Untethered microgripper-the dexterous hand at microscale

Abstract

Untethered microgrippers that can navigate in hard-to-reach and unpredictable environments are significantly important for biomedical applications such as targeted drug delivery, micromanipulation, minimally invasive surgery and in vivo biopsy. Compared with the traditional tethered microgrippers, the wireless microgrippers, due to the exceptional characteristics such as miniaturized size, untethered actuation, dexterous and autonomous motion, are projected to be promising microtools in various future applications. In this review, we categorize the untethered microgrippers into five major classes, i.e. microgrippers responsive to thermal, microgrippers actuated by magnetic fields, microgrippers responsive to chemicals, light-driven microgrippers and hybrid actuated microgrippers. Firstly, the actuation mechanisms of these microgrippers are introduced. The challenges faced by these microgrippers are also covered in this part. With that, the fabrication methods of these microgrippers are summarized. Subsequently, the applications of microgrippers are presented. Additionally, we conduct a comparison among different actuation mechanisms to explore the advantages and potential challenges of various types of microgrippers. In the end of this review, conclusions and outlook of the development and potential applications of the microgrippers are discussed.

Hydrogel-Based Stimuli-Responsive Micromotors for Biomedicine

“…However, the obvious drawback of this micromotor with such a simple geometrical shape lies in its poor operability dimension and limited opening width and strength for gripping action. Hence, more advanced thermo-responsive micromotors, especially microgrippers [ 47 ], have been developed when researchers attempted to realize more degrees of freedom in object operation at the microscopic size. For example, after modifying the surface of stomatocyte-like micromotors with the PNIPAM polymer brushes, the opening of bioinspired micromotors can be enlarged or narrowed by the stimulation of temperature.…”

Engineering Biological Tissues from the Bottom-Up: Recent Advances and Future Prospects

“…In tissue manufacturing, microrobots can be used to assemble blood vessels (Figure 15B) [99]. In this process, the microrobot uses the pickup and placement function to thread the microgel module units onto the robotic arm and eventually form blood vessels [102]. The arm is divided into the double manipulator transition micromodule, double manipulator non-transition micromodule, and single manipulator up-and-down microassembly [100].…”

Self-Folding Non-Invasive Miniature Robots: Progress and Trend in the Biomedical Field

“…Similarly to the crease patterns, folds, and faces that constitute projects in the field of origami engineering, tetherless microgrippers consist of rigid segments separated by flexible hinges. Their miniaturized scale allows them to possess a higher range of motion and can be remotely triggered, with promising applications in confined spaces such as the cardiovascular system, though there is still considerable development needed before implemented in clinical applications [56].…”