Collaborative Research: Microengineered electroactive polymer strain sensors towards soft self-powered wearable cyber-physical systems

最近的研究工作强调了软应变传感器在生物工程、康复和医学、软机器人和人机交互等各种应用中的重要作用。当前的软应变传感器通常需要外部电源才能运行，这严重限制了使此类传感器重量轻、穿着舒适、能够长时间工作的可能性。另一方面，现有的自供电传感器，如压电陶瓷，通常非常坚硬，不可拉伸，并且仅限于极小的变形。因此，迫切需要确定一种结合自供电行为和软机械特性的新型传感系统。这项研究将导致下一代软的、自供电的、高灵敏度的聚合物应变传感器的发展，用于新型生物医学和软机器人的努力。一旦成功部署，这些传感器可以嵌入到智能手套中，用于中风或帕金森病患者的手部康复，也可以嵌入到假肢设备或人机界面的仪器套件中，或者可以嵌入到可穿戴的贴片中，并与智能手机和互联网连接，以实现对生命体征的持续远程个人健康监测。此外，该项目将导致发现新的电活性材料系统，促进先进制造和机电一体化的进步，并使多物理场建模社区受益。这项研究将支持和影响研究生和本科生的教育，有助于形成下一代研究人员、工程师和教育工作者。将通过教育和外展活动争取代表性不足的学生积极参与。该项目旨在建立一类具有优越多物理场特性的新型电活性材料，用于网络物理系统中的软、自供电、高灵敏度应变传感器。离子聚合物金属复合材料是电活性软复合材料，其包括薄的带电聚合物膜，镀有贵金属电极，并注入带电溶液。由于其结合了自供电传感器行为和软机械特性，离子聚合物金属复合材料成为软应变传感器应用的理想候选者。然而，聚合物-金属界面形态的不一致和不可控带来了灵敏度有限、性能控制差和操作模式不通用的挑战。到目前为止，这些挑战限制了这些材料在关键工程应用中的使用。假设通过定制3d结构微工程聚合物-金属界面可以显著增强离子聚合物-金属复合材料的多物理场传感性能。为了验证这一假设，本研究将开发一种结合化学还原和喷墨打印的新型制造工艺，以制备具有微工程界面的离子聚合物金属复合材料。这些界面负责响应机械刺激及其随后的电化学转导和传感性能而产生的不均匀应变。本研究的主要目标是全面了解微工程离子聚合物金属复合材料的结构-性能关系，这些关系决定了增强的应变传感性能。这一目标将通过整合理论多物理场建模和实验努力，以及通过协同研究人员在智能材料和系统、先进制造、传感系统、机电一体化和控制建模方面的互补专业知识来实现。该项目将阐明聚合物电极界面在形成系统的化学机电响应中的作用，并形式化实验验证的模型，该模型结合界面形态信息来预测多物理场传感特性。所提出的传感系统的潜力将通过设计、制造和在软机器人和人机交互研究的实验平台上测试功能传感器来证明。通过该项目获得的知识将显著推进对高性能传感系统开发的电活性材料的理解状态。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Recent research efforts have emphasized the vital role of soft strain sensors in a variety of applications in bioengineering, rehabilitation and medicine, soft robotics, and human-machine interactions. Current soft strain sensors often necessitate external power for operation that severely limits the possibility to make such sensors light weight, comfortable to wear, and capable of functioning over long periods of time. On the other hand, existing self-powered sensors, such as piezoelectric ceramics, are typically very stiff, non-stretchable, and limited to extremely small deformations. Thus, there exists a clear and urgent need to identify novel sensing systems that combine self-powered behavior with soft mechanical characteristics. This research will result in the development of the next generation of soft, self-powered, high sensitivity polymer-based strain sensors for applications in novel biomedical and soft robotics endeavors. When successfully deployed, these sensors could be embedded in smart gloves for use in hand rehabilitation by patients suffering from stroke or Parkinson's disease, as well as an instrumentation suite for prosthetic devices or in human-machine interfaces, or could be embedded in wearable adhesive patches and interfaced with smartphones and the internet for continuous remote personal health monitoring of vital signs. Furthermore, this project will lead to discover novel electroactive materials systems, promote advancements in advanced manufacturing and mechatronics, and benefit the multiphysics modeling community. This research will support and impact the education of graduate and undergraduate students, contributing to the formation of the next generation of researchers, engineers, and educators. Active involvement of underrepresented students will be pursued via educational and outreach activities. This project aims at establishing a new class of electroactive materials with superior multiphysics properties towards soft, self-powered, high sensitivity strain sensor applications in cyber-physical systems. Ionic polymer metal composites are electroactive soft composite materials that comprise a thin electrically charged polymer membrane, plated with noble metal electrodes, and infused with a charged solution. Due to their combined self-powered sensor behavior and soft mechanical characteristics, ionic polymer metal composites emerge as an ideal candidate for soft strain sensor applications. However, inconsistent and uncontrollable morphology of their polymer-metal interfaces poses the challenges of limited sensitivity, poor property control, and non-versatile mode of operation. So far, these challenges have limited the use of these materials in critical engineering applications. It is hypothesized that the multiphysics sensing properties of ionic polymer metal composites can be dramatically enhanced by tailored 3D-structured microengineered polymer-metal interfaces. To test this hypothesis, this research will develop a novel fabrication process integrating electroless chemical reduction with inkjet printing to prepare ionic polymer metal composites with microengineered interfaces. These interfaces are responsible for inhomogeneous strain developed in response to a mechanical stimulus and its subsequent electrochemical transduction and sensing performance. The main goal of this research is to gain a comprehensive understanding of the structure-property relationships in microengineered ionic polymer metal composites that determine enhanced strain sensing performance. This goal will be achieved by integrating theoretical multiphysics modeling and experimental efforts and by synergizing the investigators' complementary expertise in modeling of smart materials and systems, advanced manufacturing, sensing systems, and mechatronics and controls. This project will elucidate the role of polymer-electrode interfaces in shaping the chemoelectromechanical response of the system and formalize experimentally validated models that incorporate interface morphology information to predict multiphysics sensing properties. The potential of the proposed sensing system will be demonstrated by designing, manufacturing, and testing functional sensors in experimental platforms for studies on soft robotics and human-machine interaction. The knowledge gained through this project will significantly advance the state of understanding of electroactive materials towards development of high performance sensing systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.