Effect of fiber annealing temperature on twisted and coiled UHMWPE actuator performance

Twisted and coiled polymer (TCP) actuators are flexible, wearable, and cost effective. However, the effects of annealing temperature on the properties of these devices are poorly understood. Thus, TCPs were prepared using ultra-high molecular weight polyethylene (UHMWPE) fibers and NiCr string and characterized. High-temperature annealing caused internal crystal-phase transformation, and annealing at 130 degrees C yielded a coiled fiber with optimized mechanical properties. Electromechanical tests confirmed that TCPs prepared from UHMWPE fibers annealed at 130 degrees C exhibited the best performance. Additionally, the voltage, displacement, tensile force, and temperature variation in the TCP fibers were recorded under different driving currents and pre-load forces to determine the optimal working conditions, and 1200-cycle life-span tests were carried out for validation. Finally, the driving performance of a TCP array was explored, and the range of motion, pressure, and possibility of lifting weights were tested using a model finger. Overall, the TCP array can be used as a soft actuated dexterous hand robot.