Assessing Heat-Driven 4D Printed Finger Actuators with Conductive Wires: A Parametric Analysis

4D printing, utilizing the fourth dimension of time, allows for the creation of time-dependent objects that can morph and adapt. This capability has shown great potential in soft robotics, particularly in developing soft actuators for adaptive movement. Heat-sensitive shape-memory polymers are a key component in this process, enabling programmed shape changes in response to temperature change. In this study, the heat induced wire is used as the heat stimulus for the 4D printed self-actuator finger. The objectives are to observe the effect of current, temperature, and wire arrangement to the deflection of self-actuator finger, and to obtain the optimum parameters for actuation. The deflection angle and the deflection radius are measured in this study to evaluate the finger performance aiming for a larger deflection angle and a smaller curvature radius. In addition, the effect of the fin on the deflection is also observed. An ANOVA method was used to statistically determine the significant effects of the current, temperature and wire arrangement and to obtain the optimum parameters. Result shows that current, temperature, and wire arrangement all have significant impacts on deflection. The 5.2 Ampere current offers better deflection results compared to 4 Ampere or lower. When the temperature exceeds the PLA's glass transition temperature in the wire, the specimen deflects according to the programmed direction. Additionally, utilizing 3 nitinol wires resulted in greater deflection than using 2. The optimal parameters for maximum deflection are 3 power supplies, 3 nitinol wire, and 5.2 amperes. Furthermore, a design with fins achieves better deflection compared to a design without fins.