An aerosol-generating system comprising a fluid-permeable electric heater assembly (30), the heater assembly comprising: an electrically insulating substrate (34), an aperture being formed in the electrically insulating substrate; and a heater element having a first face fixed to the electrically insulating substrate, the heater element spanning the aperture and comprising a plurality of electrically conductive filaments (36) connected to first and second electrically conductive contact portions (32), the first and second electrically conductive contact portions positioned on opposite sides of the aperture to one another, wherein the first and second electrically conductive contact portions are configured to allow contact with an external power supply.