3D Temporary‐Magnetized Soft Robotic Structures for Enhanced Energy Harvesting

Abstract

rigid devices, soft microsystems commonly adopt functional materials with appealing properties, such as dielectric elastomers, [10] shape-memory polymers, [11] liquid metals, [12] and hydrogels. [13] Reliable actuation is of vital importance in micro systems, especially for energy harvesting, where the mechanical stability, controllability, and adaptability are highly desired to maintain the long-term power output in a complex environment. Recent advances in materials have enabled soft actuators with different driving mechanisms, including magnetic effect, [14] chemical effect, [15] photo thermal effect, [16] and electrical effect. [17] The introduction of biomimetic designs or multidimensional geometries allows for the continuous operation in complex environments. [18][19][20][21][22] Among these strategies, the magnetic-controlled approach shows compelling advantages, due to its fast response, large deformation, precise control and stable repeatability. [23][24][25] Magnetic materials deform under external magnetic fields, which is crucial for magnetic-controlled structures. [26][27][28] Most magnetic-controlled robotics exploit magnetic materials to achieve various locomotion, where the permanent and programmed magnetization profiles are key design parameters. [29] Strong magnetic fields from these permanent magnets pose a variety of incompatibility issues in scenarios such as electronic circuit, biomedicine, and micro/nanomanufacturing. By contrast, magneticThe advent of functional materials offers tremendous potential in a broad variety of areas such as electronics, robotics, and energy devices. Magnetic materials are an attractive candidate that enable multifunctional devices with capabilities in both sensing and actuation. However, current magnetic devices, especially those with complex motion modalities, rely on permanently magnetized materials with complicated, non-uniform magnetization profiles. Here, based on magnetic materials with temporary-magnetization, a mechanically guided assembly process successfully converts laser-patterned 2D magnetic materials into judiciously engineered 3D structures, with dimensions and geometries ranging from mesoscale 3D filaments, to arrayed centimeter-scale 3D membranes. With tailorable mechanical properties and highly adjustable geometries, 3D soft structures can exhibit various tethered locomotions under the precise control of magnetic fields, including local deformation, unidirectional tilting, and omnidirectional rotation, and can serve as dynamic surfaces for further integration with other functional materials or devices. Examples demonstrated here focus on energy-harvesting systems, including 3D piezoelectric devices for noncontact conversion of mechanical energy and active motion sensing, as well as 3D solar tracking systems. The design strategy and resulting magnetic-controlled 3D soft structures hold great promise not only for enhanced energy harvesting, but also for multimodal sensing, robotic interfaces, and biomedical devices.

Flexible Electronics and Devices as Human–Machine Interfaces for Medical Robotics

“…[ 68,69 ] Notably, 3D flexible electronics maintain conductivity while gaining an extra dimension and thus more sophisticated functions that 2D electronics do not offer (Figure 3E,F). [ 70–72 ]…”

Metamaterial Absorbers: From Tunable Surface to Structural Transformation

“…Further research should explore smart materials and creative methods to transform complex shapes in micron scale, enabling the manipulation of THz MAs. For example, through mechanically or magnetically guided assembly approach, 2D magnetic patterns are programmable and can be converted into engineered 3D structures in a fast speed, [ 232,233 ] providing a promising alternative to realize tunable/reconfigurable MAs.…”

“…For example, through mechanically or magnetically guided assembly approach, 2D magnetic patterns are programmable and can be converted into engineered 3D structures in a) The Fermi energy (E f ) of graphene. a fast speed, [232,233] providing a promising alternative to realize tunable/reconfigurable MAs.…”

Multicomponent and multifunctional integrated miniature soft robots

“…In order to realize complex 3D structures, researchers have developed self-rolling and compressive buckling technology. 72,[105][106][107][108] By controlling the formation of internal stress, robotic structures integrated with electronic components could exhibit hierarchical 3D layouts. For example, Kim et al developed 3D microfliers loaded with electronic components (e.g., silicon nanofilm transistors and near-field communication (NFC) chips), as shown in Fig.…”