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dissolvables industry: The polymers have such low melting points that before the newer generation of ultrafast, pico- and femtosecond pulsed lasers were available and reliable, scaled production was all but impossible. Chui said proper process techniques—moving the laser beam quickly and using the right assist gas, if necessary, to cool the work area and remove debris in the form of a vapor plume—are critical.


And while laser makers tout elimination of postprocessing,


there are no guarantees: “Almost nobody wants to post- process bioabsorbable stents, because by their very nature they’re very susceptible to their environment,” said Capp. Cost, Size and Speed


Just like their slower cousins, ultrafast, pulsed lasers have


their pros and cons, including cost considerations, size, and processing speed. Not surprisingly, each technology has its proponents and critics.


While costs have come down, there’s a big jump in price


from nanosecond lasers to the ultrafast, pulsed picosecond and femtosecond lasers, said consultant Stock. How big a jump? The newer type lasers are about 10 times the cost of nanosecond lasers, she said. Darren Kraemer, president of Attodyne Inc., a Toronto- based picosecond laser maker, said: “The reason they are typically more expensive than their nanosecond cousins is because of additional components.”


For example, Kraemer said, a femtosecond laser’s added chirp pulse amplifi er stretches a short pulse and then com- presses it, an unnecessary step in his view. “With a picosecond laser you don’t need to stretch and


compress,” he said. “As long as your laser pulse is less than 10 picoseconds, it doesn’t make a big difference.” In addition, Attodyne has reduced the cost of its pico- second lasers by using the best of fi ber-based and diode- pumped, solid-state technology without a lot of extra compo- nents that drive up price. Weiler agrees that the cost for the faster lasers will always be higher due to additional components needed to create the pulse; however, he has a strong rationale for why his com- pany uses them anyway. “Yes, the equipment may be more expensive, but due to the savings you get from [eliminating] postprocessing, the cost is actually lower [per part],” he said. Also on the upside, ultrafast, pulsed lasers are more compact (especially fi ber-based ones) and more effi cient (especially fi ber-based, which are 10% more effi cient than crystal-based lasers, said Stock). The size of a femtosecond


This bioresorbable PLGA stent, with a 200-micron strut width, was fabricated with a Spectra-Physics Spirit femtosecond laser.


laser, for instance, has gone down from that of an old-fash- ioned luggage trunk to about the size of an inkjet printer, she said. The smaller size is important when it comes to issues related to integrating the laser into a closed platform for industrial use.


The fastest lasers are also quite versatile. “They basically can work with any material,” said Stock. Ironically, however, processing stents with an ultrafast, pulsed laser requires patience. “It goes pretty slowly,” said Stock. “You’re just taking little bites.” That can be a problem because, “When you’re manufacturing anything, speed is important.” Weiler agrees that speed is important, but said the new technology has caught up: As recently as three years ago, manufacturing with fi ber lasers was two to three times faster than with the new, ultra-quick machines, “but now they’re the same speed or even faster.”


Capp, meanwhile, insists that cutting a nitinol stent would take longer on the ultrafast pulsed systems, perhaps three to fi ve times longer than the traditional Nd:YAG or fi ber-laser system. But the beauty of eliminating postprocessing has Laserage customers asking that their stents be cut on the newer technology.


“I tell them no,” he said. “The little bit of money you save on postprocessing isn’t worth it.”


57 — Medical Manufacturing 2015


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