EAGER: Developing and Bio-Inspired Assembly of Highly Scalable Electromagnetic Soft Actuators for Active Elbow Brace

神经受损的人，如中风患者，在活动关节时经常需要帮助。然而，目前的可穿戴康复和辅助设备要么是1)强大而活跃，但体积庞大，由外骨骼和假肢等刚性元件制成，要么是2)灵活但被动，功能有限，如关节支架。尽管软机器人技术最近取得了进展，但仍然没有便携式的软执行器（运动产生装置），即可以通过机载电源操作，可扩展以适应不同的关节尺寸，并且仍然具有辅助关节运动所需的短响应时间和高输出力与尺寸比。为了满足这一需求，该项目的目标是设计、制造和评估一种新型的电磁软致动器（ESA），它可以很容易地由车载电池供电，并且可以模仿肌肉节（基本的人体肌肉驱动单元）内收缩细丝（肌动蛋白和肌球蛋白）的行为产生线性力和收缩。ESA具有高度可扩展性，并且可以在并联和串联组装时小型化以创建人工肌节。一系列人造肌瘤将形成ExoFiber。作为主要的激活单元，每个人造肌节将分别被电刺激。然后将ExoFibers绑带嵌入到关节支撑中使其活动。exofiber是根据电磁原理激活的，可以快速通电产生力和运动。exofiber -active支架用于人类肘关节的性能将在有和没有肘部残疾的人类中进行小规模的试点研究。研究结果将通过可扩展的软致动器推进下一代灵活、强大和便携式的主动支架，用于关节运动辅助和康复应用，并将为动态系统、材料设计和康复治疗的软致动器网络设计和分析的跨学科研究奠定基础。通过开发新的软康复机器人研究生课程，并与UTSA卓越工程教育中心（CE3）和iTEC合作，让来自圣安东尼奥代表性不足群体的学生参与该项目，将实现教育和外展影响。这个探索性项目研究了制造电磁软致动器（ESA）的可能性，该装置可以由机载电池供电，可以模仿肌动蛋白和肌球蛋白在肌节内收缩的行为，产生线性力和收缩，当以生物灵感的平行和串联模式组装时，可以小型化以创建人工肌节。人造肌节可以连接到exofiber中，可以嵌入人体肘关节支架中，用于康复治疗或作为辅助设备。研究计划有两个目标。AIM 1专注于设计和制造。ESA设计由两个具有弹簧连接的对抗性螺线管和一个由软材料制成的内部铁磁核心组成。通过向微线圈中注入电流，将产生两个对立的电磁场，从而产生排斥力或引力，拉伸或压缩弹性连杆。人造肌节和ExoFibers设计将使用生物打印的esa进行组装，以方便生产。并联组装的esa数量将决定输出源，串联的esa数量定义总体收缩。AIM 2的重点是开发和评估主动支撑的动态特性，即嵌入ExoFiber的支撑。实验平台将在三个层面上进行测试：单个ExoFiber、主动支架和人体肘部。输出性能可以定义为：1)ExoFiber的收缩长度、输出力、线性刚度和带宽，2)主动支撑的屈曲范围、扭矩、角刚度和带宽，以及3)屈曲范围、人体肘部的舒适性和易用性。当支架放置在生物打印的手臂模型上时，将评估活动支架的水平。人类肘部水平将通过在两组成年人中进行小规模试点研究来评估：健康个体和肘部无力、活动范围减小或因中风而僵硬的受试者。参与者将被要求进行三种类型的练习：1)在突然受到2Nm扭矩的干扰时，以5种不同的屈伸固定角度保持手臂；2)在以两种不同的速度（慢速和正常）握住2Kg重量时弯曲和伸展手臂；3)在恒定的2Nm扭矩下弯曲手臂。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。

Neurologically impaired people such as stroke patients often need assistance in moving their joints. However, current wearable rehabilitation and assistive devices are either 1) powerful and active but bulky and made of rigid elements such as exoskeletons and artificial limbs, or 2) flexible but passive with limited functionality such as joint braces. In spite of recent advances in soft robotics, there is still no soft actuator (motion-generating device) that is portable, i.e. can be operated by on-board power sources, scalable to be adapted to different joint sizes and still have the short response time and high output force-to-size ratio needed to assist joint motions. To address this need, the goal of this project is to design, fabricate and evaluate a novel Electromagnetic Soft Actuator (ESA) that can be easily powered by on-board batteries and can produce linear force and contraction in a manner that mimics the behavior of the contractile filaments (Actin and Myosin) inside a sarcomere (the basic human muscle actuation unit). The ESA is highly scalable and can be miniaturized to create an artificial sarcomere when assembled in parallel and in series. A series of artificial sarcomeres will create an ExoFiber. As the primary activation unit, each artificial sarcomere will be electrically excited separately. The ExoFibers straps will then be embedded into joint braces to make them active. Being activated based on the principle of electromagnetism, the ExoFibers can be quickly energized to generate force and motion. The performance of an ExoFibers-actived brace for the human elbow joint will be evaluated in a small-scale pilot study in humans with and without elbow disabilities. Findings will advance the next generation of flexible, powerful and portable active braces through scalable soft actuators for joint motion assistance and rehabilitation applications and will lay the foundations for interdisciplinary research on the design and analysis of soft actuator networks with dynamic system and materials design and rehabilitation therapy. Education and outreach impact will be achieved through the development of a new graduate level class in Soft Rehabilitation Robotics and working with the UTSA Center for Excellence in Engineering Education (CE3) and iTEC to involve students from underrepresented groups from San Antonio in the project.This exploratory project investigates the possibility of fabricating an Electromagnetic Soft Actuator (ESA) that can be powered by on-board batteries, can produce linear force and contraction in a manner that mimics the behavior of the contractile actin and myosin filaments inside a sarcomere and can be miniaturized to create an artificial sarcomere when assembled in a bioinspired parallel and series pattern. The artificial sarcomeres can be networked into ExoFibers that can be embedded in a human elbow brace that can be used for rehabilitation or as an assistive device. The Research Plan is organized under two aims. AIM 1 is focused on design and fabrication. The ESA design consists of two antagonistic solenoids with a spring linkage in between and an internal ferromagnetic core built with soft materials. By injecting electric current into micro-coils, two antagonistic electromagnetic fields will be induced, resulting in repulsive or attractive forces that stretch or compress the springy linkage. The artificial sarcomere and ExoFibers designs will be assembled using ESAs that have been bioprinted to facilitate ease of production. The number of ESAs assembled in parallel will determine the output source and the number of ESAs in series defines the overall contraction. AIM 2 is focused on development and evaluation of dynamic properties of an active brace, i.e., brace embedded with an ExoFiber. Experimental platforms will be set up to test performance at three levels: single ExoFiber, active brace, and human elbow. The output performance can be defined in terms of: 1) contraction length, output force, linear stiffness and bandwidth for ExoFiber, 2) flexion range, torque, angular stiffness and bandwidth for active brace, and 3) flexion range and comfort and ease of use with a human elbow. The active brace level will be evaluated while the brace is placed on a bioprinted arm model. The human elbow level will be evaluated by conducting a small-scale pilot study in two cohorts of adults: healthy individuals and subjects with elbow weakness, decreased range of motion, or stiffness due to stroke. Participants will be asked to perform three types of exercises: 1) to hold their arm at 5 different flexion-extension stationary angles while suddenly perturb by a 2Nm torque, 2) to flex and extend their arm while holding a 2Kg weight at two different speeds (slow and normal) and 3) to flex their arm while working against a constant torque of 2Nm.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.