Patterned Aluminum/Polydimethylsiloxane-Laminated Film for a Solvent-Driven Soft Actuator with Programmable and Multistable Shape Morphing.

Recently, soft actuators capable of deforming in predictable ways under external stimuli have attracted increasing attention by showing great potential in emerging industries. However, limited efforts are being spent on the untethered actuators with multistable deformations. Also, there is a lack of mechanically guiding design principles for multistable structures. Here, the patterned aluminum/polydimethylsiloxane (Al/PDMS)-laminated films with surface wrinkles are fabricated by magnetron sputtering the Al layer on the PDMS substrate. By tuning the geometric parameters and surface constraints of the patterned Al/PDMS-laminated films, a series of solvent-driven actuators with multiform stable configurations (such as monostable arc, multistable cylinder, and monostable/bistable spiral) are proposed. The deformation mechanism is revealed using a linear elastic theory. Combined with the finite element analysis method, the deformations of Al/PDMS-laminated films with different surface constraints and geometric configurations are visually predicted. Besides, we modulate the deformation of different parts of the Z-shaped actuators by tuning the surface constraints in different regions of the Z-shaped Al/PDMS bilayer films to achieve multiple stable deformations in a single actuator. The concept offers a huge design scope for reconfigurable soft robots. Finally, two bionic applications are proposed to demonstrate the practical applications of the soft solvent-driven actuator based on the patterned Al/PDMS films in artificial muscles and bionic robotics. This work provides a strategy for the design and fabrication of programmable and controllable soft actuators, laying the foundation for a wide range of applications in smart materials.