MyoFit: 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 independentFor these individualsone of the most promising developments in the past decade has been the introduction of fully dexterous terminal devicesHoweveran effective and intuitive control strategy has remained elusiveMyoelectric controltypically utilizing two surface EMG electrodesworks well for one or two degree of freedom devicesbut it is not as effective when dealing with a large number of movement classessuch as when attempting to discriminate amongsthand openindex finger pointfine pinchand so onThus significant research has been undertaken on decoding the amputee s intention using signals from a larger number of surface EMG electrodestypically eight pairsHoweveroptimal performance is dependent on highquality surface EMG signal acquisitionSmall changes in electrode position or in contact between the electrode and the skin results in significant degradation in system performanceOne 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 acquisitionThus there is a need to fundamentally rethink prosthesis design in light of the new opportunity to achieve dexterous controlSpecificallyin this Fast Track effort we propose development of the MyoFit system to replace the standard anatomical suspended prosthesisIt includes a roll on silicone gel liner which is fabricated to incorporate eight flexible surface EMG electrodesThe linerand by extension the electrodesinterfaces with the socket and frame of the prosthesis via a two part pin lock systemThe system enables a stable electrode skin interfaceincluding when the prosthesis is bearing load and when it is being moved to various positions in the workspaceDuring Phase I we will develop and complete engineering validation of the liner and the lockIn Phase IIwe will complete system integration and FDA regulatory clearanceWe will also undertake a clinical study to evaluate the functional benefits of the MyoFit system as compared to the standard anatomically suspended prosthesisIt is our ultimate goal for the MyoFit system to enable upper limb amputees to achieve a superior clinical functional outcome