Method for manufacturing a steerable instrument and such steerable instrument
A steerable instrument for endoscopic and/or invasive type applications includes an elongated tubular body having a proximal end part, a distal end part and an intermediate part between proximal and distal end parts, the proximal end part having at least one actuation proximal zone. The distal end part has at least one flexible distal zone, and the elongated tubular body is configured such that a movement of an actuation proximal zone is transferred to a corresponding flexible distal zone for a corresponding movement thereof. The elongated tubular body includes an inner, outer, and intermediate cylindrical elements having longitudinal elements between the inner and outer cylindrical elements. Inner, outer and intermediate cylindrical elements are coupled so movement of an actuation proximal zone is transferred by the longitudinal elements of one of the intermediate cylindrical elements to a corresponding flexible distal zone.
1 . A method for manufacturing a steerable instrument for endoscopic and/or invasive type applications, such as in surgery, the instrument including:
an elongated tubular body having a proximal end part, a distal end part and an intermediate part between the proximal end part and the distal end part, the proximal end part having at least one actuation proximal zone, the distal end part having at least one flexible distal zone,
the elongated tubular body including an inner cylindrical element, an outer cylindrical element and at least one intermediate cylindrical element, each of which having a first longitudinal element and a second longitudinal element and being provided between the inner and outer cylindrical elements,
the method including:
providing the inner and outer cylindrical elements; and
incorporating the at least one intermediate cylindrical element between the outer cylindrical element and the inner cylindrical element, wherein the first longitudinal element and the second longitudinal element are adjacent to one another and are attached to one another at one or more positions distributed along a length of the first longitudinal element and the second longitudinal element by one or more fracture element; and
fracturing the at least one fracture element by a relative movement of the first and second longitudinal elements along the length of the first longitudinal element and the second longitudinal element.
2 . The method according to claim 1 , wherein fracturing the at least one fracture element by the relative movement of the first and second longitudinal elements, includes developing an actual fracture element stress in the at least one fracture element, an actual first longitudinal element stress in the first longitudinal element, and an actual second longitudinal element stress in the second longitudinal element, wherein: the actual fracture element stress is larger than or equal to an ultimate tensile stress of the at least one fracture element, the actual first longitudinal element stress in the first longitudinal element remains lower than a first yield stress of the first longitudinal element, and the actual second longitudinal element stress in the second longitudinal element remains lower than a second yield stress of the second longitudinal element.
3 . The method according to claim 2 , wherein the at least one fracture elements is configured and arranged such that once the actual fracture element stress is equal to the ultimate tensile stress in each one of the at least one fracture element as caused by the relative movement of the first and second longitudinal elements, then the actual first longitudinal element stress in the first longitudinal element is less than or equal to a product of a parameter α and the first yield stress, and the actual second longitudinal element stress in the second longitudinal element is less than or equal to a product of the parameter α and the second yield stress, where 0.01<α≤0.8.
4 . The method according to claim 3 , wherein 0.01<α≤0.5.
5 . The method according to claim 1 , including causing the relative movement of the first and second longitudinal elements by moving one of the at least one actuation proximal zones.
6 . The method according to claim 5 , wherein the moving of the actuation proximal zone is transferred to an associated flexible distal zone of the at least one flexible distal zone via at least one of the first longitudinal element or the second longitudinal element.
7 . The method according to claim 1 , including the fracturing of the at least one fracture element when incorporating the intermediate cylindrical element between the inner and outer cylindrical elements.
8 . The method according to claim 1 , wherein the at least one fracture element comprises a first bridge part attaching the at least one fracture element to the first longitudinal element and a second bridge part attaching the at least one fracture element to the second longitudinal element, and wherein the fracturing of the at least one fracture element includes fracturing at least one of the first bridge part or the second bridge part.