol-generating system includes the heater assembly, a liquid storage portion, a mouth piece, and a retainer.