A medical device comprises a substrate (10) defining a major surface (9) defining a plane, including a plurality of first struts (14) along a first direction interconnected with a plurality of second struts (12) extending along a second direction not parallel with the first direction, wherein widths (11) of the second struts as measured along the major surface are larger than thicknesses of the second struts as measured perpendicular to the major surface such that when the substrate is stretched in the first direction, intermediate sections (15) of the second struts (12) rotate relative to the first struts (14) and the intermediate sections of the second struts bend out of the plane of the major surface. The medical device is operable to extend and/or retract elements suitable for a particular purpose. The elements are extended and/or retracted in response to a stress applied by way of stretching and/or retracting the device, among other methods. The elements may remain extended and/or retracted or may recoil back to an initial position upon the removal of the force. In various embodiments, the elements are used to treat or deliver treatment to a target site within a body.