Abstract: An adjustable seal includes a first ring extending about an axis and including a plurality of first teeth. The adjustable seal also includes a second ring extending about the axis and including a plurality of second teeth. The first ring and the second ring cooperatively defining a passage extending along the axis. The adjustable seal has a locked configuration in which the second teeth engage the first teeth and prevent movement of the first ring relative to the second ring, and an unlocked configuration in which the first ring is able to rotate relative to the second ring. The adjustable seal also includes a flexible member attached to the first ring and the second ring. Rotation of the first ring relative to the second ring in the unlocked configuration of the adjustable seal causes the flexible member to extend across at least a portion of the passage defined by the first ring and the second ring.

Abstract: The disclosure provides for a variable stiffness catheter. The catheter may include an inner layer forming an inner lumen, a middle layer surrounding the inner layer, and an outer layer surrounding the middle layer. The middle layer may include an annular lumen and a plurality of strings within the annular lumen, and the plurality of strings may be connected to the inner layer. Applying a vacuum and evacuating the annular lumen of the middle layer alters a frictional force between the inner layer and the outer layer and thereby changes the catheter's flexural rigidity.