Lasers & photonics
biomedical filters, heart valve components and pacemaker components. All these devices are shrinking and becoming more complex because laser micromachining can introduce smaller features, which allows the overall device size to be minimised. Of all the smaller implantable medical devices now possible with laser micromachining, the area that has benefitted the most is stents. Stents have been getting increasingly complex as more procedures are performed each year. Many early stents used to end up covered in scar tissue, rendering them ineffective. Efforts since have used biodegradable polymer coatings to prevent this, but now laser micromachining is being used to create stents that are inherently biocompatible based on their surface features – which reduces the risk of arterial narrowing after surgery (restenosis). It is important to note that biocompatibility is also influenced by material selection and any coatings applied; laser micromachining enhances surface characteristics but works alongside these other factors to improve overall performance.
Devices enabled by micromachining Many stents – especially drug-eluting stents – need to be smaller to be placed in smaller blood vessels. Laser micromachining is not only helping to create stents with smaller tube diameters and more complex features, but its versatility is enabling stents to be made from a wider range of materials. For enabling smaller stents, other techniques have struggled due to the induced HAZ causing damage, but that’s no longer an issue.
Basha states that “laser micromachining can introduce micro-perforations for drug delivery or fluid control in stents and catheters, while fabricating surface nanotextures in metal and polymer stents enhances cell adhesion, drug retention and biocompatibility, while reducing bacterial colonisation”. On top of the stents themselves, laser micromachining can be used to fabricate very small and structure- specific membranes that act as an arterial filter to stop any broken pieces from entering the vessels during surgery and causing further complications (such as a potential stroke). But it’s not just stents, various catheters are being improved by laser micromachining. It is being used to introduce micro-perforations into fibre-optic catheters, which helps with regulating fluid delivery and embedding sensing features (something that is a future direction for catheters). These micro-perforations are carefully designed to control fluid flow or enable sensing functions, ensuring precise delivery of therapeutic agents or accurate measurement of physiological parameters. For the surgical procedures themselves, photonic-bandgap fibres can be used in flexible surgical instruments to
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enable minimally invasive cutting with minimal thermal damage, which can then be followed up by the cauterisation of tissue using laser micromachined cryogenic catheters.
While they are not a minimally invasive device per se, laser micromachining is also helping to create sharper surgical tools used during these procedures by introducing sharper contours that enable a cleaner cutting of the skin. On the diagnostic and testing side that runs alongside minimally invasive surgery, microfluidics and lab-on-chip diagnostic platforms are also being improved because smaller channels can be made smooth and burr-free with more precise cutting, leading to smaller diagnostic platforms being created and lab-on-a-chip platforms that have more channels per area.
The future of laser micromachining There are already many examples of laser micromachined minimally invasive devices in use today. “Laser-cut stents, micro-perforated catheters and microfluidic diagnostic chips are already in global clinical use,” says Basha. “More advanced devices – such as bioresorbable laser-textured implants and sensor-integrated catheters – are progressing through trials. Regulatory approvals are stringent, but the reproducibility and cleanliness of laser processes facilitate compliance.” It’s also likely that the future of laser micromachining will involve some level of artificial intelligence (AI) integration for real-time optimisation of the fabrication process. “The next evolution will combine ultrafast laser micromachining with AI-driven process control and inline inspection. This integration will enable scalable, high-throughput production of complex, patient-specific devices,” states Basha, concluding that “we’re moving towards a future where the laser system doesn’t just machine – it thinks, inspects and validates every feature in real time”. While the developments in laser micromachining are now widely implemented, it is not the only new manufacturing innovation that is being used to create minimally invasive devices. 3D printing has now become a widely used manufacturing technique for making small implants with complex geometries and optimised surface properties (such as a specific surface roughness to promote cell adhesion and osseointegration). However, it is seen as a complementary technique – not a competitive technique.
Basha captured the interplay between 3D printing (additive manufacturing) and laser micromachining very well, “Additive manufacturing can form the complex 3D structure of a medical device, and laser micromachining refines and functionalises it. Think of additive manufacturing as building the house – laser micromachining is the precision interior finishing.” ●
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