Laser Programmable Patterning of RGO/GO Janus Paper for Multiresponsive Actuators

Abstract

ease of preparation. As a pioneer of this field, Gracias' group has proposed several impressive bilayer actuators. For instance, a thermoresponsive theragripper with photopatternable poly(propylene fumarate) (PPF)/poly(N-isopropylacrylamide-coacrylic acid) (pNIPAM-AAc) bilayer structure has been developed for drug delivery. [28] Besides, Yang and co-workers have successfully fabricated stimuliresponsive actuators including an intelligent spring, a smart gripper, and a new type of "microrobot" based on the singlewall carbon nanotube (SWCNT) and polyvinylidene fluoride (PVDF) bilayer structure. [29] Zhu and co-workers reported novel soft electrothermal bimorph actuators made of polyimide (PI) and silver nanowire (AgNW)/polydimethylsiloxane (PDMS), which could be used in selfwalkers and soft grippers. [30] Despite a rapid progress has been made in this field, continuous efforts have been devoted to exploring new functional materials for further promotion of their performance.Graphene oxide (GO) that features ultrafast water adsorption/desorption capability, tunable physical/chemical properties, and tractable solution processing property holds great promise for developing smart bimorph actuators. Significantly, there exist plenty of oxygen-containing groups (OCGs) on GO sheets, which make GO a very hydrophilic material. [31] Water molecules can be adsorbed by GO easily and transferred freely among the GO multilayers. In this case, GO is very promising for moisture-responsive actuators. Additionally, the OCGs on GO sheets can be selectively removed or modified through various chemical/physical strategies, which can endow the resultant materials with conductivity, light absorption property, and high electrothermal and photothermal conversion efficiency. [32] Therefore, bimorph actuators based on GO or its derivatives, for instance reduced GO (RGO), also enable light and electrical actuation. Recently, GO has emerged as a versatile material for actuator design. For example, Liu and coworkers prepared an electromechanical ring-shaped actuator by combining an RGO layer with a PDMS layer, in which the RGO layer serves as an electric-heated layer in the electrothermal actuator. [33] Tang et al. combined thermally expanding microspheres (TEMs) with RGO to fabricate an RGO-TEM-PDMS/ PDMS bilayer actuator. They realized remote construction of 3D structures upon light irradiation, and the photothermal effect Graphene oxide (GO) with tunable physical/chemical properties is a versatile material for smart bimorph actuators. Using GO or its derivatives (e.g., reduced GO, RGO) as an active material, actuators can be manipulated under various external stimuli including moisture, light, temperature, and electricity. However, most of these GO-based actuators respond to a solo stimulus, which limits its cutting-edge applications in soft robotics. Here, the programmable patterning of RGO/GO Janus paper using a threshold-controlled direct laser writing (DLW) technology is reported. By combining the RGO/GO Janus paper with a common thermal...

Electro-responsive actuators based on graphene

“…developed a tape/RGO/GO actuator-based smart curtain by the binary cooperative complementarity ( Figure 8 A). 126 As shown in Figure 8 B, the tape/RGO/GO actuators bend to the GO side under light and electricity stimuli because of a large CTE mismatch between the tape layer (≈137 ppm K −1 ) and the GO layer (0.85 ppm K −1 ). 146 Tape/RGO/GO actuators bend to the tape side under moisture stimuli because the tape is inert to moisture, and the GO layer expands by absorbing water molecules.…”

“… 50 Meanwhile, laser technologies are capable of high-efficiency, mask-free patterning, and hierarchical structuring of graphene, which is of benefit to the design and fabrication of electrothermal actuators. As typical examples, RGO- or LIG-based electrothermal actuators, including LRGO/PI, 122 Ag-LRGO/PI, 123 LRGO/polyethylene (LRGO/PE), 124 PI/LIG/PVDF, 125 GO/RGO/tape, 126 and PI/LIG/PDMS 39 structures have been successfully developed, demonstrating sophisticated deformation ability. The hierarchical structure of graphene plays an important role for the performances of ERAs.…”

The gorgeous transformation of paper: from cellulose paper to inorganic paper to 2D paper materials with multifunctional properties

“…12e and f). Based on the property of anisotropic water-molecule adsorption for smart actuators, there are also some reports that further explored the gradient reduction of graphene oxide to obtain anisotropic Janus GO/RGO paper, such as laser interference 260,261 or laser writing, 262 reductions triggered by different reduction and oxidation properties, 263 unilateral ultraviolet (UV) irradiation, 264 chemical reduction with hydriodic acid (HI) 265 and others. 266 Among them, compared with laser writing and sunlight irradiation, Han and co-workers 264 further found that UV is conducive to the large-scale, efficient, and simple production of bilayer GO/RGO paper with a more uniform structure, resulting in a stable response and performing complex actions after external stimuli.…”

Laser Fabrication of Bioinspired Gradient Surfaces for Wettability Applications

“…[81] Laser processing can produce various precise and detailed patterns, which has been widely applied to various samples with wide applications, such as surface-enhanced Raman scattering substrates, power generators, supercapacitors, sensors, and actuators. [82][83][84][85][86][87][88][89][90][91] Line-by-line scanning and point-by-point ablation can both be realized by adjusting the scanning speed. Line-by-line scanning is widely used to produce separate microgrooves or homogeneous large-area coarse surfaces.…”