Laboratory for Biomimetic Membranes and Textiles, Empa, Swiss Federal Laboratories for Materials Science and Technology, Lerchenfeldstrasse 5, 9014, St. Gallen, Switzerland.
Sensory-Motor Systems Lab, Department of Health Sciences and Technology, Institute of Robotics and Intelligent Systems, ETH Zurich, Tannenstrasse 1, TAN E 5, 8092, Zurich, Switzerland.
J Neuroeng Rehabil. 2020 Apr 9;17(1):47. doi: 10.1186/s12984-020-00673-7.
Tremor is the most common movement disorder with the highest prevalence in the upper limbs. The mechanical suppression of involuntary movements is an alternative and additional treatment to medication or surgery. Here we present a new, soft, lightweight, task asjustable and passive orthosis for tremor suppression.
A new concept of a manual, textile-based, passive orthosis was designed with an integrated, task adjustable, air-filled structure, which can easily be inflated or deflated on-demand for a certain daily activity. The air-filled structure is placed on the dorsal side of the wrist and gets bent and compressed by movements when inflated. In a constant volume air-filled structure, air pressure increases while it is inflating, creating a counterforce to the compression caused by bending. We characterised the air-filled structure stiffness by measuring the reaction torque as a function of the angle of deflection on a test bench. Furthermore, we evaluated the efficacy of the developed passive soft orthosis by analysing the suppression of involuntary movements in the wrist of a tremor-affected patient during different activities of daily living (i.e. by calculating the power spectral densities of acceleration).
By putting special emphasis on the comfort and wearability of the orthosis, we achieved a lightweight design (33 g). The measurements of the angular deflection and resulting reaction torques show non-linear, hysteretic, behaviour, as well as linear behaviour with a coefficient of determination (R) between 0.95 and 0.99. Furthermore, we demonstrated that the soft orthosis significantly reduces tremor power for daily living activities, such as drinking from a cup, pouring water and drawing a spiral, by 74 to 82% (p = 0.03); confirmed by subjective tremor-reducing perception by the patient.
The orthosis we developed is a lightweight and unobtrusive assistive technology, which suppresses involuntary movements and shows high wearability properties, with the potential to be comfortable. This air-structure technology could also be applied to other movement disorders, like spasticity, or even be integrated into future exoskeletons and exosuits for the implementation of variable stiffness in the systems.
震颤是最常见的运动障碍，以上肢最为常见。机械抑制不自主运动是一种替代药物或手术的治疗方法。在这里，我们提出了一种新的、柔软的、轻便的、任务自适应的被动矫形器，用于抑制震颤。
我们设计了一种新的手动、基于纺织品的、被动矫形器的概念，它具有集成的、任务自适应的充气结构，可以根据特定的日常活动轻松按需充气或放气。充气结构放置在手腕的背侧，当充气时会因运动而弯曲和压缩。在恒体积充气结构中，随着充气的进行，空气压力会增加，从而产生与弯曲压缩相反的反作用力。我们通过在测试台上测量作为挠度函数的反作用扭矩来表征充气结构的刚度。此外，我们通过分析震颤患者在不同日常生活活动（即通过计算加速度的功率谱密度）中手腕的不自主运动抑制情况，评估了所开发的被动软矫形器的疗效。
通过特别强调矫形器的舒适性和可穿戴性，我们实现了轻量级设计（33 克）。角偏转和相应的反作用扭矩的测量结果显示出非线性、滞后行为，以及在 0.95 到 0.99 之间的决定系数（R）的线性行为。此外，我们证明了软矫形器可以显著降低日常生活活动中的震颤功率，如从杯子里喝水、倒水和画螺旋，降低幅度为 74%到 82%（p=0.03）；这一效果得到了患者对震颤减轻的主观感知的证实。
我们开发的矫形器是一种轻便、不显眼的辅助技术，它可以抑制不自主运动，具有很高的可穿戴性，有可能舒适。这种空气结构技术也可以应用于其他运动障碍，如痉挛，甚至可以集成到未来的外骨骼和外骨骼中，为系统实现可变刚度。
