Sensory Feedback in Hand Prostheses: A Prospective Study of Everyday Use

Abstract

Introduction Sensory feedback in hand prostheses is lacking but wished for. Many amputees experience a phantom hand map on their residual forearm. When the phantom hand map is touched, it is experienced as touch on the amputated hand. A non-invasive sensory feedback system, applicable to existing hand prostheses, can transfer somatotopical sensory information via phantom hand map. The aim was to evaluate how forearm amputees experienced a non-invasive sensory feedback system used in daily life over a 4-week period. Methods This longitudinal cohort study included seven forearm amputees. A non-invasive sensory feedback system was used over 4 weeks. For analysis, a mixed method was used, including quantitative tests (ACMC, proprioceptive pointing task, questionnaire) and interviews. A directed content analysis with predefined categories sensory feedback from the prosthesis, agency, body ownership, performance in activity , and suggestions for improvements was applied. Results The results from interviews showed that sensory feedback was experienced as a feeling of touch which contributed to an experience of completeness. However, the results from the questionnaire showed that the sense of agency and performance remained unchanged or deteriorated. The ability to feel and manipulate small objects was difficult and a stronger feedback was wished for. Phantom pain was alleviated in four out of five patients. Conclusion This is the first time a non-invasive sensory feedback system for hand prostheses was implemented in the home environment. The qualitative and quantitative results diverged. The sensory feedback was experienced as a feeling of touch which contributed to a feeling of completeness, linked to body ownership. The qualitative result was not verified in the quantitative measurements. Clinical Trial Registration Name: Evaluation of a Non-invasive Sensory Feedback System in Hand Prostheses. Date of registration: March 15, 2019. Date the first participant was enrolled: April 1, 2015. ClinicalTrials.gov Identifier: NCT03876405 ORCID ID: https://orcid.org/0000-0002-4140-7478 .

Wearable Integrated Soft Haptics in a Prosthetic Socket

“…While a 1D force feedback output is sufficient for the purpose of the current work (to deliver force-related information based on an indirect estimation of the overall grasping force of the SoftHand), in the future we will consider other prosthetic hands (including versions of the SoftHand with additional degrees of actuations [26]), where multi-dimensional force feedback could be useful. A possible direction include the use of more chambers, as proposed in [18], controlled by multiple air pumps. Another way could be to combine the air pressure with particle jamming, as explored by Stanley et al (2015), to model the output feedback according to different directions.s…”

“…In [17], the authors present a soft pneumatic actuators able to provide tactile and vibration feedback. In [18], the authors present a passive device based on a glove with silicon bulbs in the fingertips. When they are pressed, the air is transferred via silicone pipes that reached actuators inside the prosthetic socket and gave pressure (mechanotactile feedback) on the skin corresponding with the phantom hand map zones in the residual limb.…”

Can Prosthetic Hands Mimic a Healthy Human Hand?

“…Somatosensory stimuli are integral components of our sensorimotor behaviors such as touch and proprioception. Loss of somatosensory perception limits our ability to control motor function [8]. Due to developments in neural interface technologies and the discoveries of their critical role in improving the functionality of prosthetic limbs for amputees, research into somatosensory neural prostheses has advanced rapidly in recent decades.…”

“…Although commercial myoelectric prostheses can simulate many human gestures with help from microprocessors, they commonly lack sensory feedback. Without sensory feedback, myoelectric prosthesis users do not have the tactile sense they need to control their prostheses [8]. Hence, the control is done by visual feedback.…”

Modulation Ranges of Different Sensations for Coding Electrically Evoked Tactile Sensory Feedback

“…The interface, the implanted location, and current parameters used in invasive techniques could affect the perceptual qualities [9], [10], [15] and multiple sensory modalities [8], [16]- [18]. While studies of peripheral nerve electrical stimulation show the sophisticated sensory function [17], [19], [20] with a relatively long time [11], [12], [21], non-invasive sensory feedback studies are still relatively limited in the use of sensation qualities [22], [23].…”