MorphSkin: Adaptive Sensorised Skin for Upper Limb Prosthetics

假肢是恢复丧失的功能和改善上肢差异(ULD)患者生活质量的宝贵工具，例如截肢。然而，超过50%的UL假体被拒绝[1]，通常是由于缺乏耐用性和机械稳定性，以及不舒服[2]。增加耐用性和健壮性将增加UL假体的寿命，减少维护成本。插座内残留的Limb1(RL)运动(导致界面压力)和RL音量变化[3]会对舒适性产生负面影响。提高耐用性和机械坚固性的设计改进包括柔顺/可折叠手指[4]，集成更柔软的减震材料[5]，以及防尘/防水设计[4]。不幸的是，这些解决方案只对温和或中等强度的运动有帮助，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僵硬程度以保护UL外部，硬化以减少皮肤损害，或软化以增加减震。与此同时，假肢/插座不适解决方案包括插座设计改进(例如，集成硅胶[6]、可调压力室[7])和感应式插座以量化患者的不适感[3]。然而，硅胶不能改变材料的硬度以优化RL压缩/缓解(在提供安全的肢体-插座连接的同时降低磨损风险)，并且压力室和嵌入式传感器在日常磨损中机械性能不强。一种改进可能是一种基于人造皮肤的假体衬垫，它可以改变硬度，以施加或减轻RL周围的压力(分别通过随着时间的推移而变硬或变软)。此外，如果使用感应式人造皮肤(特别是那些没有现成传感器的皮肤，例如[8])，增强的机械坚固性将使用户和修复师对用户的不适感有更多的背景和现场了解。如果将这些集成到假体UL外部，将使用更少的现成组件，从而降低嵌入式传感器损坏的风险。该项目的目标是将感应式人造皮肤集成到UL假体和插座衬垫中，这些假体和插座衬垫可以随着时间的推移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、耐用性和舒适性，具体取决于所使用的材料和刺激。首先，NeatSkin软测量[8]将被改造为感应化人造皮肤。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，并可以测量肢体周围的变形，在与假肢集成时，可以测量插座衬垫的形式或与环境的相互作用。然后，感应化的人造皮肤将与能够“变形”的元素相结合，即材料或表面因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[9][10]。最后，“变形”功能将被集成到NeatSkin中，形成“MorphSkin”，并在假体UL和插座衬垫上进行测试。

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.