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Online Closed-Loop Control Using Tactile Feedback Delivered Through Surface and Subdermal Electrotactile Stimulation

Research output: Contribution to journalArticlepeer-review

Jian Dong, Winnie Jensen, Bo Geng, Ernest Kamavuako, Strahinja Dosen

Original languageEnglish
Article number580385
JournalFrontiers in Neuroscience
Volume15
DOIs
Published18 Feb 2021

Bibliographical note

Funding Information: Funding. This work was supported by the Danish Council for Independent Research under Grant 1337-00130, and Grant 8022-00243A (ROBIN), and SC Van Fonden No. 1675. Publisher Copyright: © Copyright © 2021 Dong, Jensen, Geng, Kamavuako and Dosen. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.

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    2021_Dong_et_al.pdf, 1.02 MB, application/pdf

    Uploaded date:19 Feb 2021

    Version:Final published version

King's Authors

Abstract

Aim: Limb loss is a dramatic event with a devastating impact on a person’s quality of life. Prostheses have been used to restore lost motor abilities and cosmetic appearance. Closing the loop between the prosthesis and the amputee by providing somatosensory feedback to the user might improve the performance, confidence of the amputee, and embodiment of the prosthesis. Recently, a minimally invasive method, in which the electrodes are placed subdermally, was presented and psychometrically evaluated. The present study aimed to assess the quality of online control with subdermal stimulation and compare it to that achieved using surface stimulation (common benchmark) as well as to investigate the impact of training on the two modalities. Methods: Ten able-bodied subjects performed a PC-based compensatory tracking task. The subjects employed a joystick to track a predefined pseudorandom trajectory using feedback on the momentary tracking error, which was conveyed via surface and subdermal electrotactile stimulation. The tracking performance was evaluated using the correlation coefficient (CORR), root mean square error (RMSE), and time delay between reference and generated trajectories. Results: Both stimulation modalities resulted in good closed-loop control, and surface stimulation outperformed the subdermal approach. There was significant difference in CORR (86 vs 77%) and RMSE (0.23 vs 0.31) between surface and subdermal stimulation (all p < 0.05). The RMSE of the subdermal stimulation decreased significantly in the first few trials. Conclusion: Subdermal stimulation is a viable method to provide tactile feedback. The quality of online control is, however, somewhat worse compared to that achieved using surface stimulation. Nevertheless, due to minimal invasiveness, compactness, and power efficiency, the subdermal interface could be an attractive solution for the functional application in sensate prostheses.

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