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A soft neuroprosthetic hand providing simultaneous myoelectric control and tactile feedback

Abstract

Neuroprosthetic hands are typically heavy (over 400 g) and expensive (more than US$10,000), and lack the compliance and tactile feedback of human hands. Here, we report the design, fabrication and performance of a soft, low-cost and lightweight (292 g) neuroprosthetic hand that provides simultaneous myoelectric control and tactile feedback. The neuroprosthesis has six active degrees of freedom under pneumatic actuation, can be controlled through the input from four electromyography sensors that measure surface signals from residual forearm muscles, and integrates five elastomeric capacitive sensors on the fingertips to measure touch pressure so as to enable tactile feedback by eliciting electrical stimulation on the skin of the residual limb. In a set of standardized tests performed by two individuals with transradial amputations, we show that the soft neuroprosthetic hand outperforms a conventional rigid neuroprosthetic hand in speed and dexterity. We also show that one individual with a transradial amputation wearing the soft neuroprosthetic hand can regain primitive touch sensation and real-time closed-loop control.

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Fig. 1: Design and operation of the soft neuroprosthetic hand.
Fig. 2: Performance characterization of the soft neuroprosthetic hand.
Fig. 3: An individual with a transradial amputation wearing the soft neuroprosthetic hand, restoring the versatile hand functions in daily activities.
Fig. 4: An individual with a transradial amputation wearing the soft neuroprosthetic hand, restoring the primitive touch sensation and the closed-loop control in blindfolded and acoustically shielded interaction experiments.

Data availability

The main data supporting the results in this study are available within the paper and its Supplementary Information. Source data for Fig. 3a and Supplementary Figs. 23 and 26 are available as Supplementary Information. All data needed to evaluate the conclusions are presented in the paper and the Supplementary Information.

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Acknowledgements

We thank the participants for agreeing to participate in this research; M. Feng, Z. Shen, X. Huang and N. Ding for their participation in building the experimental set-ups; and Q. He for the discussions of the model and simulation. This study was supported in part by the National Natural Science Foundation of China (grant nos 91948302, 52025057 and 51620105002), the Science and Technology Commission of Shanghai Municipality (grant no. 20550712100), Shanghai Jiao Tong University Scientific and Technological Innovation Funds, and Massachusetts Institute of Technology.

Author information

Authors and Affiliations

Authors

Contributions

G.G., N.Z., X. Zhu and X. Zhao conceived the idea and designed the study. G.G., N.Z., H.X., H.Y., Q.S. and X. Zhu performed experiments and analysed the experimental data. Y.Y., G.C., X.S. and X. Zhu developed the EMG sensors and electrical stimulation platform. G.G., S.L., L.G. and X. Zhao developed the theoretical model and performed the FEM simulation for verification. G.G., X. Zhu and X. Zhao directed the project. G.G., N.Z., H.X., X. Zhu and X. Zhao prepared the manuscript and all of the authors provided feedback and agree with the final version of the manuscript.

Corresponding authors

Correspondence to Guoying Gu, Xiangyang Zhu or Xuanhe Zhao.

Ethics declarations

Competing interests

G.G., N.Z., H.X., S.L., X. Zhu and X. Zhao are listed as co-inventors on a patent application (US application no. 63/039,929) that covers the design and fabrication of the soft neuroprosthetic hand.

Additional information

Peer review information Nature Biomedical Engineering thanks the anonymous reviewers for their contribution to the peer review of this work.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Supplementary methods, figures, tables and references, and captions for Supplementary Videos 1–14.

Reporting Summary

Supplementary Video 1

Simulation and experiments of the individual motion of five soft fingers.

Supplementary Video 2

Demonstration of independent control of 6 d.f. with one pump.

Supplementary Video 3

Demonstration of the durability of a soft finger.

Supplementary Video 4

Demonstration of fast wearing and training of a soft neuroprosthetic hand.

Supplementary Video 5

Evaluation of the soft neuroprosthetic hand with standardized tests.

Supplementary Video 6

Results of the standardized tests by the same participant wearing a rigid neuroprosthetic hand.

Supplementary Video 7

Demonstration of the compliant advantage of the soft neuroprosthetic hand.

Supplementary Video 8

Demonstration of the four electromyography-controlled grasp types.

Supplementary Video 9

Demonstration of versatile hand functions in daily activities of the individual.

Supplementary Video 10

Demonstration of handling objects with different shapes and sizes.

Supplementary Video 11

Demonstration of holding heavy payloads.

Supplementary Video 12

Demonstration of the touch sensation of an individual finger and multiple fingers.

Supplementary Video 13

Demonstration of closed-loop control.

Supplementary Video 14

Demonstration of graded tactile feedback.

Supplementary Dataset 1

Source data for Fig. 3a.

Supplementary Dataset 2

Source data for Supplementary Fig. 23.

Supplementary Dataset 3

Source data for Supplementary Fig. 26.

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Gu, G., Zhang, N., Xu, H. et al. A soft neuroprosthetic hand providing simultaneous myoelectric control and tactile feedback. Nat Biomed Eng (2021). https://doi.org/10.1038/s41551-021-00767-0

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