3D printing of micro-scale graded shape memory components for in-vivo actuated medical devices

用于体内驱动医疗设备的微型分级形状记忆组件的 3D 打印

基本信息

批准号：
EP/T005076/1
负责人：
Duncan Hand
金额：
$ 32.24万
依托单位：
Heriot-Watt University
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2019
资助国家：
英国
起止时间：
2019 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FT005076%2F1
关键词：
3D printing micro scale graded

项目摘要

Micro-robots have great potential for evaluation and treatment of medical conditions. Such devices require highly controlled actuation at a micro-scale to provide controlled motion, testing of tissue compliance, biopsy, etc, and this is a prospect offered by functionally-graded shape memory alloys (SMAs). An SMA has the ability to "remember" its original shape and that when deformed returns to its pre-deformed shape when heated. Such alloys have sparked great interest ever since their first development. Functional grading of SMAs (i.e. locally modifying the properties of the material to tailor the SMA effect in different parts of the device) allow the design of more complex and hence much more controllable actuation mechanisms. Devices and components manufactured from functionally graded SMAs can provide actuation in response to external stimulation (stress or temperature variation, e.g. via induction heating), outperforming conventional actuation mechanisms such as electromagnets or electrical motors in terms of work output density. Such performance is ideal for micro-devices for minimally invasive medical applications such as precise incision, tissue identification, tactile sensing for disease and tweezing, as well as more ambitious shape transformations for "unpacking" structures in situ and "intelligent" stents and patches.The manufacturing challenge here is to achieve that functional grading at a micro-scale, by a combination of locally tailoring the material composition and thermal history. This will be achieved via development of a novel process, functionally graded Laser Induced Forward Transfer (FG-LIFT). This process will use a multi-track 'donor ribbon' (rather like a multicoloured typewriter ribbon) to deposit "sub-voxels" (of typical dimensions a few microns across and hundreds of nm high) of different metals, e.g. Ti, Ni and Cu onto a target substrate, in order to construct voxels each consisting of a number of subvoxel layers of different metals. By altering the laser parameters, subsequent thermal treatment will be used to provide control of interdiffusion within and between voxels providing very tight localised control of composition. 3D microstructures will hence be constructed by continuing to add additional voxels. This FG-LIFT process will be used to manufacture sub-mm and mm-scale SMA components with functional grading at a scale of 10's of microns. This highly challenging concept requires 3D control - at the micro-scale - of both material composition and thermal treatment. By depositing the functionally graded SMA material onto substrates with appropriate material properties (e.g. carbon fibre mats or trace heaters), additional tailoring of the overall performance of the device will be achieved.

微型机器人在评估和治疗医疗状况方面具有巨大潜力。此类设备需要在微观尺度上进行高度控制的驱动，以提供受控运动、组织顺应性测试、活检等，而功能梯度形状记忆合金（SMA）提供了这一前景。 SMA 具有“记住”其原始形状的能力，并且在变形后加热时会恢复到变形前的形状。这种合金自首次开发以来就引起了人们的极大兴趣。 SMA 的功能分级（即局部修改材料的属性以适应设备不同部分的 SMA 效果）允许设计更复杂、因此更可控的驱动机制。由功能分级 SMA 制造的设备和组件可以响应外部刺激（应力或温度变化，例如通过感应加热）提供驱动，在工作输出密度方面优于电磁体或电动机等传统驱动机构。这种性能非常适合微创医疗应用的微型设备，例如精确切口、组织识别、疾病和镊子的触觉传感，以及用于原位“拆包”结构和“智能”支架和补片的更雄心勃勃的形状变换。这里的制造挑战是通过结合局部定制材料成分和热历史来实现微观尺度的功能分级。这将通过开发一种新工艺、功能分级激光诱导前向转移 (FG-LIFT) 来实现。该过程将使用多轨“供体色带”（类似于彩色打字机色带）来沉积不同金属的“子体素”（典型尺寸为几微米宽和数百纳米高），例如金属。将 Ti、Ni 和 Cu 沉积到目标基底上，以构造每个体素，每个体素由多个不同金属的子体素层组成。通过改变激光参数，随后的热处理将用于提供对体素内部和体素之间相互扩散的控制，从而提供非常严格的成分局部控制。因此，3D 微观结构将通过继续添加额外的体素来构建。该 FG-LIFT 工艺将用于制造亚毫米级和毫米级 SMA 组件，其功能分级为 10 微米级。这一极具挑战性的概念需要在微观尺度上对材料成分和热处理进行 3D 控制。通过将功能梯度 SMA 材料沉积到具有适当材料特性的基板上（例如碳纤维垫或微量加热器），将实现设备整体性能的额外定制。