RELab tenoexo: a Robotic Hand Orthosis for Therapy and Assistance in Activities of Daily Living

Stroke, spinal cord injury, and cerebral palsy are just a few examples of diseases leading to persistent hand impairment. No matter the cause, the inability to use the affected hand in activities of daily living will affect independence and quality of life. Wearable robotic devices can support the use of the impaired limb in activities of daily living and provide at-home rehabilitation training.

Our robotic hand orthosis, the RELab tenoexo, aims to assist people in grasping tasks during task-oriented therapy and in activities of daily living, such as eating or grooming, by supporting various grasp types. The device underwent various iterative design and evaluation cycles to improve its functionality and usability. The current prototypes, the RELab tenoexo (Bützer et al. 2020) and PEXO (Bützer et al., 2019), are fully wearable and consist of a lightweight hand module (<150 g) as well as a back module including motors, power source, and controllers (720 g), which can be worn as a backpack or mounted on the backrest of a wheelchair. The RELab tenoexo's remote actuation system (Dittli et al., 2020; Hofmann et al., 2018) and its compliant 3-layered sliding spring mechanism (Arata et al., 2013) ensure safe operation and inherent adaptation to the shape of the grasped objects. The actuated thumb module allows for both opposition and lateral grasps. The hand module is fabricated to a large extent by 3D-printing technology and laser cutting. With an underlying automatic tailoring algorithm, a range of possible intention detection strategies and a selection of physical attachment systems, it can be adapted to the individual user’s needs and preferences. The maximal fingertip force of 5 N per finger allows for grasping and lifting of most everyday objects, up to 0.5-liter water bottles.

The RELab tenoexo and PEXO have proved to generate an immediate functional benefit in adults after a spinal cord injury (Dittli et al., 2023) and children with severe hand impairment (Lieber et al., 2022). In collaboration with our clinical partners from the Balgrist University Hospital, the Swiss Children’s Rehab of University Hospital Zurich, and the EOC Neurocentro in Lugano, our current focus is on further evaluating tenoexo and PEXO with several individuals and exploring its potential as an assistive and therapeutic device. Specifically, we want to investigate how tailoring the device to the individual users affects its functionality and usability and whether the robotic hand orthoses can be used in different settings in the home environment.