Microfluidic Approaches for Microactuators: From Fabrication, Actuation, to Functionalization

Abstract

Microactuators can autonomously convert external energy into specific mechanical motions. With the feature sizes varying from the micrometer to millimeter scale, microactuators offer many operation and control possibilities for miniaturized devices. In recent years, advanced microfluidic techniques have revolutionized the fabrication, actuation, and functionalization of microactuators. Microfluidics can not only facilitate fabrication with continuously changing materials but also deliver various signals to stimulate the microactuators as desired, and consequently improve microfluidic chips with multiple functions. Herein, this cross‐field that systematically correlates microactuator properties and microfluidic functions is comprehensively reviewed. The fabrication strategies are classified into two types according to the flow state of the microfluids: stop‐flow and continuous‐flow prototyping. The working mechanism of microactuators in microfluidic chips is discussed in detail. Finally, the applications of microactuator‐enriched functional chips, which include tunable imaging devices, micromanipulation tools, micromotors, and microsensors, are summarized. The existing challenges and future perspectives are also discussed. It is believed that with the rapid progress of this cutting‐edge field, intelligent microsystems may realize high‐throughput manipulation, characterization, and analysis of tiny objects and find broad applications in various fields, such as tissue engineering, micro/nanorobotics, and analytical devices.

Innovations in spider silk‐inspired artificial gel fibers: Methods, properties, strengthening, functionality, and challenges

“…However, this endeavor poses considerable challenges due to the intricate nature of natural environment. 21 For large-scale manufacture of artificial spider silks, the spinning techniques are required to be scalable and compliant with industry benchmarks (e.g., electrospinning, 22 microfluidic, 23,24 wet-or dry spinning, 25,26 capillary polymerization, 27 dynamic interfacial spinning, 28 and 3D and 4D printing [29][30][31] ).…”

“…223 Resulting from the physicochemical properties and non-covalent interactions of substituent group, gel fibers possess abundant structures and excellent adjustability, making them excellent aspirants for an extensive series of advanced uses. 23,177,224 This section will highlight applications of gel fiber functional systems in different domains, encompassing fiber-shaped energy storage, sensors, biomedical materials, actuators, smart fabrics/textiles, artificial muscles, and biomimetic platforms. 92,[225][226][227][228][229][230]…”

Bioinspired Superwetting Open Microfluidics: From Concepts, Phenomena to Applications

“…In general, the development of bioinspired superwetting open microfluidics has moved from traditional directional transport, [35,37,101,109] water collection, [159] droplet manipulation [160] to more intelligent, microscopic, and comprehensive fields, such as microrobots, [18,[161][162][163][164] microsensors, micronano manufacturing biological inspection, smart fabric and so on. [165][166][167][168][169] This is an important time for researchers to pay more attention to this field and to strengthen the interaction with other areas. Therefore, it is important to emphasize that bioinspired superwetting open microfluidics needs to be extended to more niche open microfluidic devices, such as thread-based open microfluidic devices, [170][171][172] thin film vortex fluidic devices (VFD), [173][174][175] and so on.…”

Micro‐Acoustic Holograms for Detachable Microfluidic Devices

“…[8][9][10][11][12] Microfluidic devices offer unique advantages over conventional laboratory techniques due to their compact nature, low fabrication cost, rapid turnaround time, and precise microenvironment control. [13][14][15][16][17][18] Several approaches have been developed to actively achieve micromanipulation in microfluidic devices, including microgrippers, [19,20] electrowetting, [21][22][23] and magnetic [24][25][26] optical [27,28] and acoustic [29][30][31][32][33] forces. Among these methods, acoustic methods have been widely used due to their advantages in being contactless, biocompatible, and ability to achieve manipulation on cellular length scales.…”