MorphSkin: Adaptive Sensorised Skin for Upper Limb Prosthetics

义肢是恢复失去的功能和改善上肢差异（ULDs）患者生活质量的有价值的工具，例如截肢。然而，超过50%的UL假体被拒绝，通常是由于缺乏耐用性和机械坚固性，以及不舒服。增加耐用性和坚固性将增加假体UL的使用寿命，降低维护成本。残肢（RL）在窝内移动（引起界面压力）和RL体积变化[3]会对舒适度产生负面影响。设计改进，以提高耐用性和机械坚固性，包括顺应/可折叠的手指[4]，集成更柔软的材料减震[5]，以及防尘/防水设计[4]。不幸的是，这些解决方案只适用于温和或中等强度的活动，而不是运动。一种改进可能是使用人造皮肤，随着时间的推移改变硬度来保护UL外部，变硬以减少皮肤损伤或变软以增加减震。与此同时，假体/关节窝不适解决方案包括关节窝设计改进（例如，集成硅胶[6]，可调节压力腔[7]）和感应式关节窝来量化患者不适[3]。然而，硅胶不能改变材料刚度来优化RL压缩/缓解（减少磨损风险，同时提供安全的肢体-插座连接），压力室和嵌入式传感器在机械上不适合日常磨损。一种改进可能是基于人造皮肤的假体衬垫，它可以改变RL周围的刚度来施加或减轻压力（分别通过随着时间的推移变硬或变软）。此外，如果使用传感器人造皮肤（特别是那些没有现成传感器的人造皮肤，例如[8]）作为衬垫，则增加的机械稳健性将使用户和假肢医生更能了解用户的不适。如果将这些集成到假肢UL外观中，将使用更少的现成组件，从而降低损坏嵌入式传感器的风险。该项目的一个联合解决方案是将感应人造皮肤集成到UL假肢和插座衬垫中，随着时间的推移，它们可以通过与环境的被动接触而变硬或变软，从而提高机械的坚固性、耐久性和舒适性，具体取决于所使用的材料和刺激。首先，NeatSkin软传感器[8]将被改造成可感知的人造皮肤。NeatSkin通过微流体通道的电阻抗变化来测量变形，即电阻抗断层扫描。这种方法避免了现成的传感器，并且可以测量肢体周围的变形，以插座衬垫的形式，或者与假肢集成时与环境的相互作用。然后，感应人造皮肤将与可以“变形”的元素集成，即材料或表面根据与环境的相互作用而变硬或变软的能力，类似于生物组织和皮肤对环境的反应。最后，“变形”功能将集成到NeatSkin中，形成“MorphSkin”，并在假肢ULs和插座衬垫中进行测试。

Prosthetics are a valuable tool to restore lost functionality and improve quality of life of those with Upper Limb Differences (ULDs), such as amputations. However, over 50% of UL prosthetics are rejected [1],commonly due to the lack of durability [1] and mechanical robustness, as well being uncomfortable [2].Increased durability and robustness would increase the life span of a prosthetic UL, reducing upkeepcosts. Residual limb1 (RL) movement within the socket (causing interfacial pressures) and RL volume changes [3] can negatively affect comfort. Design improvements to increase durability and mechanical robustness include compliant/foldable fingers [4], integrating softer materials for shock absorption [5], and dust/water resistant designs [4]. Unfortunately, these solutions only aide gentle or moderately intense activities, not sports for example. One improvement could be using artificial skins that change stiffness over time to protect UL exteriors, stiffening to reduce skin damage or softening to increase shock absorption. Meanwhile, prosthetic/socket discomfort solutions consist of socket design improvements (e.g., integrating silicone [6], adjustable pressure chambers [7]), and sensorised sockets to quantify patient discomfort [3]. However, silicone cannot change material stiffness to optimise RL compression/relief (reducing abrasion risks while providing a secure limb-socket connection), andpressure chambers and embedded sensors are not mechanically robust to daily wear. One improvement could be an artificial skin-based prosthetic liner that could change stiffness to apply or relieve compression (by stiffening or softening over time, respectively) around the RL. Additionally, if using sensorised artificial skins (especially those without off-the-shelf sensors e.g., [8]) for the liner, the increased mechanical robustness would give users and prosthetists a more contextual, in situ understanding of user discomfort. If these were integrated into prosthetic UL exteriors, fewer off-the-shelf components would be used, decreasing the risk of damaged embedded sensors. A joint solution, the aim of this project, is to integrate sensorised artificial skins into UL prosthetics and socket liners that could stiffen or soften through passive contact with the environment over time, improving mechanical robustness, durability, and comfort, depending on the materials and stimulation used.Firstly, the NeatSkin soft sensor [8] will be adapted into a Sensorised Artificial Skin. NeatSkin measures deformations as changes in electrical impedance of microfluidic channels, i.e. Electrical Impedance Tomography. This approach avoids off-the-shelf sensors and can measure deformations around the limb in the form of a socket liner or interactions with the environment when integrated with the prosthetichand. The Sensorised Artificial Skin will then be integrated with elements that can 'morph', i.e., the ability of a material or surface to stiffen or soften in response to interactions with the environment, similarly to how biological tissue and skin respond to the environmental [9] [10]. Finally, the 'morphing' feature will be integrated into the NeatSkin to form the 'MorphSkin' and tested in prosthetic ULs and socket liners.