A guidewire including a thin elongated structure and an outer shell around at least a portion of the thin elongated structure. The outer shell includes a first portion and a second portion. The first portion and the second portion of the outer shell are each coupled to the thin elongated structure. The first portion is spaced from the second portion by a gap. The guidewire is configured to move between a flexible state and a rigid state. The gap has a first distance when the guidewire is in the flexible state and the gap has a second distance greater than the first distance when the guidewire is in the rigid state.
