A novel gel liner system with embedded electrodes for use with upper limb myoelectric prostheses
June
A novel gel liner system with embedded electrodes for use with upper limb myoelectric prostheses
Timothy Reissman 0 1 2 3
Elizabeth Halsne 0 2 3
Robert Lipschutz 0 2 3
Laura Miller 0 2 3
Todd Kuiken 0 1 2 3
0 Current address: Department of Mechanical Engineering, University of Dayton , Dayton, OH , United States of America
1 Department of Biomedical Engineering, Northwestern University , Chicago, IL , United States of America
2 Center for Bionic Medicine, Rehabilitation Institute of Chicago , Chicago, IL , United States of America
3 Editor: Yih-Kuen Jan, University of Illinois at Urbana-Champaign , UNITED STATES
We present the development and evaluation of a gel liner system for upper limb prosthesis users that enables acquisition of electromyographic (myoelectric) control signals through embedded electrodes and flexible, conductive fabric leads. This liner system is constructed using a manufacturing approach rather than by modifying a commercially available liner. To evaluate the efficacy, eight male individuals with transhumeral amputations used this system, with standard myoelectric prostheses, for home trials lasting an average of 7.3 weeks. Before and after the home trials, electrical resistance of the cumulative 218 embedded electrodes and leads within 10 gel liner systems was measured and found to increase slightly (from an average of 13.4 to 27.5 Ω) after usage. While this increase was statistically significant (p = 0.001), all but one of the final resistance values remained low enough to enable consistent myoelectric control. User impressions were evaluated through a questionnaire comparing the liner prototypes to their own myoelectric prosthesis socket interface. Subjects preferred the liner prototype (p = 0.008) over their own system in the clinical areas of comfort, suspension, function, and, especially, ease of use. These results suggest that this gel liner system is a clinically viable option and that it may offer advantages over current clinical technology for users of upper limb myoelectric prostheses.
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Data Availability Statement: All relevant data are
within the paper and its Supporting Information
files.
Funding: Development funding was given through
US Army TATRC W81-XWH-11-1-0720 and
National Institute of Health CDMRP W81XWH
1202-0072 (TK). Funding for the lead author to
conduct the research presented was supported by
NIH T32 HD07418 (TR).
Competing interests: The authors declare the
issuance of two patents related to the technology
Introduction
For nearly three decades, individuals with amputations have used roll-on elastomeric gel
liners, made from a variety of materials, as an interface between their residual limb and a rigid
outer socket [1±3]. Such liner systems are reported to offer benefits, including cushioning of
soft tissue and bony prominences, protection of the skin from friction caused by relative
motion between the limb and socket, improved suspension via locking mechanisms or suction
sealing, and increased adjustability of fit [
3
]. Although liners have historically been used for
individuals with lower limb amputations, they have also been increasingly adopted for upper
limb prosthetic fittings due to their comfort, ease of donning/doffing, and optimal device
suspension [
4, 5
].
For individuals who use myoelectric, externally powered upper limb prostheses, which are
controlled by skin-surface electromyographic (EMG) signals, the socket must fit the residual
limb tightly to prevent loss of contact between the electrodesÐtypically mounted in the socket
wallÐand the skin covering the residual limb muscles. This tight fit often necessitates the use
of a donning aid to pull the residual limb tissues into the socket, which has the tendency to
make the donning process time-consuming, physically demanding, and prone to error or
discomfort. In order to address these challenges, numerous attempts have been made to extend
the benefits of a gel liner interface to upper limb myoelectric prosthesis users [6±10].
The fundamental obstacle to using liner systems with myoelectric devices is that the liner
prevents the necessary contact between the user's skin and the socket-mounted electrodes.
Attempts to overcome this issue have generally involved modifying existing liners to allow
access of electrodes to the skin, either by piercing the liner with metal electrode domes [
2, 7, 8
]
or cutting holes in the liner to expose the skin [
6
]. While both approaches are functional, they
frequently result in damage to the integrity of the liner, reducing its lifespan. Cutting holes in
liners to allow skin contact requires users to don the liner in the correct position (i.e., so that
the holes line up with the electrodes in the socket) to enable EMG signal transmission.
Conversely, while placing domes in the liner removes this requirement, the user must then attach
individual wires to each electrode after donning the liner, which is cumbersome and requires
the user to man (...truncated)