Hydrogel microstructures that encapsulate cells can be assembled into tissues and have broad applications in biology and medicine. However, 3D posture control for a single arbitrary microstructure remains a challenge. A novel 3D manipulation and assembly technique based on optothermally generated bubble robots is proposed. The generation, rate of growth, and motion of a microbubble robot can be controlled by modulating the power of a laser focused on the interface between the substrate and a fluid. In addition to 2D operations, bubble robots are able to perform 3D manipulations. The 3D properties of hydrogel microstructures are adjusted arbitrarily, and convex and concave structures with different heights are designed. Furthermore, annular micromodules are assembled into 3D constructs, including tubular and concentric constructs. A variety of hydrogel microstructures of different sizes and shapes are operated and assembled in both 2D and 3D conformations by bubble robots. The manipulation and assembly methods are simple, rapid, versatile, and can be used for fabricating tissue constructs.
Soft
actuators that exhibit large deformation and can move at a
fast speed in response to external stimuli have been in high demand
for biomimetic applications. In this paper, we propose a convenient
approach to fabricate a reversible and thermal-responsive composite
hydrogel. Under the irradiation of visible light, the striped hydrogel
can bend at a speed of up to 65.72°/s with carbon nanotubes loaded
at a concentration of 3 mg/mL. A jellyfish-like miniature soft robot
is made using this hydrogel. When driven by visible light, the robot
can move at a maximum speed of 3.37 mm/s. Besides swimming, other
motion modes, including walking and jumping, are also achieved by
the robot. In addition, the robot can perform directional transportation
of tiny objects. As a new actuation approach for the research of jellyfish-like
miniature soft robots, this work is of great significance to the development
of flexible bionic robots. Moreover, this work also offers some important
insights into the research of biomimetic robots driven by visible
light.
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