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

神经功能受损的人，如中风患者，经常需要帮助移动关节。然而，目前的可穿戴康复和辅助设备要么是1）强大和主动的，但体积庞大，并由刚性元件制成，如外骨骼和假肢，要么是2）柔性但被动的，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致动器（运动产生装置），即，可以由机载电源操作，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-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），可以很容易地由板载电池供电，并可以产生线性力和收缩的方式，模仿收缩丝（肌动蛋白和肌球蛋白）内肌节（基本的人体肌肉驱动单元）的行为。 ESA是高度可扩展的，并且可以被小型化以在并行和串联组装时创建人造肌节。一系列的人造肌节将创造一个ExoFiber。作为主要的激活单元，每个人工肌节将被单独地电激励。然后将ExoFibers绑带嵌入关节支架中，使其处于活动状态。 基于电磁原理激活，ExoFibers可以快速通电以产生力和运动。 ExoFibers激活支具用于人类肘关节的性能将在有和没有肘关节残疾的人类中进行的小规模试点研究中进行评价。研究结果将通过可扩展的软致动器推进下一代灵活，强大和便携式主动支架，用于关节运动辅助和康复应用，并将为软致动器网络的设计和分析与动态系统和材料设计和康复治疗的跨学科研究奠定基础。 通过开发一个新的软康复机器人研究生课程，并与UTSA工程教育卓越中心（CE 3）和iTEC合作，让来自圣安东尼奥代表性不足的群体的学生参与该项目，将实现教育和推广影响。该探索性项目研究制造电磁软致动器（ESA）的可能性，该致动器可以由车载电池供电，可以以模仿肌节内收缩性肌动蛋白和肌球蛋白细丝的行为的方式产生线性力和收缩，并且当以生物启发的平行和串联模式组装时可以被小型化以产生人造肌节。 人造肌节可以联网到ExoFibers中，ExoFibers可以嵌入人体肘部支架中，可用于康复或作为辅助设备。 研究计划是根据两个目标组织的。 AIM 1专注于设计和制造。 ESA的设计包括两个对抗性的磁铁，中间有一个弹簧连接，内部有一个软材料制成的铁磁芯。通过将电流注入微线圈，将感应出两个对抗的电磁场，从而产生排斥力或吸引力，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组装，以便于生产。 并行组装的ESA的数量将决定输出源，而串联的ESA的数量定义了总体收缩。 AIM 2的重点是开发和评估主动支具的动态特性，即，嵌入ExoFiber的支架。 将建立实验平台来测试三个级别的性能：单个ExoFiber、主动支架和人体肘部。输出性能可以根据以下方面来定义：1）ExoFiber的收缩长度、输出力、线性刚度和带宽，2）主动支具的屈曲范围、扭矩、角刚度和带宽，以及3）屈曲范围和舒适度以及与人类肘部一起使用的易用性。 当支架放置在生物打印手臂模型上时，将评估活动支架水平。 将通过在两个成人队列中进行小规模初步研究来评价人体肘部水平：健康个体和肘部无力、活动范围减少或中风所致僵硬的受试者。参加者将被要求进行三种类型的练习：1）在突然受到2Nm扭矩的扰动时，将他们的手臂保持在5个不同的屈曲-伸展静止角度，2）以两种不同的速度弯曲和伸展手臂，同时保持2Kg的重量（缓慢和正常）和（3）该奖项反映了NSF的法定使命，并通过使用基金会的知识产权进行评估，被认为值得支持。优点和更广泛的影响审查标准。

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.