An aerosol-generating device is provided, including a reservoir configured to hold a liquid; a release medium; and a heater, wherein the reservoir and the release medium are configured to transport liquid from the reservoir to the release medium, wherein the release medium and the heater are disposed in physical contact with each other, wherein the aerosol-generating device further includes a means for reversibly releasing the physical contact between the release medium and the heater to form a gap between the heater and the release medium, and wherein the aerosol-generating device is configured to activate the heater when the gap is formed between the heater and the release medium. A method for forming an aerosol by the aerosol-generating device is also provided.