A non-invasive wearable sensory leg neuroprosthesis: mechanical, electrical and functional validation

Abstract

Objective. Lower limb amputees suffer from a variety of functional deficits related to the absence of sensory communication between the central nervous system and the lost extremity. Indeed, they experience high risk of falls, asymmetric walking and balance, and low prosthesis embodiment, that significantly decrease their quality of life. Presently, there are no commercially available devices able to provide sensory feedback to leg amputees. Recently, some invasive solutions (i.e. requiring a surgery) have been proposed by different research groups, however a non-invasive effective alternative exploitable in everyday life is still missing. Approach. To address this need we developed and tested a lightweight, non-invasive, wearable technology (NeuroLegs) providing sensory (i.e. knee angle joint and tactile) feedback to the users through electro-cutaneous stimulation. A user-friendly GUI and mobile App have been developed to easily calibrate and control the system. Standard mechanical and electrical tests were performed to assess the safety and reliability of the technology. Main results. No mechanical failures, stable communication among system parts and a long-lasting battery (>23h) were demonstrated. The NeuroLegs system was then verified in terms of accuracy in measuring relevant gait parameters in healthy participants. A high temporal reliability was found when detecting stride features (important for the real-time configuration) with a correct match to the walking cadence, in all assessed walking conditions. The effectiveness of the NeuroLegs system at improving walking of three transfemoral amputees was then verified in movement laboratory tests. Increased temporal gait symmetry and augmented confidence were found. Stepping outside from the lab, Neurolegs was successfully exploited by a transfemoral amputee in CYBATHLON Global Edition 2020 in several challenging situations related to daily-living activities. Significance. Our results demonstrate that the NeuroLegs system provides the user with useful sensory information that can be successfully exploited in different walking conditions of daily life.

Multisensory stimulation decreases phantom limb distortions and is optimally integrated

“…Finally, the effect of training in the likelihood of optimal integration of artificial sensory signals would be an interesting topic for future research. Indeed, the participants reported in this study have already exploited the remapped artificial stimulation in combination with a prosthetic device ( Basla et al., 2021 ). This previous experience might influence the sensory integration process.…”

“…The subjects had undergone a traumatic amputation because of accidents in 2018, 2013, and 2007. All the three subjects already exploited a remapped sensory feedback system on their prostheses in some motor tasks ( Basla et al., 2021 ). Because the amount of time necessary for the experiments did not comply with his job, Subject 3 preferred not to participate in experiment 1.…”

Integrated Memristor Network for Physiological Signal Processing

“…The most successfully researched neuroprosthetics are for patients with impaired sensory organs, such as cochlear implants and wearable leg neuroprosthetics. [188,189] In addition to the previous research, current studies are trying to develop visual prostheses to help blind people see the world again. Neural spike detection is very important in developing neuroprosthetics for treating neurological disorders, focusing on detecting the timing of the spike delivery of individual neurons.…”

“…b) Wearable leg neuroprosthetics. Reproduced under the terms of the CC-BY license [188]. Copyright 2022, IOP Publishing.…”

Reshaping the full body illusion through visuo-electro-tactile sensations

“…However, its integration with various technologies, necessary for virtual embodiment, can be daunting [ 23 ]. In particular, somatosensory feedback should be carefully chosen based on several important characteristics [ 24 ]. First of all, given that our skin has numerous and specialized touch receptor cells, the haptic technology should be decided based on the target application and take into account the safety of the participant [ 23 ].…”