Four-Dimensional Printing of Stimuli-Responsive Hydrogel-Based Soft Robots

The present protocol describes the creation of four-dimensional (4D), time-dependent, shape-changeable, stimuli-responsive soft robots using a ...

Sookmyung Women's University

sookmyung women's university

A variety of biomimetic stimuli-responsive soft grippers that can be utilized as intelligent actuators, sensors, or biomedical tools have been developed. This review covers stimuli-responsive materials, fabrication methods, and applications of soft grippers. This review specifically describes the current research progress in stimuli-responsive grippers composed of N-isopropylacrylamide hydrogel, thermal and light-responding liquid crystalline and/or pneumatic-driven shape-morphing elastomers. Furthermore, this article provides a brief overview of high-throughput assembly methods, such as photolithography and direct printing approaches, to create stimuli-responsive soft grippers. This review primarily focuses on stimuli-responsive soft gripping robots that can be utilized as tethered/untethered multiscale smart soft actuators, manipulators, or biomedical devices.

Advances in biomimetic stimuli responsive soft grippers.

Stimuli-responsive hydrogels that exhibit reversible volume changes in response to stimulus cues such as heat, pH, and light have been utilized in soft robotics, microfluidics, electronics, and biomedical surgical tools. While the development of the soft robotics has widely expanded, most external triggering systems still have limited utilities due to the low selectivity. We present a hybrid gripper capable of undergoing preprogrammed shape transformation utilizing ultrasound energy on-off processes as the external triggering system, which can be utilized in invisible and nonselective environments. Furthermore, we describe the magnetic locomotion of the soft gripper enabled by the introduction of iron oxide (FeO) ferrogel. By integrating these dual ultrasonic and magnetic control systems, we demonstrate the soft gripper could actively and safely perform pick-and-place tasks on a biological salmon roe in the aqueous maze environment. We expect that this study can provide the groundwork for the further important advances to the creation of ultrasound-responsive shape programmable and multifunctional smart soft robots.

Untethered Actuation of Hybrid Hydrogel Gripper via Ultrasound.

Time-dependent shape-transferable soft robots are important for various intelligent applications in flexible electronics and bionics. Four-dimensional (4D) shape changes can offer versatile functional advantages during operations to soft robots that respond to external environmental stimuli, including heat, pH, light, electric, or pneumatic triggers. This review investigates the current advances in multiscale soft robots that can display 4D shape transformations. This review first focuses on material selection to demonstrate 4D origami-driven shape transformations. Second, this review investigates versatile fabrication strategies to form the 4D mechanical structures of soft robots. Third, this review surveys the folding, rolling, bending, and wrinkling mechanisms of soft robots during operation. Fourth, this review highlights the diverse applications of 4D origami-driven soft robots in actuators, sensors, and bionics. Finally, perspectives on future directions and challenges in the development of intelligent soft robots in real operational environments are discussed.

4D Multiscale Origami Soft Robots: A Review.

While graphene shows great potential for diverse device applications, to broaden the scope of graphene-based device applications further, it would be necessary to tune the electronic state of graphene and its resultant electrical properties properly. Surface decoration with metal nanoparticles is one of the efficient doping methods to control the properties of two-dimensional materials. Here, we report the p-type doping effects in single-layer graphene decorated with silver nanoparticles (AgNPs) that were formed area-selectively by the facile one-step photoreduction (PR) process based on focused-laser irradiation. During the PR process, AgNPs were reduced on graphene in AgNO solution by laser-driven photoexcitation followed by chemical reactions. Based on scanning electron microscopy analyses, the morphology characteristics of AgNPs were shown to be modulated by the laser dwell time and power controllably. Further, p-type doping effects were demonstrated using graphene-field-effect transistor structures whose graphene channels were selectively decorated with AgNPs by the PR process, as validated by the decrease in channel resistance and the shift of the Dirac point voltage. Moreover, the growth of AgNPs was observed to be more active on the graphene channel that was laser-annealed ahead of the PR process, leading to enhancing the efficiency of this approach for altering device characteristics.

Tailorable Electronic and Electric Properties of Graphene with Selective Decoration of Silver Nanoparticles by Laser-Assisted Photoreduction.

Biodegradable soft robots have been proposed for a variety of intelligent applications in soft robotics, flexible electronics, and bionics. Biodegradability offers an extraordinary functional advantage to soft robots for operations accompanying smart shape transformation in response to external stimuli such as heat, pH, and light. This review primarily surveyed the current advanced scientific and engineering strategies for integrating biodegradable materials within stimuli-responsive soft robots. It also focused on the fabrication methodologies of multiscale biodegradable soft robots, and highlighted the role of biodegradable soft robots in enhancing the multifunctional properties of drug delivery capsules, biopsy tools, smart actuators, and sensors. Lastly, the current challenges and perspectives on the future development of intelligent soft robots for operation in real environments were discussed.

ChangKyu Yoon

Department of Mechanical Systems Engineering,
Institute of Advanced Materials and Systems

Sookmyung Women's University

Four-Dimensional Printing of Stimuli-Responsive Hydrogel-Based Soft Robots

ChangKyu Yoon

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Department of Mechanical Systems Engineering,Institute of Advanced Materials and Systems

Sookmyung Women's University

Four-Dimensional Printing of Stimuli-Responsive Hydrogel-Based Soft Robots

Department of Mechanical Systems Engineering,
Institute of Advanced Materials and Systems