MyoFit: A new approach to suspension for upper limb myoelectric prostheses



 DESCRIPTION (provided by applicant): A new approach to suspension for upper limb myoelectric prostheses. The overall goal of our research program is to empower upper limb amputees to be productive and independent. For these individuals, one of the most promising developments in the past decade has been the introduction of fully dexterous terminal devices. However, an effective and intuitive control strategy has remained elusive. Myoelectric control (typically utilizing two surface EMG electrodes) works well for one or two degree-of-freedom devices, but it is not as effective when dealing with a large number of movement classes (such as when attempting to discriminate amongst "hand open", "index finger point", "fine pinch", and so on). Thus significant research has been undertaken on decoding the amputee's intention using signals from a larger number of surface EMG electrodes - typically eight pairs. However, optimal performance is dependent on high- quality surface EMG signal acquisition. Small changes in electrode position or in contact between the electrode and the skin results in significant degradation in system performance. One primary reason is that the design of the standard anatomically suspended prosthesis did not anticipate the evolution of prosthesis technology to include this need for highly stable multichannel surface EMG signal acquisition. Thus there is a need to fundamentally rethink prosthesis design in light of the new opportunity to achieve dexterous control. Specifically, in this Fast Track effort we propose development of the MyoFit system to replace the standard anatomical suspended prosthesis. It includes a roll-on silicone gel liner which is fabricated to incorporate eight flexible surface EMG electrodes. The liner (and by extension the electrodes) interfaces with the socket and frame of the prosthesis via a two-part pin-lock system. The system enables a stable electrode-skin interface, including when the prosthesis is bearing load and when it is being moved to various positions in the workspace. During Phase I we will develop and complete engineering validation of the liner and the lock. In Phase II, we will complete system integration and FDA regulatory clearance. We will also undertake a clinical study to evaluate the functional benefits of the MyoFit system as compared to the standard anatomically suspended prosthesis. It is our ultimate goal for the MyoFit system to enable upper limb amputees to achieve a superior clinical functional outcome.