Design of a lightweight passive orthosis for tremor suppression

Abstract

Background: 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. Methods: 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 airfilled 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 tremoraffected patient during different activities of daily living (i.e. by calculating the power spectral densities of acceleration). Results: 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 2) 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. Conclusion: 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 airstructure 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.

Metal‐Textile Laser Welding for Wearable Sensors Applications

“…This method was developed to link polymers membranes and textiles with themselves or with fibers. [ 25,26 ] The laser energy locally heats the polymers above the melting point leading to the physical interlocking of the materials. So far, this technology has only been used for polymer–polymer bonding requiring the melting of both materials.…”

Soluções alternativas para redução dos tremores patológicos da doença de Parkinson: Uma revisão do estado da arte

“…Zhang et al, 2011D. Zhang et al, , 2011, atuador mecânico (Abbasi & Afsharfard, 2018;Arnold et al, 1993;Dantas de sá et al, 2019;Herrnstadt & Menon, 2016;Pledgie et al, 2000;Rocon et al, 2007;Taheri et al, 2014Taheri et al, , 2015Zahedi et al, 2021;Zamanian & Richer, 2019;Zhou et al, 2017), sistemas amortecidos (Buki et al, 2018;Case et al, 2013;Fromme et al, 2020;Kotovsky & Rosen, 1998;Ture Savadkoohi et al, 2021) e materiais inteligentes (Abbasi & Afsharfard, 2018;Kelley & Kauffman, 2020).…”

Tremor-Suppression Orthoses for the Upper Limb: Current Developments and Future Challenges

“…Viscous beam, which was developed by Kotovsky et al in 1998, was the first passive device designed for tremor suppression purposes (Kotovsky and Rosen, 1998). Task-Adjustable Passive Orthosis (TAPO) is the most recent device in this category (Fromme et al, 2020). Fromme et al designed this orthosis based on an air-filled structure and achieved a very compact and lightweight device (33 g).…”

“…In general, the weight of an orthosis increases proportionally to the number of DoFs to be suppressed. Table 1 shows a large variation in the orthoses weights for tremor suppression, ranging from 33 g [TAPO, passive device, air-filled structure (Fromme et al, 2020)] to 1,600 g [Tremor Suppression Orthosis (TSO), active, DC motor (Herrnstadt et al, 2019)]. The average weight of an orthosis is 456 (±409 g).…”

“…Only two semiactive (Case et al, 2015;Zamanian and Richer, 2019) and one active orthosis (Zhou et al, 2018) were assessed with bench testing. All passive devices found in this review performed the tremor suppression assessment on human subjects (Takanokura et al, 2011;Fromme et al, 2020). The average efficacy of tremor suppression using wearable orthoses is 83 (±13%).…”