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

该项目将专注于开发（主要）基于激光的制造工艺，以制造基于形状记忆效应的微致动器，该微致动器可以提供高能量密度的运动，例如通过远程加热控制。镍-钛SMA在医疗器械中有许多应用，这是由于其优异的生物相容性，以及当其跨越接近体温的转变温度（可以通过改变合金成分和热机械处理来调整）时显著改变形状（至预编程，即记忆状态）的能力。在这个项目中，感兴趣的特定应用是作为可以远程致动的流体输送开关，用于永久插入导管的脑肿瘤的长期治疗。该概念是一种形状记忆合金阀，可以通过远程加热进行切换，例如通过使用红外光（如果靠近皮肤）或无线电能量传输。基于激光的制造工艺，包括微焊接和微切割，将用于以最小的热输入制造设备，以防止对剩余材料特性的不必要的改变。我们在这些过程中拥有完善的专业知识，并得到广泛设施的支持。此外，我们最近开发了一种改进的激光诱导前向转移（LIFT）工艺，用于制造更复杂的复合材料SMA部件，可以将其纳入整体设计和制造过程。

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.