Laser‐Induced Graphene for Electrothermally Controlled, Mechanically Guided, 3D Assembly and Human–Soft Actuators Interaction

Abstract

Strategically designed, well-defined 3D architectures could offer great opportunities, that are unavailable in their 2D counterparts, for a broad spectrum of applications, such as microelectronics, bioelectronics, photonics and optoelectronics, micro-electromechanical systems, metamaterials, energy storage and harvesting, soft robotics, and many others. Existing manufacturing techniques of 3D structures mainly include 3D printing, templated growth, fluidic self-assembly, and mechanically guided 3D assembly. Among these methods, the mechanically guided 3D assembly has recently attracted broad attention in the scientific community. The process starts from the planar fabrication of patterned 2D precursor structures, followed by the 2D-to-3D shape transformation via controlled rolling, folding, curving, and/ or buckling. [4] This process is naturally compatible with existing advanced planar fabrication technologies (e.g., lithographic and laser-processing techniques). Consequently, micro/nanoscale structures, sensors and/or other functional components Mechanically guided, 3D assembly has attracted broad interests, owing to its compatibility with planar fabrication techniques and applicability to a diversity of geometries and length scales. Its further development requires the capability of on-demand reversible shape reconfigurations, desirable for many emerging applications (e.g., responsive metamaterials, soft robotics). Here, the design, fabrication, and modeling of soft electrothermal actuators based on laser-induced graphene (LIG) are reported and their applications in mechanically guided 3D assembly and human-soft actuators interaction are explored. Over 20 complex 3D architectures are fabricated, including reconfigurable structures that can reshape among three distinct geometries. Also, the structures capable of maintaining 3D shapes at room temperature without the need for any actuation are realized by fabricating LIG actuators at an elevated temperature. Finite element analysis can quantitatively capture key aspects that govern electrothermally controlled shape transformations, thereby providing a reliable tool for rapid design optimization. Furthermore, their applications are explored in human-soft actuators interaction, including elastic metamaterials with human gesture-controlled bandgap behaviors and soft robotic fingers which can measure electrocardiogram from humans in an on-demand fashion. Other demonstrations include artificial muscles, which can lift masses that are about 110 times of their weights and biomimetic frog tongues which can prey insects.

Laser reprogramming magnetic anisotropy in soft composites for reconfigurable 3D shaping

“…MRSM with reprogrammable magnetic anisotropies have a wide spectrum of applications. First, they are compatible with the recently demonstrated responsive buckling assembly for fabrication of 3D architectures 35 – 37 . To fabricate them, passive 2D films are selectively bonded onto the responsive substrates.…”

Physical Sensors Based on Laser-Induced Graphene: A Review

“…Electrothermal actuation. Soft electrothermal actuators based on PDMS coated LIG have been reported by Ling et al [104] LIG served as a heater to introduce temperature differences via joule heating. The stress caused by the thermal expansion difference between PI and PDMS could deform 2D structures into 3D architectures via global and local bending.…”

Designing Mechanical Metamaterials with Kirigami‐Inspired, Hierarchical Constructions for Giant Positive and Negative Thermal Expansion

“…Recent studies demonstrate that mechanical metamaterials with optimized microstructure architectures can yield unconventional thermal expansion behaviors, such as near‐zero thermal expansion, [ 1–5 ] negative thermal expansion, [ 6–11 ] and thermally induced shear. [ 12 ] These mechanical metamaterials are of increasing interest, because of their potential for use in applications such as high‐precision space optical systems, [ 13,14 ] adaptive connecting components in satellites, [ 15,16 ] flexible MEMS that require excellent thermal stability, [ 17–24 ] battery electrodes with unique thermal expansion, [ 25–29 ] dental fillings, [ 30 ] thermally controlled shape‐changing structures, [ 12,31–48 ] etc. In response to these opportunities, diverse metamaterial designs have been reported, either for the purpose of maintaining the original shape during temperature changes, or for matching the thermal expansion properties of surrounding/supporting components.…”