Devices and methods for treatment of luminal tissue

An electrode deployment apparatus for treatment of tissue in a body lumen, the apparatus comprising:

• a plurality of electrodes arranged on a surface of a dimensionally stable support at a pre-selected electrode density;
• an expansion member comprising an inflatable balloon coupled to the support to deploy and selectively expose a portion of the electrode surface while shielding a remaining portion and maintaining the electrode density;
• and
• a shaft and a sheath, wherein the support is attached at one end to a distal end of the shaft and spirally furled about the shaft, wherein the balloon is slidably received on the shaft proximal to the support, wherein the balloon and support are retained in the sheath so that they may be advanced past the sheath once the apparatus is positioned at a treatment area, and wherein the balloon is further advanced to the distal end of the shaft to expand the support.