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The surface quality of coronary stents has a significant influence on its biocompatibility. Therefore, surface polishing is of paramount importance in the production and application of stents. In the present study, electropolishing is performed on 316LVM steel slotted tube coronary stents. Additionally, acid pickling, as a pretreatment of electropolishing, is also conducted. Gravimetric analysis of the stents (weight loss and strut width change) in the process of acid pickling and electropolishing are done. Qualitative roughness measurements are made to evaluate the stent surface. Electropolished stents are passivated causing chromium enrichment on the surface of the material, thereby enhancing its corrosion resistance. Passivated and electropolished samples are examined using energy dispersive spectrometry. Balloon expanded and crimped profiles of the passivated stents are qualitatively analyzed.

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Photonics modulation techniques can be effectively used for the laser microfabrication of biomedical implants to achieve better flexibility and control of the available optical power. These enable the processing and manufacturing of biomedical implants like cardiovascular stents and micro-metallic components with reduced heat affected zone ͑HAZ͒ and extremely precise edge cutting. Our investigation deals with the study of acousto-optic modulation of a pulsed Nd:YAG laser beam and further profile cutting of thin cobalt-chromium tubes for cardiovascular stent manufacturing. The acousto-optic modulator used in the investigations is a Bragg diffraction device. During one piercing process, the focused laser power is gradually varied from a low value and reaches the maximum as the beam goes deeper into the material. The optimum value for dwell time during which the laser piercing is occurring is found as 58 ms. A 14-step staircase modulating voltage with a maximum AC component of 900 mV was used, and the laser power was 4.4 W in TEM 00 operation. Pulsed Nd:YAG laser modulated using an acoustooptic device in the Bragg regime is capable of cutting extremely complex geometries of stents on L605 tubing. Laser cutting resulted in a kerf width of 22.5± 0.5 m. Precise strut dimensions of 112± 15 m for the subsidiary strut, 140± 15 m for the main strut, and 140± 15 m for the link were also obtained. Scanning electron microscopy ͑SEM͒ images of L605 stents illustrate the higher strength Co-Cr alloy L605 with the same ductility, its ability to be translated into thinner struts, and improved deliverability. L605 also exhibits enhanced radio visibility thanks to its tungsten content and exceptional work hardening rate for a uniform expansion with minimal recoil.

Laser Raman spectroscopy is an effective tool for the study of biodegradable polymers, which play a vital role in the new developments in coronary implants such as stents. There is much excitement around the potential capabilities of synthetic biodegradable polymers and the effect they will have on the design and function of implanted devices. In the present investigation, heparin-conjugated biodegradable copolymers were evaluated for their durability as drug-eluting stent coatings. Laser Raman spectroscopic studies were carried out and spectra recorded and analyzed of explanted stents coated with different amounts of polymer alone, showing the existence of different levels at different quantities of polymer. The polymer was detected on every stent analyzed. On the stents coated with a thick layer of polymer, a firm layer of polymer still existed on the stent. In contrast, this layer was degraded and spread around on the stents coated with only a thin layer of the polymer. This indicates that the polymers used in the stents in the present investigation exhibit acceptable biodegradability. Such polymers can be used as efficient drug carriers, as these materials show good degradation after the stipulated period.