Laser Cutting Surgical Hypotubes

Hypotubes：一项挽救生命的科技

Minimally invasive surgery offers many advantages and hypotubes (sometimes called guidewires) are critical devices used in many of these medical procedures. These hypotubes need to be small and flexible in order to fit inside human blood vessels. And they need to be hollow to allow for the control of tools or the delivery of drugs.

微导管必须满足多项复杂要求。其边缘必须无毛刺，所用材料应具备柔韧性且易于灭菌。导管远端的设计可从简单的切口到复杂的微加工组件。为确保可靠操作，微导管在承受一定扭矩时应保持柔韧性，同时必须耐受弯折和推挤。

The flexibility of a metal hypotube is achieved through a pattern of cuts in its walls. An interrupted spiral pattern is one way to achieve this. The length of the incisions and the pitch between the cuts define the remaining stiffness of the tube. The precision of the cuts is crucial for ensuring the correct behavior of a hypotube during surgical procedures.

精密高效的微管加工

Typically, hypotubes are processed with advanced laser technology. The laser systems must perform different tasks, such as marking, cutting, and drilling on or in the wall of a metal tube. Currently, a medium-power fiber laser is the gold standard for these tasks. All edges must be burr-free, which can require some post-processing steps after the laser.

However, a growing number of users now choose a femtosecond laser instead of a fiber laser. Such an ultrashort pulse (USP) laser deposits its energy into the material so rapidly that the heat cannot spread, and the heat-affected zones are minimized when the material is vaporized. Thus, USP lasers create relatively smooth edges where post-process water cleaning is often sufficient. Conversely, USP lasers, while being extremely precise, are somewhat slower than fiber lasers.

A sample hypotube processed with the Coherent StarCut Tube is shown in figure 1. For demonstration purposes, a StarCut Tube Hybrid with both a fiber laser and a femtosecond laser was used. A StarCut Tube SL with just a fiber laser or a femtosecond laser can solve the task as well, while possessing a smaller footprint.

The sample was cut out of a stainless-steel tube with an outer diameter of 0.7 mm. The tube has a wall thickness of 100 µm. On the left end, a so-called skive was cut out. A small test slit was excised within the skive. Additionally, two black rings were marked on the hypotube. These three steps were all executed with a Coherent Monaco femtosecond laser.

A sample hypotube processed with the Coherent StarCut Tube is shown in figure 1. For demonstration purposes, a StarCut Tube Hybrid with both a fiber laser and a femtosecond laser was used. A StarCut Tube SL with just a fiber laser or a femtosecond laser can solve the task as well, while possessing a smaller footprint.

The sample was cut out of a stainless-steel tube with an outer diameter of 0.7 mm. The tube has a wall thickness of 100 µm. On the left end, a so-called skive was cut out. A small test slit was excised within the skive. Additionally, two black rings were marked on the hypotube. These three steps were all executed with a Coherent Monaco femtosecond laser.

In the next step, a long, interrupted spiral was cut into the tube’s wall. For this process, the system switched to the second laser source of this hybrid workstation: a Coherent PowerLine FL with moderate power. The spiral pattern was cut “on-the-fly,” i.e., while the tube was moved constantly at high speed. During this process, the timing of the laser was triggered precisely for the start of each cut.

图2展示了光纤激光加工的结果。 低压管轴体存在两种典型加工纹理：间断螺旋纹或称砖砌纹。砖砌纹由平行排列的间断刻痕构成，形似砖墙砌块。典型低压管长约1.5米，采用飞行切割工艺可实现管体长段的高速加工。本样品的加工周期仅需35秒。