Functionally graded shape memory alloy (SMA) micro-actuators for neurosurgical applications

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This project will focus on the development of (predominantly) laser-based manufacturing processes to fabricate micro-actuators based on the Shape Memory effect, which can provide a high energy density movements controlled e.g. by remote heating. Nickel-titanium SMA has found many applications in medical devices due to its excellent biocompatibility coupled with its ability to change shape significantly (to a pre-programmed, i.e. memorised, state) as it crosses a transition temperature (that can be tuned by varying the alloy composition and thermomechanical treatment) close to body temperature. The particular application of interest in this project is as a switch for fluid delivery that can be remotely actuated, for prolonged treatment of brain tumours with permanently inserted catheters. The concept is a shape memory alloy valve that can be switched via remote heating e.g. by using infrared light (if close to the skin) or radio energy transfer. Laser-based manufacturing processes, including micro-welding and micro-cutting will be used to fabricate the devices with minimal heat input, to prevent unwanted changes to the remaining material properties. We have well-established expertise in these processes supported by extensive facilities. In addition, we have recently developed a modification of the laser induced forward transfer (LIFT) process for manufacturing more complex composite SMA parts which can be included into the overall design and manufacturing process.