MEDICAL DEVICES
Stent manufacturing is one of the biggest applications of laser technology in medical device manufacturing “USP lasers
minimise the heat- affected zone on the workpiece, resulting in a reduction in detrimental effects”
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absolutely critical for maintaining the biocompatibility of materials destined for implanting. If vascular stents are machined via a continuous-wave laser or a pulsed nanosecond or picosecond laser, the biopolymer material can become bio-toxic as it heats up and its chemical composition alters. By contrast, femtosecond lasers limit such thermal effects as they transfer minimal heat to the material. Another advantage of
femtosecond lasers is that post processing after cutting the stent is minimised. This is because using lasers with pulse durations longer than a femtosecond can cause structural damage when cutting stents made from nitinol, stainless steel and magnesium. The structural debris must then be removed via various cleaning
steps. In comparison, stents cut using femtosecond lasers – which give very good details and edges – only need to be put in an ultrasonic bath before use, thereby removing multiple processing steps and saving production time. For fabricating medical
devices that need to deliver fluids very precisely such as annulae, catheters (some of which are made from polyether ether ketone (PEEK)) and needles, femtosecond lasers are also a favoured tool. For metal versions of these devices the rapid femtosecond pulses prevent re-melting of the surface and consequent changes in structure, while their use avoids toxicity and structural damage in polymers. The latter is particularly important for devices containing laser machined slots or holes through which drugs need to be delivered; these must be extremely accurate and repeatable to enable the required high controllability of flow needed for drug delivery.
Component and implant manufacturing Femtosecond lasers are also increasingly being used to open and clean the metal wire
26 LASER SYSTEMS EUROPE THE 2023 GUIDE TO LASER SYSTEMS
contacts on implantable devices, and micro-weld medical device components. They are equally ideal for machining holes known as ports into glass biopsy probes with diameters from 12µm to over 20µm. These ports are between 5µm and 10µm in size, and have sharp edges that need to be drilled through the sidewall near the probe’s tip. Laser additive manufacturing of bone implants is another application in which the use of lasers is being investigated. Such lasers could enable implants to be readily tailored to individual patients, and allow shapes to be made that are impossible to fabricate using standard manufacturing techniques. Lasers can also be used to
roughen the surfaces of some implantable devices to help them integrate within the body via improving the bone ingrowth (osseointegration). In particular, it is ultrafast lasers that are holding promise for modifying the surfaces of implants to enhance osseointegration. Currently, grain blasting followed by acid etching is used to create a surface that bones cells can grow more readily on. But these techniques are not optimal, as they can leave behind residues and impurities which reduce the overall gain in the amount of osseointegration. Ablating using ultrashort pulsed lasers leave no residue – and, unlike other types of laser, ultrafast lasers minimise surface melting and vapourisation
Ultrafast laser manufacturer Fluence’s femtosecond lasers can be used to drill tiny holes in microfluidic medical devices
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Shutterstock/Christoph Burgstedt
Fluence
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