The invention relates to a cartridge for an aerosol-generating system. The cartridge comprises a liquid storage portion (10, 10.1), which comprises a housing (12, 12.1) holding a liquid aerosol-forming substrate. The housing (12, 12.1) has a first and a second opening (14, 14.1). The cartridge further comprises a first and a second permeable planar heater assembly (16, 6.1), wherein the first planar heater assembly (16) is fixed to the housing (12, 12.1) and extends across the first opening (14) of the housing (12, 12.1), and the second planar heater assembly (16.1) is fixed to the housing (12, 12.1) and extends across the second opening (14.1) of the housing (12, 12.1). The first and second permeable planar heater assemblies (16, 6.1) are arranged opposite each other such that they face each other and form an airflow channel (20) in between each other.
