This disclosure provides design, material, manufacturing method, and use alternatives for medical devices. An example medical device includes a scaffold including a central member and a plurality of extension members extending away from the central member. The central member includes a plurality of discrete attachment locations corresponding to each of the plurality of extension members and each of the plurality of extension members is pivotably coupled to the central member at a corresponding discrete attachment location. The medical device also includes a covering substantially surrounding the scaffold and an electrode located at a distal end of each of the plurality of extension members. Each electrode extends through at least a portion of the covering.