On the viability of implantable electrodes for the natural control of artificial limbs: review and discussion.

Max Ortiz-Catalan,Rickard Brånemark,Bo Håkansson,Jean Delbeke

doi:10.1186/1475-925x-11-33

Abstract

The control of robotic prostheses based on pattern recognition algorithms is a widely studied subject that has shown promising results in acute experiments. The long-term implementation of this technology, however, has not yet been achieved due to practical issues that can be mainly attributed to the use of surface electrodes and their highly environmental dependency. This paper describes several implantable electrodes and discusses them as a solution for the natural control of artificial limbs. In this context “natural” is defined as producing control over limb movement analogous to that of an intact physiological system. This includes coordinated and simultaneous movements of different degrees of freedom. It also implies that the input signals must come from nerves or muscles that were originally meant to produce the intended movement and that feedback is perceived as originating in the missing limb without requiring burdensome levels of concentration. After scrutinizing different electrode designs and their clinical implementation, we concluded that the epimysial and cuff electrodes are currently promising candidates to achieving a long-term stable and natural control of robotic prosthetics, provided that communication from the electrodes to the outside of the body is guaranteed.

Highlights

Myoelectric prostheses were devised in the late 1940s [1] and have been clinically implemented since the 1960s [2], they are still a long way from the functionality of their biological counterpart
We have focused on biopotential electrodes being placed in the peripheral nervous system, some of them can be used in the central nervous system as so-called brain computer interfaces (BCI)
We have presented evidence suggesting that both muscle- and nerve-based implantable electrodes, if properly located and implanted, are a viable solution for the long-term implementation of natural prosthetic control

Summary

Introduction

Myoelectric prostheses were devised in the late 1940s [1] and have been clinically implemented since the 1960s [2], they are still a long way from the functionality of their biological counterpart. Prosthetic hardware is considerably more advanced than the control strategies needed to command it Sophisticated prostheses such as the SmartHand [3] provide more degrees of freedom than a patient is able to control naturally. Sensors embedded in the prosthesis can provide valuable feedback information that currently has no stable means of being naturally transmitted to the patient [4]. In this context, “natural” is defined as producing control in the same way as an intact physiological system. “natural” is defined as producing control in the same way as an intact physiological system This means coordinated and simultaneous movements of different degrees of freedom. Natural control is a fundamental feature that is greatly appreciated by patients [5]

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Conclusion