An ablation device for treatment of tissue in body lumens with varying sizes, the device comprising: a catheter (115)； an expansion member (120) coupled with a distal portion of the catheter； an ablation structure (160) comprising a plurality of longitudinal electrode regions (502,504,506,702-718,802-810,902-912,1006-1016) wherein each of the electrode regions is configured to be selectively enabled or disabled； an ablation structure support (180) coupled with the ablation structure, wherein the ablation structure (160) and the ablation structure support (180) are configured to at least partially unfurl or furl around the expansion member (120) as the expansion member expands or contracts, the ablation device being arranged so that as the expansion member expands and the ablation structure unfurls, longitudinal electrode regions are exposed from beneath an overlapping portion of the ablation structure； and a power source (105) configured to selectively enable the plurality of longitudinal electrode regions, characterized in that the power source is configured to sequentially enable the longitudinal electrode regions starting with the longitudinal electrode region (502,702,802, 902,1006) adjacent a free edge (181) of the ablation structure (160), the power source being further configured to detect a first electrode region that is fully shielded by the overlapping portion of the ablation structure and to stop the sequential enabling of the longitudinal electrode regions when the first fully shielded longitudinal electrode region is detected.
