2022 journal article

Freeform printing and modeling of soft twisting electrothermal actuators

Manufacturing Letters, 33, 41–47.

By: Y. Cao* & J. Dong n

Contributors: J. Dong n

Source: ORCID
Added: September 21, 2022

Soft electrothermal actuators have drawn extensive attention in recent years for their promising applications in biomimetic and biomedical areas. Most soft electrothermal actuators reported so far demonstrated uniform bending deformation, due to the deposition-based fabrication of the conductive heater layer from nanomaterial-based solutions, resulting in uniform heating and bending. Twisting represents another degree-of-freedom for soft actuators to enhance their versatility and functionality. In this paper, a soft electrothermal actuator that can provide twisting deformation was designed and fabricated. The two structural layers of the actuator are made of polyimide (PI) and polydimethylsiloxane (PDMS), which are selected due to their distinct thermal expansion properties. Embedded in between the two structural layers is a metallic microfilament heater layer that is directly printed using electrohydrodynamic (EHD) printing. Assisted by the freeform direct patterning capabilities of EHD printing, a skewed heater pattern was designed and printed. This skewed heater pattern not only produces a skewed parallelogram-shaped temperature field, but also changes the stiffness anisotropy of the actuator, leading to twisting deformation with coupled bending. The fabricated twisting actuator was characterized on its heating and twisting performance at different supply voltages. Finite element analysis (FEA) was utilized for the thermal and deformation analysis of the actuator. Using three twisting actuators, a soft gripper was designed and fabricated to implement pick-and-place operations of delicate objects.