Ras Labs’ Synthetic Muscle technology promises to resolve major issues facing amputees, most notably the pain of prosthetic slippage and tissue breakdown. Synthetic Muscle, comprising electroactive polymers (EAPs), actively expand or contract at low voltages, while offering impact resistance and pressure sensing, in one integrated solution. In collaboration with United Prosthetics (UPI), customer testing was initiated with these EAP based pads located in strategic areas of the prosthetic socket of both below knee (BK) and above knee (AK) amputees for evaluation and feedback, with very promising results. The goal is to give amputees natural locomotion with a worry-free prosthesis, maintaining dynamic perfect fit throughout the day and preventing tissue damage from even beginning to occur. Robotic gripper applications, with sensing fingertips, were also prototyped. Characterization of Synthetic Muscle as dual use pressure sensors was investigated, with variable voltage observed and quantified when the EAP sensor was mechanically compressed. The integration of EAP shape-morphing actuation into grippers was also initiated. The EAP shape-morphing control is expected to be modulated as needed by controlling the voltage level. This technology is expected to provide for an adjustable prosthetic liner or socket that can maintain dynamic perfect fit and for biomimetic prosthetic hands and robotic grippers.
Lenore Rasmussen, Simone Rodriguez, Matthew Bowers, Gabrielle Franzini, Charles Gentile, George Ascione, Robert Hitchner, James Taylor, Dan Hoffman, Leon Moy, Patrick Mark, Daniel Prillaman, Robert Nodarse, Michael Menegus, Ryan Carpenter, Darold Martin, Matthew Maltese, Thomas Seacrist, Cosme Furlong, Payam Razavi, Greig Martino
Ras Labs Synthetic MuscleTM – a class of electroactive polymers (EAPs) that contract and expand at low voltages – mimic the unique gentle-yet-strong nature of human tissue. These EAPs also attenuate force and sense mechanical pressure, from gentle touch to high impact. This is a potential asset to prosthetics and robotics, including manned space travel through protective gear and human assist robotics and for unmanned space exploration through deep space. Fifth generation Synthetic MuscleTM is very robust and attenuates impact force through non-Newtonian mechanisms. Various electrolyte solutions and conductive additives were also explored to optimize these EAPs. In prosthetics, the interface between the residual limb and the hard socket of the prosthetic device is a pain point. EAP pads that gently contract and expand within the prosthetic socket using 1.5 V batteries will allow for extremely comfortable, adjustable, perfect fit throughout the day for amputees. For robot grippers, EAP linkages can be actuated and EAP sensors placed at the fingertips of the grippers for tactile feedback. Onset of actuation of these EAPs at the nano-level was determined to be within 48 milliseconds, with macro-scale actuation visible to the naked eye within seconds. Smart EAP based materials and actuators promise to transform prostheses and robots, allowing for the treatment, reduction, and prevention of debilitating injury and fatalities, and to further our exploration by land, sea, air, and space.
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