Wet shape memory alloy actuated robotic heart with thermofluidic feedback

This paper presents the design, optimization, and experimental analysis of a biologically inspired wet shape memory alloy (SMA) actuated heart for robotic systems. Just as the human heart provides energy to the muscles in the body, the robotic SMA heart distributes thermofluidic energy to arrays of SMA actuators that function as robotic muscles. Furthermore, the robotic heart draws from its own fluidic output to assist in the actuation of its own internal SMA actuators, just as a portion of the blood pumped by the human heart supplies energy to its own muscles. Dynamic modeling and simulation of the SMA actuators and pumping system are used to assist in optimizing the output of the heart. The effects of changing various parameters such as actuator length and actuation timing were explored via simulation and experiment. The current prototype of the SMA heart is capable of pumping 2.1 times more fluid than is required to sustain its own actuation. This is the first successful implementation of such a robotic heart, such that it has a net positive thermofluidic output to provide to other actuators while sustaining its own actuation via thermofluidic feedback. Furthermore, the SMA heart is capable of pumping a net output of 66 mL/min, which is two orders of magnitude larger than the output of other SMA “micro” pumps.