Abstract:
Commercially used prostheses are essentially open-loop devices and provide little or no feedback
to the amputee as to how much force they exerting with the terminal device, despite numerous
attempts to provide closed loop control in prosthetics [1]. Providing pressure feedback clearly
has great value for function of the prosthesis—the goal is for the amputee to ‘feel’ what they are
holding. Indirect pressure feedback has been attempted by methods including vibration [2] and
functional electrical stimulation [3, 4]. The information contained in these forms of feedback is
not in the same modality as that which they sense. As a result, while providing information to the
user, it is likely that it comes at the cost of increased mental load and low level of information
transfer [5]. Patterson and Katz [6] have obtained better qualitative feedback with pressure to
pressure feedback than with pressure to vibratory or electrical stimulation feedback, offering
support for this suggestion. An adaptive process is still involved since the subject must learn to
associate pressure in one area with pressure in another area. Ideally, the sensory nerve endings of
the amputated area need to be stimulated in direct correlation to the function of the prosthesis.
The recent work of Kuiken [7] has made this concept feasible by the use of targeted
reinnervation. The potential thus exists for the subject to feel as if touch, pressure and even hot
or cold temperatures are being exerted on their hand. This study will examine the potential of
intuitive pressure feedback.
