Laser-activated SMP devices are a unique combination of laser-tissue and biomaterial technologies. Successful deployment of the microactuator requires well-engineered coupling of the light from the diffusing fiber through the blood into the SMP.

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We present interventional devices for treating ischemic stroke. The development and testing of two complementary devices is proposed a mechanical clot extraction system and a neurovascular stent. These devices are laser-activated shape memory polymer microactuators. Paper SummaryThe National Institutes of Health recently awarded a Bioengineering Research Partnership Grant for "Shape Memory Polymer Devices for Treating Stroke," which is a partnership between Lawrence Livermore National Laboratory (lead institution) and two departments at UC Davis (Immunology and Radiology). The development and testing of two complementary devices was proposed a mechanical clot extraction system and a neurovascular stent. The clot extraction system will address the current clinical need for an acute ischemic stroke treatment and the stent will address the chronic problem of stenosis and/or restenosis of the neurovasculature. Both of these devices utilize photomechanical micro-actuators based on laser-activated shape memory polymer (SMP).SMP is a material that will have a significant impact on clinical medicine. SMP is a relatively new material that is similar to shape memory metals in its ability to actuate from an initial deformed shape into a second, pre-determined shape. Shape memory metals are currently very popular in medicine as a material for making vascular stents. SMP bas advantages over shape memory metals for certain applications, including cost, higher recoverable strain levels, ease of manufacturing, better flexibility in navigating tortuous paths, and great versatility in fabricating extremely small, highly complex actuators. Potential applications of SMP include stents, stent release mechanism, embolic coil release mechanisms, thrombus extraction devices, and many others.The underlying hypothesis of this research is that mechanical devices can be used to treat stroke victims where there is currently no clinical alternative. There are five known private companies that are currently pursuing this hypothesis for the acute ischemic device and an unknown but presumed large number of companies pursuing neurovascular stents. Members of the current proposal team originally developed one of the technologies that is in FDA trials for treating ischemic stroke, photo-acoustic emulsification of the thrombus. However, in our opinion, none of the current devices under FDA trials is as promising or as straightforward as the devices proposed. Further, we believe that the technology developed and published from the proposed studies will lead to many other medical applications that are far beyond the scope of one proposal and one team of investigators.The proposed research is a unique combination of biomaterials, lasers and optics, i~unology/biocompatibility and clinical interventional neuroradiology. This paper summarizes our work to date with laser-activated shape memory polymer (SMP) microactuatod2. The reported SMP devices are under development for endovascular treatment of ischemic stroke and cerebrovascular aneurysms. Stroke is a...

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Objective: In this paper the photothermal design aspects of novel shape memory polymer (SMP) microactuators for treating stroke are presented. Materials and Methods: A total of three devices will be presented: two interventional ischemic stroke devices (coil and umbrella) and one device for releasing embolic coils (microgripper). The optical properties of SMP, methods for coupling laser light into SMP, heating distributions in the SMP devices and the impact of operating the thermally activated material in a blood vessel are presented. Results: Actuating the devices requires device temperatures in the range of 65 "C-85 "C. Attaining these temperatures under flow conditions requires critical engineering of the SMP optical properties, optical coupling into the SMP, and device geometries. Conclusion: Laser-activated SMP devices are a unique combination of laser-tissue and biomaterial technologies. Successful deployment of the microactuator requires well-engineered coupling of the light from the diffusing fiber through the blood into the SMP.