Bioinspired Design of Vascular Artificial Muscle

Recently, liquid crystal elastomers (LCEs) have drawn much attention for its wide applications as artificial muscle in soft robotics, wearable devices, and biomedical engineering. One commonly adopted way to trigger deformation of LCEs is using embedded heating elements such as resistance heating wires and photothermal particles. To enable the material to recover to its unactuated state, passive and external cooling is often employed to lower the temperature, which is typically slow and environmentally sensitive. The slow and uncontrollable recovery speed of thermally driven artificial muscle often limits its applications when even moderate cyclic actuation rate is required. In this article, inspired by biology, a vascular LCE-based artificial muscle (VLAM) is designed and fabricated with internal fluidic channel in which the hot or cool water is injected to heat up or cool down the material to achieve fast actuation as well as recovery. It is demonstrated that the actuation stress, strain, and cyclic response rate of the VLAM are comparable to mammalian skeletal muscle. Because of the internal heating and cooling mechanism, VLAM shows a very robust actuating performance within a wide range of environmental temperatures. The VLAM designed in this article may also provide a convenient way to harvest waste heat to conduct mechanical work.