Top 4 Uses of Lasers in Medical Device Manufacturing

Laser technology is used for a wide range of medical device manufacturing processes, including marking, micro-welding, cutting, micromachining and more; they are the veritable Swiss Army® Knives of manufacturing. This post will explore what we consider the top 4 uses of industrial lasers in medical device manufacturing and the laser sources most appropriate and effective for each process.

1. Laser marking – great for company and product/part information and traceability

Laser marking is used for a wide range of medical and dental devices including bone screws, cases which house delicate electronics like pacemakers and auditory implants and endoscopic tools. Well known as an excellent way to permanently mark company and product/part information to ensure traceability, laser marking is a direct part marking (DPM) process ideal for achieving the corrosion-resistant unique device identifier (UDI) marks mandated by the FDA.

There are several different laser sources suitable for laser marking, which are categorized based on wavelength, laser medium, or pulse duration. These include ultraviolet (UV), green, infrared (IR), far infrared (FIR) and ultrashort pulse (USP) picosecond and femtosecond lasers. Material selection will determine which laser source is best suited for the project.

One interesting growing trend is the use of stainless steel multi-use medical devices, where mark must be:

• Corrosion-resistant
• Free of surface inclusions
• Biocompatible
• Able to survive multiple cleaning passes

We have found that USP lasers achieve the best overall results and pass a rigorous hot nitric acid test (insert maniacal “Doctor Evil” laugh), with special recipes developed for 17-4, 17-7, 304 and 316 stainless steel alloys. Another interesting black, corrosion resistant marking application for USP lasers is banding – essentially marking tubes with depth gradations.

2. Laser welding – ideal for joining very small, intricate parts

Lasers are widely used for spot welding, seam welding and hermetic sealing of small, intricate medical devices. We’re talking really small. Laser micro welding is defined as a weld where the penetration and weld width is under 1 mm. Micro welds like this are often used for pacemakers, surgical blades, endoscopic instruments and batteries.

There are a variety of laser sources suitable for micro welding, including pulsed Nd:YAG, continuous wave (CW) fiber, nanosecond (Ns) fiber, quasi continuous wave (QCW) fiber and high brightness direct diode (HBDD) lasers. Once again, your application will determine the most appropriate laser source.

Spot welding of medical tubes and the electrical contacts for fine springs, hook assemblies, guidewires, and medical hypo wires requires precision energy delivery and tooling:

• 20-200 micron spots → fiber lasers
• 200-1000 micron spots → pulsed Nd:YAG lasers

Seam welding, the method used for seam-sealed implantable devices, can be achieved with pulsed Nd:YAG or CW lasers. Here the deciding factor may be the complexity of the geometry and part sensitivity to heat.

Pulsed nanosecond (Ns) lasers – fiber lasers – employed for medical device manufacturing relatively recently, are a great choice for welding very small parts with metal thicknesses up to 0.25 mm and spot sizes <50 micron. Pulsed Ns lasers can join nearly any material combination, opening up new opportunities for small components and new material combinations.

3. Laser cutting – precision cutting for shaver blades, shafts, cannulas and hypo tubes

Laser cutting is uniquely suited to cutting arthroscopic shaver blades, flexible shafts, stents, cannulas and hypo tubes, as well as hypodermic needles.

Laser cutting is generally segregated into two methods:

• Gas assist cutting which is usually used in conjunction with a microsecond laser source.
• Ablation, which typically utilizes a nanosecond, picosecond, or femtosecond laser source to fire on the part with immediate ejection of material without any post processing and minimal heat affected zone.

Gas assist cutting is the most common method for laser cutting medical tools. The speed and precision is sufficient for excellent cut quality and kerf width. However, as the tube diameter and features become smaller, it becomes necessary to move to an ablative technique using pulsed lasers. This technique can achieve feature sizes and kerf widths on the order of 10s of microns.

4. Laser micromachining – precise surface structuring and hole drilling

Laser micromachining is used in medical device manufacturing for surface texturing and drilling holes in needles, catheters, implantable devices and micro instruments. USP (ultra-short pulse) lasers are typically used in these applications because the short pulse duration enables the removal of the material far more efficiently and with less energy put into the part, resulting in clean cuts with little post-processing required.

Though not a particularly fast process, laser micromachining is extremely precise, making it an especially good choice for surface texturing of polymer catheter tubes. For this application, a femtosecond pulsed laser delivers the precise texture depth control and highly consistent structures required.

USP lasers can also drill extremely precise small (80-200 microns) holes into needles. In addition, the laser system can be programmed to machine holes of circular, square, or oval shapes to help control drug delivery through the needle. The laser can also create different types of structures in different materials, including metals, polymers, ceramics and glass.

Another key micromachining application is wire stripping. In this application, selective ablation is achieved using a femtosecond green laser to remove polyurethane coatings with thicknesses up to 20 microns – with no damage to the underlying material.

In summary, lasers are used in a variety of processes for manufacturing medical devices. Each process requires a different laser source, but generally the optimal solution can be found. AMADA WELD TECH provides free feasibility of processes in the technologies listed above. With 10 application labs and 10 full time application engineers, AMADA WELD TECH is ready to test your samples and provide advice on the laser selection and process tips.